LIVER TESTS AND DISEASES

• ACRONYMS

• AASLD - American Association for the Study of Liver Diseases
• AAT - Alpha-1 antitrypsin
• ACG - American College of Gastroenterology
• AIH - Autoimmune hepatitis
• ALP - Alkaline phosphatase
• ALT - Alanine aminotransferase
• AMA - Antimitochondrial antibodies
• ANA - Antinuclear antibodies
• ASMA - Anti-smooth-muscle antibodies
• AST - Aspartate aminotransferase
• BMI - Body mass index
• EBV - Epstein-Barr virus
• ERCP - Endoscopic retrograde cholangio-pancreatography
• GGT - Gamma-glutamyl transferase
• HBV - Hepatitis B virus
• HCC - Hepatocellular carcinoma
• HCV - Hepatitis C virus
• HH - Hereditary hemochromatosis
• MRCP - MRI/magnetic resonance cholangiopancreatography
• NAFLD - Nonalcoholic fatty liver disease
• NASH - Non-alcoholic steatohepatitis
• PBC - Primary biliary cholangitis
• PSC - Primary sclerosing cholangitis
• ULN - Upper limit of normal
• USPSTF - U.S. Preventive Services Task force

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• ALANINE AMINOTRANSFERASE (ALT)

• Names
• Alanine aminotransferase (ALT)
• Serum glutamic pyruvic transaminase (SGPT)


• Physiology
• ALT is an enzyme that breaks down amino acids for use as energy. Its activity in the liver is 3000-fold higher than in other organs, so serum elevations are almost always caused by hepatocyte damage. Unlike AST, which is found in multiple organs (e.g. liver, heart, muscle, kidneys, brain), ALT is primarily a liver enzyme, making it a specific marker for hepatotoxicity. AST elevations with normal ALT levels suggest cardiac or muscle disease as opposed to liver disease.
• ALT levels are directly proportional to BMI, and studies that have excluded subjects with liver disease and/or a BMI > 25 have found the ALT upper limits of normal in men and women are 33 IU/L and 25 IU/L, respectively. The ACG endorses these conservative cutoffs, although they acknowledge that they would likely lead to much unnecessary testing and increased costs. [1,2]
• See ALT/AST elevations below for recommendations on evaluating high ALT levels

• Reference [1]

Normal ALT ranges
Sex	ALT value (U/L)
Male	29 - 33
Female	19 - 25

• Other factors affecting ALT levels
• Normal variation - day-to-day variations can be 10 - 30% in some people
• Body weight - ALT levels are directly proportional to body weight
• Regular exercise - ALT levels are 20% lower in people who exercise regularly compared to people who do not exercise
• Strenuous exercise - very strenuous exercise can cause acute elevations
• Hemolysis - hemolysis can cause a modest increase in ALT
• Muscle injury - muscle injury can cause a moderate increase in ALT [11]

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• ASPARTATE AMINOTRANSFERASE (AST)

• Names
• Aspartate aminotransferase (AST)
• Serum glutamic oxaloacetic transaminase (SGOT)


• Physiology
• AST is an enzyme that breaks down amino acids for use as energy. AST is found primarily in the liver and cardiac muscle and, to a lesser degree, in skeletal muscle, the kidneys, red blood cells, and the brain. AST activity is highest in the liver, and elevated levels are typically caused by liver damage; however, ALT, which is predominantly a liver enzyme, is more specific for hepatotoxicity. [1,2]
• See ALT/AST elevations below for recommendations on evaluating an elevated AST

• Reference [3]

Normal AST ranges
Sex	AST value (U/L)
Male	9 - 50
Female	9 - 40

• Other factors affecting AST levels
• Daily variation - day-to-day variation can be 5 - 10% in some people
• Race - values run 15% higher in African-American men
• Body weight - AST levels are directly proportional to body weight
• Strenuous exercise - strenuous exercise can cause a three-fold increase
• Hemolysis - hemolysis can cause a significant increase in AST
• Muscle injury - muscle injury causes a significant increase in AST levels [11]

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• ALKALINE PHOSPHATASE (ALP)

• Physiology
• Alkaline phosphatase (ALP) is an enzyme that catalyzes the hydrolysis of phosphate esters at an alkaline pH. ALP is present in the liver, bone, intestine, kidneys, and placenta. Under normal conditions, 80% of circulating ALP originates from the liver and bones.
• In the liver, ALP is present in the canalicular membrane of hepatocytes that line tubules where bile is formed. Bile duct obstruction increases ALP synthesis, causing serum levels to rise; even minor obstructions that do not affect bilirubin levels will increase ALP. Another canalicular enzyme, GGT, rises with ALP and can be used to determine if ALP elevations are hepatic (elevated GGT) or nonhepatic (normal GGT). Each source of ALP produces a unique isoenzyme that can be identified with blood testing so that the origins of circulating ALP can be determined. [1,3]
• See ALP elevations below for recommendations on evaluating an elevated ALP

• Reference [3]

Normal ALP ranges
Age (years)	Male (U/L)	Female (U/L)
13 - 14	126 - 499	90 - 306
30 - 35	40 - 112	40 - 114
52 - 55	40 - 120	40 - 133
≥ 66	40 - 125	40 - 142

• Other factors affecting ALP levels
• Fatty meal and blood type - intestinal ALP activity is higher in patients with blood types O and B, and fatty meals can make levels rise
• Pregnancy - placental ALP synthesis increases levels
• Elderly - ALP levels rise with age, especially in women
• Conditions associated with increased bone remodeling
• Postmenopausal women
• Childhood
• Healing fractures
• Hyperthyroidism
• Hyperparathyroidism
• Osteoporosis treatment
• Paget's disease
• Osteomalacia
• Bone metastasis [1,3]

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• GAMMA-GLUTAMYL TRANSPEPTIDASE (GGT)

• Physiology
• Gamma-glutamyl transpeptidase (GGT) is an enzyme that assists in the transfer of amino acids across membranes. GGT is present with ALP in the canalicular membrane of hepatocytes that line tubules where bile is formed. GGT is also found in the kidneys, seminal vesicles, pancreas, spleen, heart, and brain. In cases where ALP is elevated, but other liver tests are normal, GGT can help determine if the ALP elevation is hepatic (elevated GTT) or nonhepatic (normal GTT).
• GGT levels are often very high in alcoholic liver disease and are sometimes used to detect and monitor alcohol intake; however, they are not specific for alcohol abuse
• A number of nonhepatic conditions (see below) can raise GGT levels, so they are not routinely used to screen for liver disease [1,3]

• Reference [3]

Normal GGT range
Sex	GGT value (U/L)
Male	< 60
Female	< 40

• Other conditions affecting GGT levels
• Pancreatic disease
• Myocardial infarction
• Renal failure
• Systemic lupus erythematosus
• Emphysema
• Diabetes
• Medications - carbamazepine, cimetidine, furosemide, heparin, isotretinoin, methotrexate, oral contraceptives, phenobarbital, phenytoin, and valproic acid
• Increased body weight

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• BILIRUBIN

• Physiology
• Bilirubin is a byproduct of hemoglobin metabolism. When dying RBCs release hemoglobin, macrophages consume it and break it down into iron and bilirubin, which is released back into the bloodstream, removed by the liver, and secreted into the bile. See red blood cell life cycle for more.
• In the blood, most bilirubin circulates in the unconjugated form, tightly bound to albumin. In the liver, bilirubin is conjugated by uridine 5’-diphospho (UDP)-glucuronosyltransferase, making it water soluble so that it can be excreted into the bile. Conjugated bilirubin is referred to as "direct bilirubin," and unconjugated bilirubin is called "indirect bilirubin."
• Total bilirubin levels are typically less than 1.1 mg/dl, with about 70% unconjugated and the remaining conjugated. Increases in total bilirubin from conjugated (direct) bilirubin are a sign of hepatocellular dysfunction and/or a decrease in bile flow (cholestasis). Elevations in unconjugated bilirubin can occur with hemolysis (see hemolytic anemia), decreased hepatic uptake, and/or decreased hepatic conjugation (see Gilbert's syndrome below).
• See bilirubin elevations below for recommendations on evaluating an elevated bilirubin

• Normal bilirubin in adults
• less than 1.2 mg/dl [3]

• Other factors affecting bilirubin levels
• Fasting (≥ 36 hours)
• Conditions that increase hepatic congestion (e.g. CHF, COPD, pulmonary embolism, cor pulmonale)
• Malnutrition
• Medications (see below)

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• ALBUMIN

• Physiology
• Albumin, which is synthesized in the liver and released into the bloodstream, is the primary circulating protein, accounting for 55 - 65% of total plasma protein. It has two primary functions: (1) binding compounds with low water solubility (e.g. free fatty acids, hormones, calcium, zinc, certain medications) so that they can be transported in the blood; (2) maintaining intravascular oncotic pressure.
• A reduction in albumin levels (≤ 3.5 g/dl) can be a sign of liver disease, although it is not specific for it (see below). Albumin has a half-life of 3 weeks, so liver disease must be present for longer than 3 weeks for levels to fall.

• Normal albumin in adults
• 3.5 - 5.2 g/dl [3]

• Factors that lower albumin levels
• Decreased synthesis
• Liver disease
• Malnutrition
• Malabsorption (e.g. inflammatory bowel disease, celiac disease)
• Inflammation
• Increased breakdown
• Sepsis
• Increased loss
• Nephrotic syndrome
• Burns
• Protein-losing enteropathy
• Fluid redistribution
• Edema
• Ascites
• Plasma expansion
• Intravenous fluids
• Pregnancy

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• CLOTTING STUDIES

• The liver produces most of the clotting factors involved in the coagulation cascade (see coagulation cascade). Significant liver disease can reduce factor production and prolong the prothrombin time (PT) and partial thromboplastin time (PTT). The PT is particularly sensitive to liver damage and can become elevated in less than 24 hours in cases of severe disease; the PTT involves more factors and does not rise as acutely. Cholestasis inhibits vitamin K absorption, reducing the production of vitamin K-dependent factors II, VII, IX, and X.
• When measuring liver function, the ACG recommends checking albumin and the PT [1,3]

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• LIVER TEST PATTERNS

• ALT to ALP ratio
• A measure called the R factor that uses the ratio of ALT to ALP to predict the origin of liver damage has been proposed. Its calculation and interpretation are described below.
• R ratio
• Calculation
• R factor = (ALT value/ALT ULN) / (ALP value/ALP ULN) [Online calculator]
• Findings
• R factor > 5: Hepatocellular injury
• R factor < 2: Cholestatic injury
• R factor 2 - 5: Mixed injury [1]

• ALT to AST ratio
• The ratio of ALT to AST can sometimes help identify the source of hepatotoxicity, although it is not highly specific for any condition. Typical ratios seen in many diseases are provided below.


• ALT > AST
• NAFLD and NASH
• Viral hepatitis
• Hepatotoxic medications
• Toxic hepatitis (amanita exposure)
• Hemochromatosis
• Autoimmune hepatitis
• Wilson’s disease
• Alpha-1-antitrypsin deficiency
• Celiac disease
• Acute bile duct obstruction
• Liver trauma
• Post-liver surgery
• Veno-occlusive disease/sinusoidal obstruction syndrome
• Diffuse infiltration of the liver with cancer
• HELLP syndrome
• Acute fatty liver of pregnancy
• Sepsis
• Hemophagocytic lymphohistiocytosis


• AST > ALT
• Alcoholic liver disease
• Cirrhosis (of any etiology)
• Ischemic hepatitis
• Congestive hepatopathy
• Acute Budd-Chiari syndrome
• Hepatic artery damage/thrombosis/occlusion
• TPN [1]

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• ELEVATED ALT/AST

• Overview
• ALT and AST elevations are common findings on laboratories. Both enzymes are directly proportional to BMI, and as the population has become more obese, the prevalence of high levels has increased, causing some experts to recommend BMI-adjusted normal ranges.
• Recommendations from the ACG for evaluating abnormal liver tests are presented below. The extent of the workup should be individualized, especially in overweight individuals with mild elevations, as up to one-third of Americans have fatty liver disease, which can only be treated with weight loss.

ACG 2017 Recommendations for Evaluating Elevated ALT / AST
Borderline / Mild Elevations (<5 X ULN)
Step 1 - assess patient Assess for hepatotoxic prescription medications, OTC medications, supplements, and alcohol use (see the NIH Livertox Database for hepatotoxicity information on a large number of medications and supplements) Assess risk factors for fatty liver (obesity, diabetes, dyslipidemia, hypertension) Assess risk factors for viral hepatitis Hepatitis C risk factors Hepatitis B risk factors In patients without overt signs of liver disease: If a hepatotoxic drug or supplement is identified, consider discontinuing the drug/supplement and rechecking enzymes in 6 weeks If patient consumes regular alcohol, recommend alcohol cessation and recheck enzymes in 6 weeks If patient is overweight, recommend weight loss and recheck at later date, keeping in mind that significant weight loss is difficult for most people to achieve
Step 2 - initial workup CBC with platelets Liver testing including ALP, bilirubin, and albumin PT/INR Hepatitis panel (should include HBsAg, HBcAb, HBsAb, HCV Ab) Iron studies - see hemochromatosis Abdominal ultrasound Negative findings If above workup does not reveal a source, consider observation for 3 - 6 months and then repeat liver tests If repeat testing is still elevated or concern for less common etiologies is high, proceed to next step
Step 3 - extended workup ANA, ASMA, IgG levels - see autoimmune hepatitis Ceruloplasmin - see Wilson disease Alpha-1 antitrypsin phenotype - see alpha-1 antitrypsin deficiency Other labs to consider based on individual history Celiac disease testing - see celiac labs Thyroid testing Muscle disorders Tick-borne diseases - Lyme disease, babesiosis, and ehrlichiosis Negative findings If no etiology is found, final step is liver biopsy
Moderate-to-Severe Elevation (≥ 5 X ULN)
History and physical Patients with moderate to severe elevations require immediate assessment Assess for hepatotoxic prescription medications, OTC medications, supplements, and alcohol use and discontinue all (see the NIH Livertox Database for hepatotoxicity information on a large number of medications and supplements) Assess for signs and symptoms of acute liver failure (e.g. jaundice, ascites, hepatomegaly, right upper quadrant pain, nausea and vomiting, mental status changes) Testing (all patients) CBC with platelets Liver testing including ALP, bilirubin, and albumin PT/INR Viral hepatitis testing (should include HAV IgM, HAV IgG, HBsAg, HBcAb IgM, HBcAb IgG, HBsAb, HCV Ab) Iron studies - see hemochromatosis ANA, ASMA, IgG levels - see autoimmune hepatitis Ceruloplasmin - see Wilson disease Abdominal ultrasound Extended testing for ALT > 15 X ULN Herpes simplex virus (HSV) Cytomegalovirus testing (CMV) Epstein–Barr virus (EBV) CK (to look for rhabdomyolysis) Anti-liver kidney microsomal antibody (LKM antibody) - see autoimmune hepatitis Serum and urine drug panel Consider n-acetyl cysteine level if any evidence of acetaminophen ingestion If there are signs of acute liver failure Urgent hepatology consult and consider referral to liver transplant center Negative testing If testing is negative, proceed to liver biopsy if stable

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• ELEVATED ALKALINE PHOSPHATASE (ALP)

• Overview
• Mild elevations of ALP are common and nonspecific for liver toxicity, as ALP may be elevated in other conditions (see alkaline phosphatase). Recommendations for evaluating high ALP levels are divided into isolated elevations, i.e., normal ALT, AST, bilirubin, and those that occur with other liver enzyme abnormalities (high AST, ALT, +/- bilirubin).

ACG 2017 Recommendations for Evaluating Elevated Alkaline Phosphatase (ALK)
Isolated elevated ALP (normal ALT, AST, and bilirubin)
Step 1 - check a GGT If GGT is normal Evaluate for nonhepatic causes of elevated ALP (see nonhepatic causes below) If GGT is elevated, perform the following: Abdominal ultrasound Evaluate for medications that can raise ALP (see medications below) AMA, ANA, ASMA - see primary biliary cholangitis
Step 2 - further evaluation based on results from above Evaluation negative and ALP > 2 X ULN Consider liver biopsy Evaluation negative and ALP 1 - 2 X ULN Consider observation for 6 months. If still elevated after 6 months, consider liver biopsy. If ductal dilation is present Perform ERCP or MRCP - see primary sclerosing cholangitis If AMA is positive Evaluate for primary biliary cholangitis
Elevated ALP with Elevated ALT/AST +/- Bilirubin
Step 1 - order abdominal ultrasound If ductal dilation is present Perform ERCP or MRCP - see primary sclerosing cholangitis If no ductal dilation is present Check AMA, ANA, ASMA - see primary biliary cholangitis
Step 2 - extended testing based on above results If AMA positive Evaluate for primary biliary cholangitis If AMA negative and ALP > 2 X ULN Consider liver biopsy or MRCP If AMA negative and ALP 1 - 2 X ULN Consider observation for 6 months. If still elevated after 6 months, consider liver biopsy or MRCP.

• Nonhepatic causes of ALP elevations
• Fatty meal and blood type - intestinal ALP activity is higher in patients with blood types O and B, and fatty meals can make levels rise
• Pregnancy - placental ALP synthesis increases levels
• Medications - see medications below
• Elderly - ALP levels rise with age, especially in women
• Conditions associated with an increase in bone remodeling
• Postmenopausal women
• Childhood
• Healing fractures
• Hyperthyroidism
• Hyperparathyroidism
• Osteoporosis treatment
• Paget's disease
• Osteomalacia
• Bone metastasis
• Other
• Chronic renal failure
• Lymphoma
• Extra-hepatic malignancy
• Congestive heart failure
• Infection
• Inflammation
• Myeloid metaplasia
• Peritonitis
• Diabetes mellitus
• Gastric ulcer [1,3]

• Medications associated with ALP increases
• NOTE: See the NIH Livertox Database for hepatotoxicity information on a large number of medications and supplements
• Amitriptyline
• Amoxicillin/clavulanate
• Anabolic steroids
• Azathioprine
• Captopril
• Carbamazepine
• Chlorpromazine
• Clindamycin
• Clopidogrel
• Cyproheptadine
• Enalapril
• Erythromycins
• Estrogens
• Irbesartan
• Minoxidil
• Mirtazapine
• Nitrofurantoin
• Oral contraceptives
• Phenobarbital
• Phenothiazines
• Phenytoin
• Sulfonamides
• Terbinafine
• Topiramate
• Trazodone
• Tricyclic antidepressants
• Trimethoprim/sulfamethoxazole
• Verapamil
• Zonisamide [4,5]

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• ELEVATED BILIRUBIN

• Overview
• The first step in evaluating elevated total bilirubin is to determine if the increase is in unconjugated (indirect) or conjugated (direct) bilirubin. Increases in unconjugated bilirubin may occur from hemolysis, decreased hepatic uptake, or decreased hepatic conjugation, with Gilbert's syndrome being the most common etiology. Conjugated bilirubin elevations are typically secondary to parenchymal liver damage or biliary obstruction.

ACG 2017 Recommendations for Evaluating Elevated Bilirubin
Elevated Unconjugated (indirect) Bilirubin
Step 1 - initial testing and assessment Evaluate other liver tests (ALT, AST, ALP) Evaluate for medications that increase bilirubin (see medications below) Evaluate for Gilbert's syndrome Check for hemolysis (see hemolytic anemia)
Step 2 - further evaluation if above is negative Consider genotype testing (UGT1A1 genotype) for Gilbert's syndrome Look for other, less common causes (see other causes below) If no cause is found and elevations persist and/or AST/ALT elevations are present Consider liver biopsy
Elevated Conjugated (direct) Bilirubin
Step 1 - initial testing and assessment Evaluate other liver tests (ALT, AST, ALP) Evaluate for medications that can increase bilirubin (see medications below) Look for clinically overt etiologies: sepsis, TPN, cirrhosis, and biliary obstruction Perform abdominal ultrasound
Step 2 - further evaluation based on results from above If ductal dilation is present ERCP or MRCP - see primary sclerosing cholangitis If no ductal dilation is present Check AMA, ANA, ASMA - see primary biliary cholangitis If no cause is found and elevations persist and/or AST/ALT elevations are present Consider liver biopsy

• Causes of elevated bilirubin
• Unconjugated bilirubin elevations
• Gilbert’s syndrome (most common)
• Crigler-Najjar syndrome - rare congenital condition caused by UGT1A1 gene mutations that reduce bilirubin-UGT activity
• Hemolysis (intravascular and extravascular)
• Ineffective erythropoiesis
• Resorption of large hematomas
• Neonatal jaundice
• Hyperthyroidism
• Medications
• Post-blood transfusion
• Conjugated bilirubin elevations
• Bile duct obstruction
• Choledocholithiasis
• Malignant obstruction
• Bile duct fl ukes
• Bile duct stricture
• AIDS cholangiopathy
• Viral hepatitis
• Toxic hepatitis
• Medications or drug-induced liver injury
• Acute alcoholic hepatitis
• Ischemic hepatitis
• Cirrhosis
• Primary biliary cirrhosis
• Primary sclerosing cholangitis
• Infiltrative diseases of the liver
• Sarcoidosis
• Granulomatous hepatitis
• Tuberculosis
• Metastatic cancer
• Lymphoma
• Hepatocellular carcinoma
• Wilson disease (especially fulminant Wilson disease)
• Autoimmune hepatitis
• Ischemic hepatitis
• Congestive hepatopathy
• Sepsis
• Total parenteral nutrition
• Intrahepatic cholestasis of pregnancy
• Benign postoperative jaundice
• ICU or multifactorial jaundice
• Benign recurrent cholestasis
• Vanishing bile duct syndrome
• Ductopenia
• Dubin-Johnson syndrome - rare condition caused by genetic mutations in the transport protein involved in moving bilirubin from liver cells into the bile
• Rotor syndrome - rare condition caused by genetic mutations in OATP1B1/B3 transport proteins involved in transporting bilirubin from the blood into the liver
• Sickle cell liver crisis
• Hemophagocytic lymphohistiocytosis [1]

• Medications that have been associated with elevated bilirubin levels
• NOTE: See the NIH Livertox Database for hepatotoxicity information on a large number of medications and supplements
• Amoxicillin/clavulanate
• Anabolic steroids
• Canagliflozin (Invokana®)
• Chlorpromazine
• Clopidogrel
• Oral contraceptives
• Erythromycins
• Estrogens
• Febuxostat (Uloric®)
• Glecaprevir (Mavyret®)
• Irbesartan
• Mirtazapine
• OATP1B1/B3 inhibitors - bilirubin is transported by OATP1B1/B3 from blood into hepatocytes, and OATP1B1/B3 inhibitors may block its transport, raising levels
• Paritaprevir (Viekira Pak®)
• Pibrentasvir (Mavyret®)
• Phenothiazines
• Ribavirin - causes hemolytic anemia
• Siponimod (Mayzent®)
• Terbinafine
• Tocilizumab (Actemra®)
• Tricyclic antidepressants
• Voxilaprevir (Vosevi®) [4,5]

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• GILBERT'S SYNDROME

• Pathology
• Gilbert's syndrome is a benign condition that causes mild elevations in unconjugated (indirect) bilirubin. In the liver, bilirubin is conjugated by uridine 5’-diphospho (UDP)-glucuronosyltransferase, making it water soluble so that it may be excreted into the bile. In Gilbert's syndrome, genetic defects in UDP-glucuronosyltransferase reduce its ability to conjugate bilirubin efficiently. [1]


• Epidemiology
• Gilbert's syndrome is present in 3 - 7% of the U.S. population, making it the most common cause of elevated unconjugated bilirubin


• Diagnosis
• Gilbert's syndrome presents as isolated elevations of unconjugated bilirubin, with total bilirubin levels that rarely exceed 6 mg/dl and are usually < 3 mg/dl
• Hemolysis is another cause of elevated unconjugated bilirubin and should be ruled out before making a diagnosis of Gilbert's syndrome
• Genetic testing is available to aid in the diagnosis (UGT1A1 genotyping) but is rarely necessary
• In general, Gilbert's syndrome can be assumed in healthy patients who meet the following criteria:
• Indirect hyperbilirubinemia < 4 mg/dl
• Normal ALT, AST, and ALP
• No signs of hemolysis (normal reticulocyte count and/or LDH/haptoglobin). See labs to detect hemolysis for more.
• Not taking medications that elevate bilirubin (see meds that elevate bilirubin) [1]


• Treatment
• Gilbert's syndrome is a benign condition that does not require treatment

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• NONALCOHOLIC FATTY LIVER DISEASE

• Definitions
• Nonalcoholic fatty liver disease (NAFLD) - NAFLD encompasses all of the liver diseases associated with fatty infiltration of the liver in patients without significant alcohol consumption, long-term use of a steatogenic medication, or monogenic hereditary disorders
• Nonalcoholic fatty liver (NAFL) - NAFL is defined as ≥ 5% hepatic steatosis without evidence of hepatocellular injury in the form of hepatocyte ballooning or fibrosis. The risk of progression to cirrhosis and liver failure is considered minimal.
• Nonalcoholic steatohepatitis (NASH) - NASH is defined as ≥ 5% hepatic steatosis with inflammation and hepatocyte injury (ballooning) with or without fibrosis. NASH can progress to cirrhosis, liver failure, and, in rare cases, liver cancer.

• Prevalence
• Worldwide, the estimated prevalence of NAFLD is around 25%, with the Middle East and South America having the highest rates at > 30% and Africa the lowest at 13%. In the U.S., the prevalence is estimated to be between 20 - 30%. Men are affected more than women, and Hispanics have the highest rates, while blacks have the lowest.
• Among patients with NAFLD, about 20% are estimated to have NASH, which equates to 3 - 6% of the general population

• Risk factors
• Most risk factors for NAFLD are also associated with obesity, making causality difficult to establish. The table below lists the most common risk factors for NAFLD.

• Reference [1,2,8]

Risk factors for NAFLD
Obesity 80% of NAFLD patients are overweight or obese Any degree of excess weight increases NAFLD risk
Type 2 diabetes NAFLD is present in up to 66% of diabetics
Dyslipidemia Dyslipidemia is present in 72% of NAFLD patients, particularly high triglycerides and low HDL
Metabolic syndrome More than 40% of NAFLD patients meet the definition of metabolic syndrome Metabolic syndrome is defined as ≥ 3 of the following: Waist circumference > 102 cm (men) | > 88 cm (women) Triglycerides ≥ 150 mg/dl HDL < 40 mg/dl (men) | < 50 mg/dl (women) SBP ≥ 130 mmHg or DBP ≥ 85 mmHg Fasting blood sugar ≥ 110 mg/dl
Polycystic ovary disease (PCOS) Women with PCOS have a higher prevalence of NAFLD
Male sex Men are affected twice as much as women
Race Hispanics are affected more than other races, and Blacks have the lowest prevalence

• Pathology
• NAFLD develops through the following steps:
• Adipose tissue accumulates in hepatocytes secondary to obesity, dyslipidemia, and other factors
• Accumulating adipose tissue inflicts oxidative and metabolic stress on the hepatocyte, causing it to expand in size (ballooning)
• Eventually, the stressors become too much, and the hepatocyte dies, releasing inflammatory mediators that stimulate vascular remodeling, fibrogenesis, and the accumulation of immature liver epithelial cells [8]

• Natural course
• NAFLD progresses in the following order: NAFL → NASH → Cirrhosis → Hepatocellular carcinoma
• 25% of patients with NAFL will develop NASH
• 25% of patients with NASH will develop cirrhosis (about 6.25% of patients with NAFL)
• Hepatocellular carcinoma has an annual incidence of 1 - 2% among patients with NASH-related cirrhosis [8]

• Diagnosis
• Hepatic steatosis is easily detected on a number of imaging studies, including ultrasound, CT scan, and MRI. The diagnostic challenge lies in determining which patients should have further testing for NASH. Several risk prediction tools and specialized tests have been developed to detect fibrosis. AASLD recommendations for evaluating patients at risk for NASH are provided below, along with a review of available diagnostic modalities.

• Reference [37]

2023 AASLD recommendations for diagnosing NASH
Step 1 Screen at-risk patients with the FIB-4 score FIB-4 < 1.3 Reassess periodically. Every 1 - 2 years in diabetics and people with metabolic risk factors; every 2 - 3 years in everyone else FIB-4 of 1.3 - 2.67 Proceed to Step 2 FIB-4 > 2.67 Consider GI/Hepatology referral or proceed to Step 2
Step 2 Perform VCTE (Fibroscan) or enhanced liver fibrosis (ELF) test Low-risk (VCTE < 8.0 or ELF < 7.7) No further workup. Reassess periodically. Intermediate-risk (VCTE 8 - 12 or ELF 7.7 - 9.8) Refer to GI/Hepatology High-risk (VCTE > 12 or ELF > 9.8) Refer to GI/Hepatology

• Liver ultrasound
• Liver ultrasound, the most common test for evaluating liver enzyme elevations, has good sensitivity for identifying hepatic steatosis but limited ability to detect NASH. In a study where MRI-PDFF was used as a reference stadard, ultrasound had a sensitivity and specificity of 89% and 81%, respectively, for detecting any degree of steatosis and 83% and 81% for mild steatosis. [35]

• Magnetic resonance imaging proton density fat fraction (MRI-PDFF)
• MRI-PDFF is a new MRI technique that provides a quantitative assessment of hepatic steotosis. It is highly sensitive for even mild steatosis and can be used to monitor disease progression. Currently, it is primarily used in clinical trials and is not widely available. [37]

• Fibrosis 4 score (FIB-4)
• The FIB-4 is a risk calculator that estimates the presence of NASH based on a patient's age, platelet count, ALT, and AST
• An online calculator is available here - Fibrosis 4 score calculator
• A score less than 1.45 makes NASH very unlikely, whereas a score greater than 3.25 indicates advanced fibrosis
• The AASLD guidelines recommend FIB-4 as a screening tool for patients at risk for NASH

• Enhanced liver fibrosis (ELF) test
• The enhanced liver fibrosis (ELD) test is a blood test that measures levels of three direct markers of liver fibrosis: hyaluronic acid, tissue inhibitor of metalloproteinase-1, and type III procollagen peptide. Results are placed in an algorithm that calculates a score predictive of the likelihood of progression to cirrhosis and liver-related clinical events within 3.9 years. [37,38]

• Vibration-controlled transient elastography (Fibroscan)
• Vibration-controlled transient elastography (VCTE), also referred to as Fibroscan, is a specialized ultrasound machine that uses a transducer to measure the velocity of a sound wave passing through the liver. The velocity is then used to calculate liver stiffness, a marker of fibrosis.
• VCTE scores are expressed as kilopascals (kPa), which are SI units of pressure. Scores less than 8.2 kPa make Metavir F2 or higher unlikely (97% negative predictive value), while scores greater than 12.1 kPa are indicative of clinically significant fibrosis.
• VCTE has a sensitivity of 85% for detecting advanced fibrosis and 92% for detecting cirrhosis [6,7,8,32]

• Liver biopsy
• Liver biopsy is the gold standard for diagnosing NASH, however, it is invasive and expensive, making other methods preferred. Criticisms of liver biopsy include interobserver variability and false negatives if the biopsy misses diseased tissue. [6,7,8,32]

• NAFLD fibrosis score
• The NAFLD fibrosis score predicts the presence of NASH based on patient's age, BMI, hyperglycemia, platelet count, albumin, and AST/ALT ratio.
• An online calculator is available here - NAFLD fibrosis score calculator
• In a meta-analysis that included 3,064 patients, a score of less than -1.455 had 90% sensitivity and 60% specificity to exclude advanced fibrosis, whereas a score greater than 0.676 had 67% sensitivity and 97% specificity to identify the presence of advanced fibrosis [6,7,8,32]

• Magnetic resonance elastography (MRE)
• MRE is a special MRI that uses sound waves to quantify liver stiffness, a marker of fibrosis. Like VCTE, findings are expressed in SI units or pressure (kilopascals, kPa), but the scales are different. A meta-analysis found that MRE values of <5 kPa, 5 - 8 kPa, and >8 kPa were associated with a risk of liver decompensation over 3 years of 1.6%, 17%, and 19%, respectively. MRE is expensive and not widely available. [37]

• AASLD 2023 NASH treatment recommendations
• Weight loss and exercise
• NASH treatment is primarily weight loss and exercise, which has a positive effect independent of weight reduction
• Overweight patients should lose weight, and all patients should exercise. Weight-loss medications and bariatric surgery should be considered in patients who struggle to achieve significant weight reduction.
• Medications
• No medication has received FDA approval to treat NASH, although some have shown a benefit in trials
• Semaglutide can be considered for its approved indications (T2DM/obesity) in patients with NASH, as it confers a cardiovascular benefit and improves NASH
• Pioglitazone improves NASH and can be considered for patients with NASH in the context of patients with T2DM
• Vitamin E can be considered in select individuals as it improves NASH in some patients without diabetes
• Available data on semaglutide, pioglitazone, and vitamin E do not demonstrate an antifibrotic benefit, and none has been carefully studied in patients with cirrhosis
• Metformin, ursodeoxycholic acid, dipeptidyl peptidase-4, statins, and silymarin are well studied in NASH and should not be used as a treatment for NASH as they do not offer a meaningful histological benefit [37]

• Weight loss
• The primary treatment for NAFLD is weight loss, and its effects can be profound. Results from a study where 293 patients with biopsy-proven NASH were instructed on how to lose weight and followed for a year are presented in the table below. Liver biopsies were performed at the beginning and end of the study on all patients.

• Exercise
• Exercise has been shown to improve NAFLD independent of weight loss. Vigorous exercise appears to have the greatest effect. [6,7]

• Medications
• No medication has been FDA-approved for the treatment of NASH. Metformin, pioglitazone, liraglutide, semaglutide, and vitamin E have been studied in the following randomized trials:
• Metformin vs Vitamin E vs Placebo in Adolescents with NAFLD - TONIC trial
• Pioglitazone vs Vitamin E vs Placebo in Adults with NASH - PIVENS trial
• Liraglutide vs Placebo in Adults with NASH - PMID 26608256
• Semaglutide vs Placebo in Adults with NASH- PMID 33185364
• In the above trials, vitamin E and pioglitazone showed some benefit, while metformin had no effect
• Liraglutide and semaglutide were significantly better than placebo, but it's likely this was due to greater weight loss (liraglutide 5.5% vs placebo 0.7% | semaglutide 13% vs placebo 1%), as opposed to some NASH-specific mechanism
• No long-term studies have been performed that have evaluated hard outcomes like cirrhosis and mortality.

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• PRIMARY BILIARY CHOLANGITIS (PBC)

• Pathology
• Primary biliary cholangitis is believed to occur from abnormal immune regulation involving autoimmune antibodies that lead to the destruction of small and medium bile ducts. The condition has a strong genetic component, which may be related to inherited abnormalities in immune function. Antimitochondrial antibodies (AMAs) are present in over 95% of patients, and it is unclear why the biliary tree is particularly affected, as mitochondria and their antigens are ubiquitous in tissues.
• The disease is often asymptomatic, and 25% of cases are diagnosed incidentally on routine blood work. The main symptoms of PBC are fatigue (up to 80%) and itching (up to 70%). The rate of biliary destruction can vary widely between individuals. In longitudinal studies of untreated patients, the median time to extensive fibrosis was 2 years, and cirrhosis was present in 50% at 4 years. Untreated, PBC is fatal with a median survival of 5 - 8 years from symptom onset. [10,11]

• Epidemiology
• PBC is a rare disease that disproportionately affects women, with an estimated prevalence in the U.S. of 65.4 cases per 100,000 women and 12.1 cases per 100,000 men. The average age of onset in women is 39 years, with a range of 30 - 65 years. [10,11]

• Laboratories
• Antimitochondrial antibodies (AMAs) - AMAs are autoantibodies directed against the E2 component of the mitochondrial pyruvate dehydrogenase complex (PDC). AMAs are found in 95% of patients with PBC and are 98% specific for the disease. AMAs may appear several years before clinical PBC is present.

• Anti-smooth-muscle antibodies (ASMAs) - ASMAs are antibodies to cytoskeletal structures (e.g. actin, troponin, tropomyosin) found in smooth muscle cells. ASMAs, which are present in about 50% of PBC patients, are also found in autoimmune hepatitis. In PBC, low titers of ASMAs (< 1:80) are typically seen, whereas, in autoimmune hepatitis, higher titers are more common (> 1:80).[3,10,11]


• ALT, AST ALP, GGT, and bilirubin - significant elevations of ALP and GGT are common, while mild elevations of ALT and AST may be present. Bilirubin levels are typically normal in the early stages.


• Antinuclear antibodies (ANAs) - ANAs are found in 20 - 50% of patients with PBC, with subtypes anti-glycoprotein 210 (anti-gp210) and anti-sp100 being specific for PBC. ANAs are also present in autoimmune hepatitis and lupus. See antinuclear antibodies for more.

• Diagnosis
• The AASLD states that 2 of the following 3 must be present to make a diagnosis of PBC:
• Biochemical evidence of cholestasis based on ALP elevation
• Presence of AMA or other PBC-specific autoantibodies (antinuclear antibodies of the type anti-sp100 or anti-gp210)
• Histologic evidence of nonsuppurative destructive cholangitis and destruction of interlobular bile ducts [10]

• Treatment
• The primary treatment for PBC is ursodeoxycholic acid (Ursodiol), a naturally-occurring bile acid that normally makes up a small fraction of the human bile acid pool. Ursodiol increases the proportion of ursodeoxycholic acid in a dose-dependent manner until it becomes the major biliary acid, replacing toxic concentrations of endogenous hydrophobic acids that tend to accumulate in cholestatic liver disease. In PBC, ursodiol has been shown to improve liver chemistries and reduce the need for liver transplantation. Liver tests improve in 90% of patients within 6 - 9 months of therapy initiation, and 20% will have liver test normalization after 2 years.
• Ursodiol is marketed under the brand names Actigall® and URSO® 250. The recommended dose in PBC is 13 - 15 mg/day. [Actigall PI]
• Obeticholic acid (Ocaliva®), another drug approved for PBC, is an agonist at the hepatocyte FXR nuclear receptor. FXR stimulation suppresses bile acid synthesis and increases bile acid transport out of the cell. [Ocaliva PI]
• AASLD treatment recommendations for PBC
• Ursodiol in a dose of 13 to 15 mg/kg/day orally is recommended for patients with PBC who have abnormal liver enzyme values regardless of histologic stage
• For patients requiring bile acid sequestrants, ursodiol should be given at least 1 hour before or 4 hours after the bile acid sequestrant
• Biochemical response to ursodiol should be evaluated at 12 months after treatment initiation to determine whether patients should be considered for second-line therapy
• Patients who are inadequate responders to ursodiol should be considered for treatment with obeticholic acid, starting at 5 mg/day
• Fibrates can be considered as off-label alternatives for patients with PBC and inadequate response to ursodiol
• Use of obeticholic acid and fibrates is discouraged in patients with decompensated liver disease (Child-Pugh B or C) [10]

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• PRIMARY SCLEROSING CHOLANGITIS (PSC)

• Pathology
• PSC is an inflammatory condition where the cells that line the bile ducts (cholangiocytes) are injured by chronic inflammation. Over time, the biliary tree becomes scarred and multifocal strictures form that cause biliary dilation and cholestasis. In most cases, both the small and large biliary system is affected (90%). The buildup of bile acids is toxic to hepatocytes and eventually liver failure occurs.
• The cause of PSC is not completely understood, but it is thought to occur through a combination of genetic and environmental factors. PSC can also occur secondary to other conditions that damage the biliary tree. Causes of secondary PSC include direct trauma (e.g. surgery, ERCP), chemotherapy, ischemic cholangitis, inflammatory disorders (e.g. IgG4-related disease), graft-versus-host disease, and cancer (e.g. cholangiocarcinoma) to name a few.
• PSC has a strong association with inflammatory bowel disease (IBD) with up to 80% of PSC patients having concomitant IBD, typically ulcerative colitis. Patients with PSC are also at much greater risk of cholangiocarcinoma with an incidence as high as 20% over 30 years.
• Most patients with PSC are asymptomatic and only discover they have the disease after a workup for abnormal liver function tests [19,20]

• Epidemiology
• PSC is a rare disease with an estimated incidence of 0 - 1.3 cases/100,000 persons per year. Males are affected more than females (3:2), and the median age of diagnosis is 41 years. [19,20]

• Diagnosis
• A diagnosis of PSC requires the following:
• Laboratories consistent with cholestasis (elevated ALP +/- elevated ALT/AST)
• Characteristic bile duct changes (multifocal strictures and segmental dilatations) seen on MRCP or ERCP
• Exclusion of secondary causes [19]

• Treatment
• There is no effective treatment for PSC, and approximately 40% of patients will eventually require a liver transplant. Recurrence after transplant occurs in around 25% of patients.
• Because of the strong association with IBD and cholangiocarcinoma, routine screening for these conditions is recommended [19,20]

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• AUTOIMMUNE HEPATITIS (AIH)

• Pathology
• AIH occurs when dysfunctional immune regulation results in the development of autoantibodies to hepatocyte antigens. The origin of the immune dysfunction is multifactorial and includes genetic predisposition (HLA haplotypes B8, B14, DR3, DR4, and Dw3) and environmental triggers (e.g. HCV, HBV, HAV, EBV, and possibly drugs).
• Inflammatory destruction of hepatocytes leads to progressive portal fibrosis and if untreated, eventually cirrhosis
• AIH is divided into 2 subtypes - type 1 AIH and type 2 AIH. The subtypes differ by age and mode of presentation, laboratory features, and overlap with PBC and PSC. Type 1 AIH is the most common type in the U.S. (96% of adults). It typically presents in adults or peripubertal children, and it has an insidious onset. Its features may also overlap PSC and PBC. Type 2 AIH typically presents in children under 14 years of age. It can have an acute onset (40%), and its features do not typically overlap with PBC or PSC. ANAs and ASMAs are associated with type 1 and LKM antibodies are found in type 2. [12,13]

• Epidemiology
• AIH is a rare disease with an estimated prevalence of 0.1 - 1.2 cases per 100,000 among white individuals. AIH can occur at any age, and it has a bimodal peak incidence at 10 - 30 years and 40 - 60 years. Women are affected more than men (4:1 ratio), whites of northern European descent have the highest incidence, and chronic liver diseases like hepatitis C are present in 11 - 23% of affected individuals. [12,13]

• Laboratories
• ALT, AST ALP, and bilirubin - ALT and AST are elevated in 100% of patients with AIH at presentation with average values in the 200 - 300 U/L range. ALP and bilirubin are mild to moderately elevated in 80 - 90% of patients.


• Antinuclear antibodies (ANAs) - ANAs are present in 80% of white North American adults with AIH. ANAs in AIH are typically directed toward chromatin and ribonucleoproteins. ANAs are common in type 1 AIH and uncommon in type 2. ANAs are nonspecific and present in many other liver diseases (PSC - 29% | HCV - 26% | HBV - 32% | NAFLD - 34%). The presence of ASMAs with ANAs increases the probability of AIH as this combination of autoantibodies is seen in < 10% of liver diseases outside of AIH.


• Anti-smooth-muscle antibodies (ASMAs) - ASMAs are antibodies to cytoskeletal structures (eg, actin, troponin, tropomyosin) found in smooth muscle cells. ASMAs are found in about 63% of white North American adults with AIH. ASMAs are also seen in primary biliary cholangitis but at lower titers (< 1:80) when compared to AIH (> 1:80). The presence of ANAs with ASMAs increases the probability of AIH as this combination of autoantibodies is seen in < 10% of liver diseases outside of AIH.

• Anti-liver kidney microsomal antibody (LKM antibody) - LKM antibodies are autoantibodies directed toward cytochrome P450 2D6 which is found primarily in liver cells. LKM antibodies are mostly seen in type 2 AIH and are usually found in isolation without associated ANAs or ASMAs.


• Immunoglobulin G (IgG) titers - IgG levels are typically elevated in AIH, and the absence of elevated levels makes AIH unlikely. IgG levels are also used to monitor disease activity during treatment. [3,12,13]

• Diagnosis
• The diagnosis of AIH is based on a combination of histological and laboratory findings. It also requires the exclusion of other more common causes of liver disease.
• Diagnostic criteria from the AASLD are given below
• Criteria for the diagnosis of AIH include all of the following:
• Typical histological features on liver biopsy (interface hepatitis accompanied by plasma cell infiltration in 66% and lobular hepatitis in 47%)
• Elevated ALT and AST
• Elevated serum IgG level and/or positive ANA, ASMA, or LKM antibody
• Exclusion of viral, hereditary, metabolic, cholestatic, and drug-induced diseases that may resemble AIH [12]

• Treatment
• AIH is primarily treated with corticosteroids and azathioprine. Up to 80% of patients can achieve remission in 3 years with immunosuppressant therapy. An incomplete response is seen in 13% of patients, and approximately 10% of patients do not respond to treatment and have worsening of their disease.
• Corticosteroids are started initially and then gradually tapered depending on response. Azathioprine is added when considered safe and then continued indefinitely in most cases.
• Relapse is common if immunosuppressants are withdrawn. In studies, 46% of adults and 80% of children experienced relapse when therapy was withdrawn after ≥ 2 years of treatment. [12,13]

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• HEPATITIS B VIRUS (HBV)

• Epidemiology
• HBV infects approximately 3.5% of the world's population which translates to around 257 million infected people. Asia, the South Pacific, and Africa have the highest prevalence with approximately 6 - 7% infected. In the U.S., the prevalence of HBV infection is around 0.3%. Most people in the U.S. with HBV were born in foreign countries. The estimated prevalence of HBV among foreign-born people in the U.S. is 3 - 5%, and they account for 70% of the total infections in the U.S. [14,15,16,17]

• Pathology
• Most HBV infection occurs through perinatal transmission from mother to child. The virus is also passed through blood-to-blood contact (e.g. needles, transfusions, etc.) and sexual intercourse. Since the introduction of an effective vaccine in the 1980s, these routes of infection have become less common.
• The HBV itself does not appear to directly damage hepatocytes, and the long-term sequelae of cirrhosis and hepatocellular carcinoma appear to be related to the host's immune response to the infection.
• The clinical course of HBV infection varies widely between individuals with some people progressing to cirrhosis while others have lifelong chronic infections that do not cause hepatocellular damage or require treatment. Geography appears to play an important role in disease severity, even among untreated patients. In low-endemic regions, the incidence of HBV-related liver complications in untreated patients is as low as 1.2% over 16 years, whereas in high-endemic regions, the 5-year cumulative incidence of cirrhosis is as high as 38%.
• Spontaneous clearance of HBsAg occurs at an annual rate of 0.7 – 2.3%, and cumulative clearance rates can reach 33% over time [16,17]

• HBV risk factors
• Chronic liver disease - persons with hepatitis C, cirrhosis, fatty liver disease, alcoholic liver disease, autoimmune hepatitis, alanine aminotransferase (ALT) or aspartate aminotransferase (AST) level greater than twice upper limit of normal
• HIV infection
• Sexual exposure risk - sex partners of hepatitis B surface antigen [HBsAg]-positive persons; sexually active persons not in mutually monogamous relationships; persons seeking evaluation or treatment for a sexually transmitted infection; men who have sex with men
• Current or recent injection drug use
• Percutaneous or mucosal risk for exposure to blood - household contacts of HBsAg-positive persons; residents and staff of facilities for developmentally disabled persons; health care and public safety personnel with reasonably anticipated risk for exposure to blood or blood-contaminated body fluids; persons on maintenance dialysis, including in-center or home hemodialysis and peritoneal dialysis, and persons who are predialysis; patients with diabetes
• Incarceration
• Travel in countries with high or intermediate endemic hepatitis B (see screening below) [34]

• Screening recommendations for HBV
• The USPSTF, CDC, and ACP recommend screening the following individuals for HBV:
• U.S.-born persons not vaccinated as infants whose parents were born in regions with a high prevalence of HBV infection (≥ 8%), such as sub-Saharan Africa and southeast and central Asia. See the USPSTF HBV prevalence chart for country and region specific rates. (USPSTF)
• Persons born in countries and regions with a prevalence of HBV infection ≥ 2%. See the USPSTF HBV prevalence chart for country and region specific rates. (USPSTF, CDC/ACP)
• HIV-positive persons (USPSTF, CDC/ACP)
• Injection drug users (USPSTF, CDC/ACP)
• Men who have sex with men (USPSTF, CDC/ACP)
• Household and sexual contacts of persons with HBV infection (USPSTF, CDC/ACP)
• Persons requiring immunosuppressive therapy (CDC/ACP)
• Persons with end-stage renal disease (CDC/ACP)
• Blood and tissue donors (CDC/ACP)
• Persons with hepatitis C (CDC/ACP)
• Persons with elevated ALT levels (≥ 19 IU/L for women and ≥ 30 IU/L for men) (CDC/ACP)
• Incarcerated persons (CDC/ACP)
• Pregnant women (CDC/ACP)
• Infants born to HBV-infected mothers

• Laboratories
• Hepatitis B surface antigen (HBsAg) - HBsAg is part of the outer protein coat of the HBV. On average, it can be detected around 4 weeks after infection. The presence of HBsAg indicates an active infection, and a positive HBsAg for ≥ 6 months constitutes a chronic infection. Some labs offer a HBsAg quantitative analysis. This lab may be useful in patients who are being treated with interferon, but the AASLD does not recommend checking it otherwise.


• Hepatitis B surface antibody (Anti-HBs, HBsAb) - Anti-HBs measures antibodies to surface proteins on the HBV. Presence of Anti-HBs antibodies indicates past infection that has resolved or past immunization.


• Hepatitis B core antibody (Anti-HBc, HBcAb) - Anti-HBc measures antibodies to the core antigen of HBV. Anti-HBc antibodies can be divided into IgM and IgG types. IgM antibodies typically appear 4 - 8 weeks after infection, and they disappear around 32 weeks post-infection. The presence of IgM antibodies indicates an acute infection (within 6 months). IgG antibodies develop soon after IgM antibodies and persist for life.


• Hepatitis B envelope antigen (HBeAg) - Hepatitis B envelope antigen is derived from proteolytic cleavage of the HBV nucleocapsid. Its presence represents active HBV replication and a highly infectious state. HBeAg is only found when HBsAg is also present. Loss of HBeAg indicates a resolving infection.


• Hepatitis B envelope antibody (HBeAb) - HBeAb measures antibodies to hepatitis B envelope antigen. The presence of HBeAb is a marker of disease resolution, and it is associated with decreased infectivity and decreased risk of cirrhosis and hepatocellular carcinoma.


• Hepatitis B DNA (viral load) - HBV DNA measures the amount of HBV DNA in the serum, and it is a reliable marker of HBV replication. HBV DNA is detectable as early as one week after exposure/infection. HBV DNA levels are directly proportional to infectivity and disease activity, and therefore, they are used to monitor therapy and disease progression. [3,16,17]

• Interpreting HBV screening results
• When screening for HBV, it is typically recommended that a HBsAg, Anti-HBs antibody (HBsAb), and Anti-Hbc antibody (HBcAb) be tested. The table below shows how to interpret results from these labs.

• Treatment
• Once a chronic infection is established (HBsAg-positive for ≥ 6 months), the clinical course of HBV varies widely among individuals. Patients often fluctuate back and forth between periods of active disease (HBeAg-positive, ↑ HBV DNA, ↑ ALT) and inactive disease (HBeAg-negative, ↓ HBV DNA, ↓ ALT).
• Treatment recommendations are based on monitoring ALT, HBV DNA, HBeAg and results from liver fibrosis testing (liver biopsies or other noninvasive tests). The table below provides recommendations from the 2018 AASLD guidelines.

• Treatment duration
• Treatment can end when there is clearance of HBsAg. Clearance of HBsAg is uncommon so this endpoint typically means lifelong therapy.
• In HBeAg-positive patients without cirrhosis, treatment cessation can be considered when there is seroconversion to HBeAb followed by an additional 12 months of therapy.
• Patients who stop therapy should have HBsAg, HBV DNA, and ALT levels checked every 3 months for at least 1 year [16,17]

• Medications
• There are currently 4 medications approved for the treatment of HBV. Three of the drugs - entecavir, tenofovir disoproxil fumarate, and tenofovir alafenamide - are oral nucleoside analogues, and the other drug, pegylated interferon (Peg-IFN), is a subcutaneous injection. Peg-IFN is not widely used anymore because it has significant side effects and inferior efficacy when compared to the nucleoside analogues.
• The nucleoside analogues are highly effective at suppressing HBV DNA with undetectable levels being achieved in 60 - 75% of HBeAg-positive patients and > 90% of HBeAg-negative patients. Long-term therapy has been associated with regression of cirrhosis in up to 71% of patients.
• The table below gives prescribing highlights for each drug [16,17]

• Immunosuppressive therapies
• Patients with HBV infection who receive immunosuppressive therapies are at risk for worsening or reactivation of their HBV infection. In studies, reactivation of HBV infection has occurred in up to 53% of patients receiving anticancer therapy and up to 12.3% of patients receiving antirheumatic therapies. The AASLD recommendations for managing these patients are given below. [16]
• AASLD recommendations for immunosuppressive therapies
• HBsAg and anti-HBc (total or immunoglobulin G) testing should be performed in all persons before initiation of any immunosuppressive, cytotoxic, or immunomodulatory therapy
• HBsAg-positive, anti-HBc–positive patients should initiate anti-HBV prophylaxis before immunosuppressive or cytotoxic therapy
• HBsAg-negative, anti-HBc–positive patients could be carefully monitored with ALT, HBV DNA, and HBsAg with the intent for on-demand therapy, except for patients receiving anti-CD20 antibody therapy (e.g., rituximab) or undergoing stem cell transplantation, for whom anti-HBV prophylaxis is recommended
• When indicated, anti-HBV prophylaxis should be initiated as soon as possible before or, at the latest, simultaneously with the onset of immunosuppressive therapy. Once started, anti-HBV prophylaxis should continue during immunosuppressive therapy and for at least 6 months (or for at least 12 months for patients receiving anti-CD20 therapies) after completion of immunosuppressive therapy
• Therapy should be with a nucleoside analog
• For patients being monitored without prophylaxis, HBV DNA levels should be obtained every 1 - 3 months. Patients should be monitored for up to 12 months after cessation of anti-HBV therapy. [16]

• Prevention
• The HBV vaccine offers excellent protection against HBV, and it has been a part of the recommended routine vaccination schedule for infants since 1991. In 2022, the CDC started recommending that all adults aged 19 - 59 years be routinely vaccinated (see CDC adult immunization schedule). Other recommendations for vaccination and prevention from the AASLD are provided below.

• Pregnant women
• HBV vaccine is safe in pregnancy and pregnant women who are not immune or infected should be vaccinated
• Women who meet standard indications for HBV therapy should be treated. Women without standard indications but who have HBV DNA > 200,000 IU/mL in the second trimester should consider treatment to prevent mother-to-child transmission. Tenofovir disoproxil fumarate (Viread®) is considered safe in pregnancy.
• Newborns of HBV-infected mothers should receive HBIG and HBV vaccine at delivery and complete the recommended vaccination series. Infants of HBsAg-positive mothers should undergo postvaccination testing at 9 - 15 months of age.

• High-risk individuals
• Healthcare workers, sexual partners of persons with chronic HBV infection, chronic hemodialysis patients, and immunocompromised persons (including those with HIV) should be tested for their response to the vaccination 1 - 2 months after the last dose of vaccine
• For nonresponders to the initial vaccine series, a repeat 3-dose vaccination series is recommended, with a double dose used for immunocompromised patients, including those with cirrhosis
• Follow-up testing of vaccine responders is recommended annually for chronic hemodialysis patients
• Booster doses or revaccination are not recommended except if anti-HBs remains < 10 mIU/mL after initial vaccination of infants born to HBsAg-positive mothers, in HCWs, hemodialysis patients and other individuals who are immunocompromised [16]

• HBV occupational exposure
• The University of California at San Francisco (UCSF) provides up-to-date recommendations on HBV occupational exposure prophylaxis at the link below
• Recommendations for Occupational Exposures to HIV, Hep B, and Hep C
• They also offer free, rapid expert consultation by phone - UCSF consultation

• Hepatocellular carcinoma (HCC) screening
• Patients with HBV are at increased risk of HCC. Patients with cirrhosis are at the greatest risk. Studies have shown that patients with cirrhosis and HBV have a 5-year cumulative risk of HCC of 26 - 39%, and patients without cirrhosis have a risk of 3 - 4%. Nucleoside analog therapy reduces the risk to around 7- 14% in cirrhotics and 2 - 3.5% in non-cirrhotics.
• AASLD recommendations for HCC screening are given below [18]
• AASLD HCC screening recommendations
• All HBsAg-positive patients with cirrhosis should be screened with ultrasound examination with or without alpha fetoprotein (AFP) every 6 months
• HBsAg-positive adults at high risk for HCC (including Asian or black men over 40 years and Asian women over 50 years of age), persons with a first-degree family member with a history of HCC, or persons with HDV should be screened with US examination with or without AFP every 6 months
• There is insufficient data to identify high-risk groups for HCC in children. However, it is reasonable to screen HBsAg-positive children and adolescents with advanced fibrosis (F3) or cirrhosis and those with a first-degree family member with HCC using US examination with or without AFP every 6 months.
• For HBsAg-positive persons at high risk for HCC who are living in areas where US is not readily available, screening with AFP every 6 months should be performed [16]

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• HEMOCHROMATOSIS

• Pathology
• Hemochromatosis is a term that means excessive body iron, also called "iron overload." Iron overload can occur through a number of mechanisms including genetic disorders of iron regulation, ineffective erythropoiesis (e.g. thalassemia, aplastic anemia), chronic hemolysis (e.g. sickle cell disease), chronic transfusions, liver diseases (e.g. hepatitis, alcoholic liver disease), and malignancies. When the disorder is inherited genetically, it is called hereditary hemochromatosis (HH).
• The pathology behind HH is excessive iron absorption from the intestine secondary to a deficiency of hepcidin (see iron homeostasis illustration for more). Genetic defects in the gene that codes for the homeostatic iron regulator (HFE) protein have been identified as a primary cause of HH. HFE protein is involved in regulating hepcidin production and iron uptake by hepatocytes. Defective HFE protein can lead to a loss of iron regulation and iron overload.
• Excessive body iron is deposited in the liver, heart, pancreas, joints, and pituitary gland. Over time, the iron has a toxic effect on the surrounding tissue and organ failure can ensue. The liver is one of the main storage sites for body iron, and this makes it especially susceptible to toxicity from iron overload. Untreated HH can lead to cirrhosis and an increased risk of HCC. Pancreatic iron deposition is toxic to beta-islet cells and diabetes occurs in up to 23% of patients. Cardiac manifestations are uncommon (3.1%), but may present as cardiomyopathy, heart failure, and arrhythmias. Joint disease occurs most commonly in the second and third metacarpophalangeal joints and behaves similarly to osteoarthritis. Iron deposition in the skin stimulates melatonin production which can lead to "bronzing" of the skin and is the source of the term "bronze diabetes" used to describe the presentation of some HH patients. [21]

• Epidemiology
• The prevalence of HH is estimated to be around 1 in 200 - 400 persons. People of Irish and Scandinavian descent have the highest rates and Africans have the lowest. In men, HH tends to manifest between the ages of 40 - 60 years, and it is often more advanced than what is seen in women. Women typically present after menopause when the protective effect of menses ends. [21]

• Diagnosis
• HH is diagnosed through a combination of iron studies and genetic testing for HFE alleles. Once a diagnosis has been established, the degree of liver fibrosis can be assessed with liver biopsy or other noninvasive tests. Lab findings in HH are detailed in the table below. [3,21]

• Treatment
• The primary treatment for HH is therapeutic phlebotomy. If treatment is started before cirrhosis is present, patients with HH typically do well and have a normal lifespan. Patients with cirrhosis at presentation have a reduced lifespan and are at increased risk of HCC.
• Phlebotomy has been shown to improve liver fibrosis. It is unclear if it has an effect on cardiomyopathy. Phlebotomy does not improve diabetes or joint disorders. Skin bronzing slowly regresses with phlebotomy. [21]
• Phlebotomy recommendations from the ACG are presented below
• ACG Treatment Recommendations for HH
• In C282Y homozygotes, start therapy when transferrin saturation is ≥ 45% and ferritin is > 300 ng/ml in men and > 200 ng/ml in women. Patients with ferritin levels between 300 (200 women) - 1000 ng/ml are unlikely to have end-organ damage, but 35% of men and 22% of women in this range will progress to a ferritin level > 1000 ng/ml, so treatment is recommended.
• C282Y homozygotes with a normal ferritin at diagnosis are unlikely to develop clinically relevant iron overload later in life, and therefore, they can be monitored with serial assessment of liver aminotransferase and ferritin levels
• In phlebotomized patients, the goal serum ferritin level is 50 - 100 ng/ml while keeping hemoglobin levels ≥ 11 g/dl
• Ferritin levels should be checked monthly until goal levels are reached
• Initially, phlebotomy is done weekly, removing around 500 mL of blood with each session. Removal of 1000 ml can be done in patients who tolerate it.
• Once goal ferritin levels are achieved, phlebotomy is reduced to 3 - 4 times a year
• Iron and vitamin C supplements should be avoided
• Dietary iron restrictions are not necessary
• Chelation therapy is only recommended in patients who cannot tolerate phlebotomy [21]

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• ALPHA-1 ANTITRYPSIN DEFICIENCY

• Pathology
• Alpha-1 antitrypsin (AAT) is a protein produced in the liver that circulates freely. The main action of AAT is in the lungs, where it inactivates neutrophil elastase, an enzyme that helps neutrophils fight infections. When AAT is deficient, elastase activity is unopposed, and it attacks structural proteins in the lungs. Over time, the lungs lose their structural integrity, and emphysema develops (typically panlobular and basal).
• AAT deficiency occurs from genetic mutations in the SERPINA1 gene. Mutations can lead to decreased production of AAT or the production of dysfunctional AAT, which is seen in 95% of severe cases. Dysfunctional AAT accumulates in the liver, where it is toxic to hepatocytes. Liver disease from AAT deficiency manifests in the fourth or fifth decade of life, and 20 - 40% of patients will go on to develop cirrhosis. [22,33]

• Epidemiology
• The prevalence of AAT deficiency varies widely by population, and it is likely underdiagnosed. It is most common in individuals of European descent (1 in 1500 - 3500 persons) and uncommon in Asians. The mean age of diagnosis in severe deficiency is 46 years, but the disease often goes unrecognized with an average delay between first symptoms and diagnosis of 5 - 7 years. [22,23]

• Screening
• Since AAT deficiency can present as common lung disorders (COPD and asthma), it is often missed
• Professional guidelines recommend testing people with any of the following for ATT deficiency:
• COPD
• Liver disease
• Poorly-responsive asthma
• c-ANCA vasculitis (> 90% will have antibody to proteinase 3)
• Panniculitis (painful subcutaneous nodules)
• Bronchiectasis
• First-degree relative with AAT deficiency [22]

• Diagnosis
• AAT deficiency is diagnosed by measuring blood AAT levels. AAT is also an acute phase reactant, so a C-reactive protein level should be measured at the same time to evaluate for inflammation. An AAT level > 1.1 g/liter in the presence of a normal C-reactive protein makes AAT deficiency unlikely.
• Once AAT deficiency is established, phenotyping (identifies allele based on amount and type of AAT in blood) or genotyping should be performed to determine which type of genetic defect is present [3,22]

• Treatment
• The management of COPD and emphysema in AAT deficiency is the same as that for other causes. In patients who develop cirrhosis, HCC screening should be performed.
• In 1987, the FDA approved plasma purified AAT for the treatment of AAT deficiency. Plasma purified AAT is derived from a pool of human plasma donors, and it is infused once weekly. Observational studies have shown a beneficial effect, but data from randomized controlled trials is lacking. [22] The largest trial performed (N=180) found that AAT therapy probably did have a beneficial effect, although the evidence was not conclusive. [PMID 26026936]
• A study published in 2022 found that the RNA-interfering drug fazirsiran greatly reduced the production of mutant Z-AAT, which is responsible for the hepatotoxicity seen with the disease. [PMID 35748699]

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• WILSON DISEASE

• Pathology
• Wilson disease is a disorder of copper homeostasis. Copper is an essential metal that serves as a cofactor in enzymatic reactions. On average, a person consumes about 2 - 5 mg/day of copper, and most of it ends up being excreted in the bile. Copper is removed from the blood by the liver, where it is transported across hepatocytes and into the bile by a protein called metal-transporting P-type adenosine triphosphatase (ATPase). Some copper is also placed in a protein called ceruloplasmin that transports it to other parts of the body.
• In Wilson disease, genetic defects alter the function of ATPase, and copper excretion is reduced. Copper accumulates in the liver, and it is eventually released back into the bloodstream, where it deposits in other organs, most notably the brain, kidneys, and cornea of the eye.
• Copper accumulation is toxic to organs, and depending on the organ affected, Wilson disease can present in a variety of ways. In the liver, chronic inflammation and cirrhosis can develop. In the eyes, copper deposition in the cornea leads to the characteristic Kayser-Fleischer rings that encircle the iris. Neurologic symptoms from brain deposition are the presenting feature in 40 - 50% of patients and may include tremor, choreiform movements, gait disturbances, parkinsonian features, seizures, and psychiatric illness (e.g. depression, psychosis). [24,25]

• Epidemiology
• Wilson disease is a rare disease with an estimated prevalence of 30 cases per 1 million people [24]

• Diagnosis
• No single test is diagnostic for Wilson disease, so a diagnosis must be established through a combination of laboratory and clinical findings. The table below details the studies that are used to diagnose Wilson disease.

• Treatment
• Wilson disease is primarily treated with chelation therapy and zinc. Prior to chelation therapy, the disease was uniformly fatal. Chelation therapy has been shown to improve liver function in most patients (> 90%). Neurologic symptoms are not as responsive but still improve in a majority of patients (60%).
• D-Penicillamine (Cuprimine®, Depen®) and trientine (Syprine®) are the two chelating agents used for treatment. They work by binding copper in the blood and promoting its excretion in the kidneys. Zinc works by inhibiting the absorption of copper in the intestine. [24,25,26]

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• METAVIR SCORING

• Overview
• The Metavir scoring system is a histological grading system used to quantify the amount of liver damage present in a liver biopsy specimen. The Metavir score is sometimes used in treatment guidelines for various liver conditions (e.g. HBV).
• The Metavir system assigns 2 scores based on histological findings. One score is a fibrosis score (F) and the other score is a disease activity score (A). The chart below outlines the Metavir system.

• Reference [27]

Metavir activity score (A)	Finding
0	No activity
1	Mild activity
2	Moderate activity
3	Severe activity

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• CHILD-PUGH LIVER FAILURE CLASSIFICATION

• Overview
• The Child-Pugh classification for liver failure was originally described by Dr. Child and Dr. Turcotte
• Another doctor, Dr. Pugh, later modified it. Today, it is widely known as the Child-Pugh classification
• The system combines three laboratory values and two physical exam findings to assign a score
• The score is then used to categorize patients into three groups - A, B, and C
• Studies have shown that the Child-Pugh groups can be used to predict survival in liver disease [28]
• The steps below explain how the score is determined. An online calculator is available here - Child-Pugh online calculator


• Determining the score


• STEP 1 - Measure the following 5 variables and assign a score

• ^✝In patients with primary biliary cirrhosis, bilirubin is scored as follows:

Bilirubin (mg/dl)	Child-Pugh score
< 4	1
4 - 10	2
> 10	3

• STEP 2 - Add up the scores and classify according to the following

• Surgical mortality based on 12-year study published in 1997 involving abdominal surgery [31]
• Reference [28]

Total score	Child-pugh class	Expected mortality
5 - 6	A	5-year survival 90% Surgical mortality 10%
7 - 9	B	5-year survival 80% Surgical mortality 32%
≥ 10	C	More than 33% die within one year Surgical mortality 82%

• Encephalopathy stages
• A number of authors have devised encephalopathy scales over the years
• Most scales are adaptations of a scale developed in the 1950s by Adam and Foley
• The scale below is a brief adaptation of the Adam and Foley and Gitlin scale

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