Medical School · Year 2 · Gastrointestinal · includes a quiz and discussion video

Lecture 11: Liver Diseases

Unit 2.2: Gastrointestinal System

Learning Objectives

By the end of this lecture, students will be able to:

1. Describe the pathophysiology and management of viral hepatitis
2. Explain alcoholic and non-alcoholic fatty liver disease
3. Describe autoimmune and metabolic liver diseases
4. Explain the pathophysiology and complications of cirrhosis
5. Describe hepatocellular carcinoma risk factors and surveillance
6. Explain the evaluation and management of acute liver failure

Viral Hepatitis Overview

Viral hepatitis encompasses infections by five primary hepatotropic viruses, each with distinct characteristics regarding transmission, chronicity, and clinical outcomes. Understanding these differences guides prevention, diagnosis, and management.

Hepatitis A virus is an RNA virus transmitted through the fecal-oral route, typically via contaminated water or food. The incubation period ranges from two to six weeks. Infection is often asymptomatic, particularly in children, and is uniformly self-limited without progression to chronic hepatitis. Diagnosis relies on IgM anti-HAV for acute infection, while IgG anti-HAV indicates prior infection or vaccination conferring immunity. Management is supportive, and highly effective vaccines are available for prevention.

Hepatitis E virus, also an RNA virus with fecal-oral transmission, shares many characteristics with hepatitis A. However, hepatitis E carries particular importance in pregnant women, in whom infection can cause fulminant hepatic failure with mortality rates approaching twenty percent. Undercooked pork represents a significant transmission source in endemic areas. Chronic infection can occur in immunocompromised patients, treatable with ribavirin. Diagnosis uses anti-HEV IgM.

Hepatitis B and C viruses cause the major burden of chronic viral hepatitis worldwide and are discussed in subsequent sections. Hepatitis D virus is a defective RNA virus that requires hepatitis B surface antigen for its envelope and therefore occurs only as coinfection with hepatitis B or superinfection in chronic hepatitis B carriers. Coinfection typically resolves, while superinfection often produces accelerated liver disease progression.

<image>Panel A: Comparison table of five hepatitis viruses (HAV, HBV, HCV, HDV, HEV) showing genome type, transmission routes, incubation periods, chronicity rates, and vaccine availability. Panel B: World map depicting geographic distribution and endemic regions for each hepatitis virus with color-coded prevalence zones. Panel C: Clinical course diagrams for each virus illustrating ALT elevation patterns and resolution versus chronicity outcomes. Panel D: Long-term sequelae chart showing cirrhosis and hepatocellular carcinoma risk by virus type.</image>

Hepatitis B

Hepatitis B virus is a partially double-stranded DNA virus with unique replication involving a reverse transcriptase enzyme to generate viral DNA from an RNA intermediate. This replication strategy explains why nucleoside and nucleotide analogs effectively suppress viral replication. The virus demonstrates remarkable stability, surviving outside the body on surfaces for extended periods.

Three viral antigens have clinical importance. Hepatitis B surface antigen (HBsAg) indicates active infection, whether acute or chronic. Hepatitis B e antigen (HBeAg) is a secreted protein indicating high viral replication and high infectivity. Hepatitis B core antigen (HBcAg) resides in the viral nucleocapsid and is not detected in serum, though antibodies to it are measurable.

Serologic interpretation requires systematic evaluation of multiple markers. HBsAg positivity with anti-HBc IgM positivity indicates acute infection. HBsAg positivity with anti-HBc total positivity but anti-HBs negativity indicates chronic infection. HBsAg negativity with both anti-HBc and anti-HBs positivity indicates resolved infection with immunity. HBsAg negativity with anti-HBs positivity alone indicates vaccination. Isolated anti-HBc positivity (without HBsAg or anti-HBs) may represent the window period between acute infection resolution and antibody appearance, occult infection with low-level HBsAg, or false-positive result.

The natural history of chronic hepatitis B progresses through recognizable phases. The immune tolerant phase, seen in perinatally infected individuals, features high viral loads with normal ALT, reflecting immune tolerance to the virus. The immune active (HBeAg-positive) phase demonstrates elevated ALT as the immune system mounts a response, potentially causing liver inflammation. The inactive carrier state follows HBeAg seroconversion, with low viral loads and normal ALT. HBeAg-negative chronic hepatitis B represents reactivation with moderate viral loads and elevated ALT despite HBeAg negativity.

Treatment is indicated for immune active phases with evidence of significant hepatic inflammation or fibrosis. First-line therapies include nucleoside analogs (entecavir) and nucleotide analogs (tenofovir disoproxil fumarate or tenofovir alafenamide). These agents suppress viral replication effectively with high barriers to resistance and excellent safety profiles. Pegylated interferon offers finite-duration therapy but achieves lower response rates and causes more side effects. Treatment goals include sustained viral suppression, prevention of disease progression to cirrhosis, and reduction of hepatocellular carcinoma risk.

<image>Panel A: Hepatitis B viral structure diagram showing partially double-stranded DNA genome, reverse transcriptase, HBsAg envelope, HBcAg nucleocapsid, and HBeAg secreted protein with transmission routes. Panel B: Serologic interpretation grid displaying five clinical scenarios (acute infection, chronic infection, resolved immunity, vaccinated, isolated anti-HBc) with marker patterns for HBsAg, anti-HBs, anti-HBc, HBeAg, and HBV DNA. Panel C: Natural history phases diagram illustrating immune tolerant, immune active, inactive carrier, and HBeAg-negative chronic hepatitis B with corresponding ALT and HBV DNA levels. Panel D: Treatment algorithm showing first-line agents (entecavir, tenofovir), pegylated interferon alternative, and treatment goals.</image>

Hepatitis C

Hepatitis C virus is a positive-sense, single-stranded RNA virus characterized by high genetic variability due to error-prone replication. Six major genotypes exist, with geographic variation in prevalence. This variability has prevented vaccine development but fortunately has become less relevant with the advent of pan-genotypic direct-acting antiviral regimens.

Transmission occurs primarily through blood exposure. Injection drug use represents the most common current transmission route in developed countries. Blood transfusion was historically important but has been largely eliminated through screening implemented in 1992. Healthcare-associated transmission occurs through needlestick injuries and inadequate sterilization. Vertical transmission from mother to child occurs in approximately five percent of cases when the mother has detectable HCV RNA, higher with HIV coinfection. Sexual transmission is possible but less efficient than with hepatitis B.

Natural history following acute infection differs markedly from hepatitis A. Only fifteen to twenty-five percent of acutely infected individuals spontaneously clear the virus; the remaining seventy-five to eighty-five percent develop chronic infection. Among those with chronic infection, fifteen to thirty percent develop cirrhosis over twenty to thirty years. Cirrhotic patients face one to four percent annual risk of hepatocellular carcinoma. Chronic hepatitis C also produces extrahepatic manifestations including mixed cryoglobulinemia, membranoproliferative glomerulonephritis, and porphyria cutanea tarda.

Diagnosis begins with anti-HCV antibody testing, which indicates exposure but does not distinguish active from resolved infection. HCV RNA testing confirms active viremia. Genotype testing guides treatment duration, though pan-genotypic regimens have reduced its importance. Fibrosis assessment through transient elastography or serum-based scores (FIB-4) stages disease severity and identifies those at highest risk for complications.

Treatment with direct-acting antivirals has revolutionized hepatitis C management. These drugs target viral proteins essential for replication: NS3/4A protease, NS5A protein, and NS5B polymerase. Pan-genotypic regimens including sofosbuvir/velpatasvir and glecaprevir/pibrentasvir cure over ninety-five percent of patients with eight to twelve weeks of oral therapy. Sustained virologic response (SVR), defined as undetectable HCV RNA twelve weeks after completing treatment, represents cure. All patients with chronic hepatitis C should receive treatment unless limited life expectancy precludes benefit. Patients who achieve SVR but have pre-existing cirrhosis require ongoing hepatocellular carcinoma surveillance, as cancer risk persists despite viral eradication.

<image>Panel A: Hepatitis C viral structure with positive-sense single-stranded RNA genome, six major genotypes shown on a world map, and high mutation rate characteristics. Panel B: Transmission routes ranked by efficiency (injection drug use, blood transfusion, needlestick, vertical, sexual) and natural history flowchart showing acute infection outcomes and chronic disease progression rates. Panel C: Diagnostic algorithm from anti-HCV antibody testing through HCV RNA confirmation, genotyping, and fibrosis staging. Panel D: Direct-acting antiviral treatment panel showing drug targets (NS3/4A, NS5A, NS5B), regimens, 8-12 week duration, greater than 95% SVR cure rate, and post-SVR monitoring for cirrhotics.</image>

Alcoholic Liver Disease

Alcoholic liver disease encompasses a spectrum of hepatic injury ranging from simple steatosis to cirrhosis, reflecting cumulative alcohol-induced damage. The pattern and amount of alcohol consumption, along with individual susceptibility factors, determine disease progression.

Risk factors for developing alcoholic liver disease include quantity and duration of alcohol consumption. Sustained intake exceeding forty to eighty grams daily in men (roughly three to six standard drinks) and twenty to forty grams daily in women creates significant risk. Daily drinking carries higher risk than episodic binge drinking. Genetic factors including polymorphisms in alcohol dehydrogenase and aldehyde dehydrogenase influence susceptibility. Comorbidities including hepatitis C coinfection, obesity, and iron overload accelerate liver injury.

The disease spectrum begins with alcoholic steatosis (fatty liver), characterized by hepatocyte triglyceride accumulation. This stage is typically asymptomatic and fully reversible with abstinence. Alcoholic steatohepatitis adds inflammation to fat accumulation, with hepatocyte injury manifested by ballooning degeneration and characteristic Mallory-Denk bodies (intracytoplasmic eosinophilic inclusions of aggregated cytokeratins). Neutrophilic inflammation predominates. Progressive fibrosis leads ultimately to cirrhosis, which becomes irreversible though abstinence may still allow some regression.

Alcoholic hepatitis represents a clinical syndrome of acute-on-chronic liver injury with characteristic presentation. Patients develop jaundice, often with fever and tender hepatomegaly. Laboratory findings demonstrate the AST:ALT ratio exceeding 2:1, a pattern reflecting alcohol-related mitochondrial injury and pyridoxine deficiency reducing ALT synthesis. AST elevation is typically modest, usually below 300 U/L; higher values should prompt consideration of alternative diagnoses. Leukocytosis is common.

Severity assessment guides prognosis and treatment decisions. The Maddrey discriminant function (DF) calculates as 4.6 × (patient's prothrombin time minus control PT in seconds) plus total bilirubin in mg/dL. A DF of 32 or greater indicates severe alcoholic hepatitis with approximately thirty-five percent one-month mortality. The MELD score provides additional prognostic information.

Treatment of alcoholic liver disease begins with abstinence, the single most important intervention at any disease stage. Nutritional support addresses common deficiencies; protein intake should be maintained (1.2-1.5 g/kg/day) to support hepatic regeneration, and thiamine supplementation prevents Wernicke encephalopathy. For severe alcoholic hepatitis (DF ≥32), prednisolone 40 mg daily for 28 days improves short-term survival if no contraindications (active infection, gastrointestinal bleeding, renal failure) exist. The Lille score at day seven identifies treatment responders who should continue the full course. Pentoxifylline is no longer recommended based on negative trial data. Liver transplantation remains controversial for alcoholic hepatitis but is offered at selected centers for patients with excellent support systems, even without the traditional six-month abstinence requirement.

<image>Panel A: Disease spectrum progression from normal liver through steatosis, steatohepatitis with Mallory-Denk bodies, fibrosis, and cirrhosis, with reversibility indicated at early stages. Panel B: Risk factors diagram showing alcohol consumption thresholds for men and women, genetic polymorphisms (ADH/ALDH), and comorbidities (HCV, obesity, iron overload). Panel C: Alcoholic hepatitis clinical features including jaundice, fever, tender hepatomegaly, AST:ALT ratio greater than 2:1, and leukocytosis. Panel D: Severity assessment and treatment algorithm with Maddrey discriminant function formula, prednisolone indications and contraindications, and Lille score responder assessment at day 7.</image>

Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD) to reflect its metabolic basis, has become the most common liver disease worldwide. The terminology change emphasizes the positive diagnostic criteria based on metabolic risk factors rather than exclusion of alcohol.

NAFLD encompasses a spectrum from simple steatosis (hepatic fat accumulation exceeding five percent of hepatocytes without inflammation) to non-alcoholic steatohepatitis (NASH, now termed metabolic dysfunction-associated steatohepatitis or MASH), which adds hepatocyte injury and inflammation to steatosis. NASH carries risk of progression to fibrosis and cirrhosis.

Epidemiology reflects the obesity epidemic. Prevalence reaches twenty-five to thirty percent of adults in Western countries, making NAFLD the most common liver disease. Risk factors align with metabolic syndrome: obesity (present in seventy-five to ninety percent of NAFLD patients), type 2 diabetes, dyslipidemia, and hypertension. Among those with NAFLD, twenty to thirty percent develop NASH, and of those with NASH, ten to twenty percent progress to cirrhosis. NAFLD-related cirrhosis is becoming an increasingly common indication for liver transplantation.

Pathophysiology centers on insulin resistance. In the insulin-resistant state, peripheral lipolysis is not suppressed appropriately, delivering excess free fatty acids to the liver. Hepatic de novo lipogenesis is paradoxically enhanced. The resulting lipid accumulation renders hepatocytes susceptible to oxidative stress and lipid peroxidation. Inflammatory mediators including tumor necrosis factor-alpha and interleukin-6 promote hepatocyte injury. Alterations in the gut microbiome and the gut-liver axis contribute through increased intestinal permeability and delivery of bacterial products to the liver.

Diagnosis is often suspected based on incidentally discovered elevated aminotransferases or hepatic steatosis on imaging performed for other reasons. Ultrasound detects steatosis as increased echogenicity but cannot distinguish NASH from simple steatosis. Transient elastography measures liver stiffness as a non-invasive fibrosis assessment. The FIB-4 index, calculated from age, AST, ALT, and platelet count, stratifies patients by fibrosis risk. Liver biopsy remains the gold standard for confirming NASH and staging fibrosis but is invasive and subject to sampling variability.

Treatment prioritizes lifestyle modification. Weight loss of seven to ten percent improves steatosis, inflammation, and even fibrosis in NASH patients. Combined dietary modification (caloric restriction, avoiding fructose-sweetened beverages) and exercise achieve better outcomes than either alone. Pharmacotherapy options are expanding. Pioglitazone, a thiazolidinedione insulin sensitizer, improves liver histology in NASH patients with or without diabetes, though weight gain limits its use. Vitamin E (800 IU daily) benefits non-diabetic NASH patients. GLP-1 receptor agonists produce weight loss and appear to improve NASH histology. Resmetirom, a thyroid hormone receptor-beta agonist, became the first medication specifically approved for NASH with fibrosis in 2024. Bariatric surgery effectively improves NASH in morbidly obese patients.

<image>Panel A: NAFLD/MASLD disease spectrum from normal liver through simple steatosis, NASH/MASH with ballooning hepatocytes, fibrosis, and cirrhosis, with progression rates between stages. Panel B: Epidemiology showing 25-30% prevalence and association with metabolic syndrome components (obesity, type 2 diabetes, dyslipidemia, hypertension). Panel C: Pathophysiology diagram illustrating insulin resistance driving peripheral lipolysis, hepatic lipogenesis, oxidative stress, inflammation, and gut-liver axis dysfunction. Panel D: Diagnostic and treatment algorithm including FIB-4, elastography, lifestyle intervention targets (7-10% weight loss), and pharmacotherapy options (pioglitazone, vitamin E, GLP-1 agonists, resmetirom).</image>

Autoimmune and Metabolic Liver Diseases

Autoimmune hepatitis results from immune-mediated attack on hepatocytes, presenting with a bimodal age distribution affecting young women and older adults of both sexes. Type 1 autoimmune hepatitis, the more common form, is characterized by antinuclear antibodies and anti-smooth muscle antibodies. Type 2, occurring primarily in children, features anti-liver-kidney microsomal type 1 antibodies (anti-LKM1).

Clinical presentation ranges from asymptomatic aminotransferase elevation discovered incidentally to acute hepatitis mimicking viral infection to chronic liver disease with established cirrhosis. Laboratory findings demonstrate marked elevation of aminotransferases and elevated serum immunoglobulin G. Histology shows interface hepatitis (inflammation at the junction of portal tract and parenchyma) with prominent plasma cell infiltration.

Treatment with immunosuppression produces excellent outcomes. Initial therapy combines prednisone with azathioprine, with the azathioprine enabling steroid taper. Most patients require long-term maintenance immunosuppression, though a minority achieve sustained remission allowing treatment withdrawal.

Primary biliary cholangitis (formerly primary biliary cirrhosis) affects primarily middle-aged women and targets small intrahepatic bile ducts. Autoimmune destruction causes progressive cholestasis. The anti-mitochondrial antibody (AMA), present in over ninety percent of patients, is the serologic hallmark. Elevated alkaline phosphatase with relatively preserved aminotransferases creates a cholestatic biochemical pattern. Pruritus is often the most troublesome symptom. Histologically, granulomatous destruction of bile ducts is characteristic. Treatment with ursodeoxycholic acid improves biochemistry and delays disease progression. Obeticholic acid, a farnesoid X receptor agonist, provides second-line therapy.

Primary sclerosing cholangitis involves fibrotic stricturing of medium and large bile ducts, affecting predominantly young men. The association with inflammatory bowel disease is strong, with seventy to eighty percent of PSC patients having ulcerative colitis (though only a small percentage of ulcerative colitis patients develop PSC). Elevated alkaline phosphatase is the typical finding, with p-ANCA positive in approximately seventy percent. Magnetic resonance cholangiopancreatography demonstrates the characteristic beaded appearance of irregular stricturing and dilation of bile ducts. No medical therapy has proven to alter disease progression. Cholangiocarcinoma develops in ten to fifteen percent of patients, mandating surveillance. Liver transplantation is the definitive treatment, though PSC can recur in the allograft.

Hereditary hemochromatosis results from HFE gene mutations, most commonly C282Y, causing inappropriately increased intestinal iron absorption. Iron accumulates in the liver, heart, pancreas, pituitary, and joints, producing a constellation of organ dysfunction. Elevated serum ferritin and transferrin saturation exceeding forty-five percent prompt genetic testing. Treatment with regular phlebotomy depletes iron stores and prevents progression of organ damage if instituted before cirrhosis develops.

Wilson disease results from ATP7B gene mutation impairing biliary copper excretion. Copper accumulates in the liver, brain, and cornea. Presentation typically occurs before age forty with liver disease, neuropsychiatric manifestations, or both. Kayser-Fleischer rings, representing copper deposition in Descemet's membrane of the cornea, are present in most patients with neurologic involvement. Laboratory findings include low serum ceruloplasmin and elevated twenty-four-hour urine copper. Treatment employs copper chelation with D-penicillamine or trientine, or zinc supplementation to block intestinal copper absorption.

<image>Panel A: Autoimmune hepatitis showing hepatocyte targeting with plasma cell infiltration, ANA/ASMA or anti-LKM1 markers, and steroid treatment approach. Panel B: Primary biliary cholangitis and primary sclerosing cholangitis compared, showing small duct destruction with AMA marker and UDCA treatment for PBC versus large duct stricturing with IBD association and cholangiocarcinoma risk for PSC. Panel C: Hereditary hemochromatosis illustrating HFE C282Y mutation, iron deposition in liver, heart, pancreas, joints, and pituitary, with elevated ferritin and phlebotomy treatment. Panel D: Wilson disease showing ATP7B mutation, copper deposition in liver, brain, and cornea with Kayser-Fleischer rings, low ceruloplasmin, and chelation treatment.</image>

Cirrhosis: Pathophysiology and Classification

Cirrhosis represents the end stage of chronic liver injury regardless of etiology, characterized by diffuse fibrosis with transformation of normal hepatic architecture into regenerative nodules. While historically considered irreversible, evidence now demonstrates that regression can occur with effective treatment of the underlying cause.

Etiologies reflect the prevalence of various liver diseases. Alcohol accounts for thirty to forty percent of cirrhosis cases in Western countries. Chronic hepatitis C contributes twenty-five to thirty percent, though this proportion is declining with widespread direct-acting antiviral treatment. NAFLD/MASLD now represents twenty to twenty-five percent and is increasing. Hepatitis B causes five to ten percent. The remainder results from autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis, hereditary hemochromatosis, Wilson disease, and other less common conditions.

Pathophysiology begins with hepatic stellate cell activation. These cells, normally quiescent and storing vitamin A, transform into proliferative myofibroblasts upon liver injury. Activated stellate cells produce excessive extracellular matrix proteins, particularly collagen types I and III, leading to progressive fibrosis. The fibrosis distorts hepatic architecture, creating regenerative nodules that lack normal lobular organization. This architectural disruption impairs sinusoidal blood flow, creating increased intrahepatic vascular resistance and portal hypertension. Progressive hepatocyte loss reduces synthetic capacity. Portosystemic shunting allows blood to bypass hepatocytes, contributing to hyperammonemia and hepatic encephalopathy, and enabling splanchnic vasodilation that triggers the hyperdynamic circulatory state.

Clinical classification distinguishes compensated from decompensated cirrhosis. Compensated cirrhosis may be asymptomatic or present with non-specific symptoms such as fatigue. Decompensated cirrhosis is defined by the development of complications: ascites, variceal hemorrhage, hepatic encephalopathy, or jaundice. The transition from compensated to decompensated status marks a significant prognostic threshold.

Prognostic scoring systems quantify disease severity. The Child-Turcotte-Pugh score incorporates five variables: albumin, bilirubin, INR, ascites severity, and encephalopathy grade. Class A (5-6 points) represents compensated cirrhosis with good hepatic reserve. Class B (7-9 points) indicates significant hepatic compromise. Class C (10-15 points) signifies decompensated disease with poor prognosis. The Model for End-Stage Liver Disease (MELD) score, calculated from bilirubin, INR, and creatinine, provides a continuous measure of disease severity. MELD score determines organ allocation priority for liver transplantation.

<image>Panel A: Etiologies pie chart with alcohol (30-40%), HCV (25-30%), NAFLD (20-25%), HBV (5-10%), and other causes including autoimmune and metabolic liver diseases. Panel B: Pathophysiology flowchart from chronic liver injury through stellate cell activation and collagen deposition to portal hypertension, synthetic failure, and portosystemic shunting. Panel C: Compensated versus decompensated cirrhosis comparison with defining features (ascites, variceal hemorrhage, encephalopathy, jaundice) and survival implications. Panel D: Prognostic scoring systems showing Child-Pugh classification (A, B, C) with five parameters and MELD formula with transplant priority implications.</image>

Complications of Cirrhosis

Portal hypertension underlies most cirrhotic complications. Hepatic venous pressure gradient, the difference between wedged and free hepatic venous pressures, normally measures below 5 mmHg. Clinically significant portal hypertension exists when this gradient exceeds 10 mmHg, the threshold for variceal development. Portal hypertension drives collateral vessel formation at sites of portosystemic communication.

Gastroesophageal varices develop at the esophagogastric junction, where the left gastric (coronary) vein connects to the systemic esophageal venous plexus. Approximately fifty percent of cirrhotic patients develop varices, and about thirty percent of those with large varices experience hemorrhage within two years. Variceal hemorrhage is life-threatening, with six-week mortality of fifteen to twenty percent. Primary prophylaxis to prevent first bleeding employs non-selective beta-blockers (propranolol or nadolol), which reduce portal pressure, or endoscopic variceal ligation. Acute variceal bleeding requires resuscitation, vasoactive drugs (octreotide or terlipressin), prophylactic antibiotics, and urgent endoscopy with band ligation. Transjugular intrahepatic portosystemic shunt (TIPS) provides rescue therapy for refractory bleeding.

Ascites, the accumulation of fluid in the peritoneal cavity, results from portal hypertension, hypoalbuminemia, and renal sodium retention. The serum-ascites albumin gradient (SAAG), calculated as serum albumin minus ascites albumin, of 1.1 g/dL or greater indicates portal hypertension as the cause. Management begins with sodium restriction to less than 2 grams daily and diuretics, typically spironolactone with or without furosemide. Refractory ascites requires serial large-volume paracentesis or TIPS placement.

Spontaneous bacterial peritonitis represents infection of ascitic fluid without identifiable intra-abdominal source, occurring due to bacterial translocation and impaired immune defenses. Diagnosis requires ascitic fluid analysis with polymorphonuclear cell count exceeding 250 cells per microliter. Treatment employs empiric third-generation cephalosporins, with albumin infusion reducing mortality. Patients who survive SBP require secondary prophylaxis with norfloxacin or trimethoprim-sulfamethoxazole.

Hepatic encephalopathy reflects brain dysfunction due to failure of hepatic ammonia clearance and portosystemic shunting of gut-derived neurotoxins. Clinical manifestations range from subtle cognitive impairment (minimal hepatic encephalopathy) through confusion and asterixis (overt encephalopathy) to coma. Precipitants include gastrointestinal bleeding, infection, constipation, electrolyte disturbances, sedating medications, and dietary protein excess. Treatment involves identifying and correcting precipitants, lactulose titrated to two to three soft bowel movements daily to trap ammonia in the gut lumen, and rifaximin to reduce ammonia-producing bacteria.

Hepatorenal syndrome describes functional renal failure in cirrhosis resulting from extreme splanchnic vasodilation and renal vasoconstriction. Type 1, now termed HRS-AKI, features rapid deterioration with high short-term mortality. Type 2, now termed HRS-NAKI, progresses more gradually, typically in the setting of refractory ascites. Treatment combines albumin infusion with vasoconstrictors (terlipressin, norepinephrine, or midodrine plus octreotide) to improve effective arterial volume.

<image>Panel A: Portal hypertension as the central mechanism (HVPG greater than 10 mmHg) with variceal bleeding management including prophylaxis options, acute bleeding algorithm, and TIPS rescue therapy. Panel B: Ascites management showing SAAG calculation, treatment ladder (sodium restriction, diuretics, paracentesis, TIPS), and spontaneous bacterial peritonitis diagnosis and treatment. Panel C: Hepatic encephalopathy grades I-IV with precipitants checklist and treatment with lactulose ammonia-trapping mechanism and rifaximin. Panel D: Hepatorenal syndrome pathophysiology showing splanchnic vasodilation and renal vasoconstriction, HRS-AKI versus HRS-NAKI distinction, and treatment with albumin plus vasoconstrictors.</image>

Hepatocellular Carcinoma

Hepatocellular carcinoma develops predominantly in the setting of chronic liver disease, making surveillance of at-risk populations essential. Cirrhosis of any etiology confers HCC risk, with one to four percent annual incidence in compensated cirrhosis. Among the etiologies, hepatitis B carries particular importance because it can cause HCC even without cirrhosis through direct oncogenic mechanisms. Hepatitis C-related cirrhosis and alcohol-related cirrhosis carry substantial risk. NAFLD-related HCC incidence is increasing, paralleling the metabolic disease epidemic. Aflatoxin B1 exposure (from Aspergillus mold contaminating stored grains) causes characteristic p53 mutations and contributes significantly in endemic regions.

Surveillance recommendations target patients at sufficient risk to justify screening. All patients with cirrhosis should undergo surveillance. Chronic hepatitis B patients without cirrhosis require surveillance if they have significant risk factors: Asian men over 40 and Asian women over 50, African or North American blacks, family history of HCC, or significant fibrosis. The surveillance protocol employs ultrasound with or without alpha-fetoprotein measurement every six months. Alpha-fetoprotein alone is insufficient due to limited sensitivity, though elevated levels prompt further evaluation.

Diagnosis in cirrhotic patients relies primarily on imaging characteristics. The Liver Imaging Reporting and Data System (LI-RADS) standardizes CT and MRI interpretation. The hallmark imaging feature is arterial phase hyperenhancement (reflecting HCC's hepatic arterial blood supply) with washout in the portal venous or delayed phases (reflecting rapid contrast washout from the abnormal tumor vasculature). Lesions meeting these criteria in cirrhotic patients can be diagnosed as HCC without biopsy. Lesions with atypical features may require biopsy for definitive diagnosis.

Treatment selection follows the Barcelona Clinic Liver Cancer (BCLC) staging system, which incorporates tumor extent, liver function, and performance status. Very early (BCLC 0) and early stage (BCLC A) disease is amenable to curative treatment: surgical resection in patients with preserved liver function and limited portal hypertension, ablation (radiofrequency or microwave) for small tumors not amenable to resection, or liver transplantation. The Milan criteria for transplantation (single tumor ≤5 cm or up to three tumors each ≤3 cm, without macrovascular invasion or extrahepatic spread) identify patients with acceptable post-transplant outcomes.

Intermediate stage disease (BCLC B) with larger or multifocal tumors but preserved function is treated with transarterial chemoembolization (TACE), which delivers chemotherapy directly to the tumor while embolizing its blood supply. Advanced stage disease (BCLC C) with portal vein invasion, lymph node involvement, or extrahepatic spread receives systemic therapy. First-line treatment combines atezolizumab (PD-L1 inhibitor) with bevacizumab (anti-VEGF antibody). Alternative regimens include tyrosine kinase inhibitors (sorafenib, lenvatinib). Immunotherapy alone with durvalumab plus tremelimumab provides another first-line option. Terminal stage disease (BCLC D) with severe liver decompensation or poor performance status receives supportive care.

<image>Panel A: Risk factors diagram with cirrhosis as the central node connecting to etiology-specific HCC risks (HBV, HCV, alcohol, NAFLD, aflatoxin) with annual incidence rates. Panel B: Surveillance protocol showing eligible populations, ultrasound with or without AFP every 6 months, and diagnostic pathway for abnormal findings. Panel C: Imaging characteristics illustrating arterial phase hyperenhancement and portal venous phase washout with LI-RADS classification categories. Panel D: BCLC staging and treatment algorithm from very early/early stage (resection, ablation, transplant with Milan criteria) through intermediate (TACE), advanced (systemic therapy), and terminal (supportive care).</image>

Acute Liver Failure

Acute liver failure represents a rare but life-threatening syndrome defined by coagulopathy (INR ≥1.5) and hepatic encephalopathy occurring in a patient without pre-existing liver disease, with illness duration of less than twenty-six weeks. The timeframe of symptom-to-encephalopathy onset distinguishes subtypes with different prognoses: hyperacute (less than seven days) carries better spontaneous survival than acute (seven to twenty-one days), which is better than subacute (twenty-one to twenty-six days).

Etiologies vary geographically. In the United States and United Kingdom, acetaminophen toxicity accounts for approximately fifty percent of cases. Therapeutic misadventure (exceeding recommended doses often with concurrent alcohol use or fasting) is more common than intentional overdose. Idiosyncratic drug reactions comprise ten to fifteen percent, with numerous agents implicated. Viral hepatitis causes ten to fifteen percent, with hepatitis B most common (hepatitis A rarely causes acute liver failure). Autoimmune hepatitis accounts for about five percent. Ischemic hepatitis from circulatory collapse contributes about five percent. Wilson disease presents rarely but with a distinct fulminant course including Coombs-negative hemolytic anemia. Pregnancy-related causes include acute fatty liver of pregnancy and HELLP syndrome. Fifteen to twenty percent remain indeterminate despite evaluation.

Clinical manifestations reflect multisystem involvement. Hepatic failure produces jaundice and profound coagulopathy; however, coagulation factor deficiency should not be corrected with fresh frozen plasma unless active bleeding occurs, as this obscures a critical prognostic marker. Cerebral edema, developing due to ammonia-induced astrocyte swelling, causes the most feared complication. Encephalopathy progresses from subtle confusion to coma. Cardiovascular manifestations include a hyperdynamic circulation with vasodilation and hypotension. Acute kidney injury occurs commonly. Metabolic derangements include hypoglycemia from impaired gluconeogenesis and lactic acidosis. Susceptibility to infection is markedly increased.

Management requires intensive care unit admission with aggressive supportive care. Cerebral edema management includes head elevation, avoidance of agitation and hyponatremia, and consideration of intracranial pressure monitoring in grade 3-4 encephalopathy. Hypertonic saline and mannitol treat elevated intracranial pressure. Hemodynamic support with vasopressors may be necessary. Renal replacement therapy addresses renal failure and assists ammonia clearance. Glucose infusion prevents hypoglycemia.

Etiology-specific treatment is critical. N-acetylcysteine (NAC) is highly effective for acetaminophen toxicity when administered early; the Rumack-Matthew nomogram guides decisions in single-time-point ingestions. Importantly, NAC also improves outcomes in non-acetaminophen acute liver failure, likely through improving microcirculation and free radical scavenging, and should be administered in indeterminate cases. Pregnancy-related acute liver failure requires delivery. Wilson disease is treated with plasmapheresis and copper chelation but typically requires urgent transplantation.

Liver transplantation provides the only definitive treatment for irreversible acute liver failure. The King's College Criteria guide transplant decision-making, with separate criteria for acetaminophen and non-acetaminophen etiologies. For acetaminophen cases, arterial pH below 7.3 after resuscitation, or the combination of grade 3-4 encephalopathy with INR greater than 6.5 and creatinine above 3.4 mg/dL, predicts death without transplantation. For non-acetaminophen cases, INR above 6.5 alone, or any three of the following (age under 10 or over 40, unfavorable etiology, jaundice-to-encephalopathy interval over seven days, bilirubin above 17.5 mg/dL, INR above 3.5), indicates need for transplantation. Early contact with a transplant center is essential.

<image>Panel A: Acute liver failure definition criteria (INR 1.5 or greater, encephalopathy, no prior liver disease, less than 26 weeks) with timeframe subtypes and etiology pie chart showing acetaminophen (50%), drug reactions, viral hepatitis, and other causes. Panel B: Multisystem manifestations diagram covering cerebral edema, cardiovascular changes, coagulopathy, acute kidney injury, hypoglycemia, and infection susceptibility. Panel C: Management algorithm from ICU admission through supportive care, etiology-specific treatment with N-acetylcysteine, and transplant evaluation. Panel D: King's College Criteria decision tool for acetaminophen and non-acetaminophen etiologies with threshold values for transplant consideration.</image>

Summary

Viral hepatitis includes fecal-oral transmitted HAV and HEV (self-limited, no chronicity except HEV in immunocompromised) and blood-borne HBV and HCV (significant chronicity). Hepatitis B serologic interpretation distinguishes acute infection, chronic infection, resolved immunity, and vaccination. Hepatitis C is curable with direct-acting antivirals achieving greater than ninety-five percent sustained virologic response.

Alcoholic liver disease progresses from steatosis through steatohepatitis to cirrhosis, with AST:ALT ratio exceeding 2:1. Severe alcoholic hepatitis (Maddrey DF ≥32) may respond to prednisolone. NAFLD/MASLD is the most common liver disease, closely linked to metabolic syndrome, with lifestyle modification achieving seven to ten percent weight loss as primary treatment.

Autoimmune hepatitis responds to immunosuppression. Primary biliary cholangitis targets small bile ducts with anti-mitochondrial antibodies and responds to ursodeoxycholic acid. Primary sclerosing cholangitis affects medium and large ducts, associates with inflammatory bowel disease, and has no effective medical therapy. Hemochromatosis requires phlebotomy; Wilson disease requires copper chelation.

Cirrhosis represents diffuse fibrosis with regenerative nodules, classified as compensated or decompensated (ascites, variceal hemorrhage, encephalopathy, jaundice). Child-Pugh and MELD scores quantify severity. Portal hypertension drives complications including varices (primary prophylaxis with beta-blockers or banding), ascites (sodium restriction, diuretics), spontaneous bacterial peritonitis (cephalosporins), hepatic encephalopathy (lactulose, rifaximin), and hepatorenal syndrome (albumin plus vasoconstrictors).

Hepatocellular carcinoma develops predominantly in cirrhosis with one to four percent annual incidence. Surveillance employs ultrasound every six months. Diagnosis relies on arterial enhancement with washout on imaging. BCLC staging guides treatment from curative intent (surgery, ablation, transplant) through TACE to systemic therapy.

Acute liver failure features coagulopathy and encephalopathy without prior liver disease. Acetaminophen causes fifty percent in the United States. N-acetylcysteine benefits both acetaminophen and non-acetaminophen cases. King's College Criteria guide transplant decisions.

Key Terms

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