Description

• Inflammation of the liver owing to infectious, toxic, and autoimmune disorders:
  • Progression from hepatocellular injury (hepatitis) to scarring (cirrhosis)

Etiology

• Unknown etiology in 5–10% of acute and chronic hepatitis cases and up to 50% in fulminant hepatic failure (FHF)
• Infection is the most common etiology of acute hepatitis
• Hepatitis A (HAV):
  • Transmission: Fecal–oral
  • Incubation period: 15–45 d
  • FHF in 0.1%
  • No chronic phase:
    • 10% will have a relapsing course over months
• Hepatitis B (HBV):
  • Transmission: Percutaneous exposure to bodily fluids, sexual contact, perinatal
  • Incubation period: 30–180 d
  • Subclinical in 70%
  • FHF in 1%
  • Risk of chronic hepatitis increased with age at infection and comorbidities:
    • Neonatal: >90%
    • Infant: 50%
    • Child: 20%
    • Immunocompetent adult: 1–5%
    • Immunocompromised adult: 50%
  • Risk of cirrhosis, hepatocellular carcinoma
• Hepatitis C (HCV):
  • Transmission: Blood >> sexual and perinatal
  • Incubation period:15–160 d
  • FHF rare
  • 80% progress to chronic disease
  • Risk of cirrhosis, hepatocellular carcinoma
• Hepatitis D (HDV):
  • HDV can be transmitted only in the presence of HBV infection:
    • 2 patterns of infection: Simultaneous infection with HBV and HDV or HDV superinfection in an individual with chronic HBV
  • Same transmission as HBV
  • Incubation period: 30–180 d
  • FHF in 3%
  • 5% progress to chronic disease
  • Risk of cirrhosis 3 times higher in HDV-infected individual compared with HBV infection alone
• Hepatitis E (HEV):
  • Most common cause of acute hepatitis and jaundice worldwide
  • Rarely found outside developing countries
  • Typically seen as outbreaks
  • Transmission: Fecal–oral, waterborne, foodborne
  • Incubation period: 14–60 d
  • FHF in 1–2% of previously healthy adults, 10–20% in pregnant patients
  • Chronic infection almost exclusively in immunocompromised persons
• Alcoholic hepatitis:
  • Associated with >14 drinks/wk in women and >21 drinks/wk in men
  • Sequelae of chronic use:
    • Hepatic steatosis in 90–100%
    • Hepatitis in 10–35%
    • Cirrhosis in 5–15%
  • Increased association with chronic viral hepatitis
  • Maddrey discriminant function (MDF) ≥32 associated with only 50–65% survival
    • MDF = 4.6 × [prolongation of PT above control(s)] + serum bilirubin(mg/dL)
  • Abscess-induced hepatitis:
    • Entamoeba histolytica, pyogenic
• Secondary hepatitis viruses:
  • CMV, EBV, HSV, HIV
• Medication and toxin induced:
  • Acetaminophen toxicity is the most common cause of acute liver failure in the western world
  • Dose-dependent (e.g., acetaminophen)
  • Idiosyncratic (e.g., isoniazid)
• Autoimmune hepatitis:
  • Cell-mediated immunologic attack on hepatocytes
  • May be associated with a personal or family history of autoimmune disease
  • Tends to affect young to middle-aged women
• Nonalcoholic fatty liver disease:
  • Most common form of chronic liver disease in the U.S., affecting 25% of adults
  • Associated with steatohepatitis and rarely cirrhosis
• Inherited liver disease:
  • Wilson disease
  • Hemochromatosis
  • α-1 antitrypsin deficiency

• Vast majority of cases are caused by HAV
• Perinatal HBV infection develops into chronic disease 90% of the time

• 20% case fatality for HEV during pregnancy
• Acute fatty liver of pregnancy (AFLP):
  • May progress to DIC
• Hemolysis, Elevated Liver enzymes, and Low Platelets (HELLP) syndrome
• Immunoprophylaxis is safe during pregnancy