Hepatitis

Basics

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

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


Pregnancy Considerations
  • 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

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