Gastroenterology · Viral Hepatitis
The facts most likely to be tested
HBsAg is the first serologic marker to appear in acute infection and indicates active viral replication.
Anti-HBs is the only marker that indicates immunity, either through natural recovery or vaccination.
HBeAg is a marker of high infectivity and active viral replication, correlating with high levels of HBV DNA.
Anti-HBc IgM is the diagnostic hallmark of acute hepatitis B infection and is the only positive marker during the window period.
Chronic hepatitis B is defined by the persistence of HBsAg for greater than six months.
Polyarteritis nodosa is the classic extrahepatic manifestation associated with chronic hepatitis B infection.
Tenofovir or entecavir are the preferred first-line antiviral therapies for patients with chronic hepatitis B requiring treatment.
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A 32-year-old male presents with jaundice, right upper quadrant pain, and dark urine for one week. He reports unprotected sexual intercourse with a new partner three months ago. Laboratory studies reveal elevated ALT/AST in the 1000s, positive HBsAg, positive anti-HBc IgM, and negative anti-HBs. His HBeAg is positive, indicating high viral load.
Which serologic profile would be expected in this patient if he were in the 'window period'?
Isolated anti-HBc IgM
The window period occurs after HBsAg disappears but before anti-HBs appears, leaving anti-HBc IgM as the only detectable marker of recent acute infection.
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Etiology / Epidemiology
Transmitted via parenteral, sexual, or vertical routes. High-risk groups include IV drug users, healthcare workers, and multiple sexual partners.
Clinical Manifestations
Acute phase presents with icterus and RUQ pain. Chronic phase is often asymptomatic until cirrhosis or hepatocellular carcinoma develops.
Diagnosis
The HBsAg is the first marker to appear. HBV DNA viral load is the gold standard for monitoring treatment response.
Treatment
Tenofovir or Entecavir are first-line for chronic infection. Do not use interferon in decompensated cirrhosis.
Prognosis
Risk of hepatocellular carcinoma persists even without cirrhosis. Monitor AFP and ultrasound every 6 months in high-risk patients.
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Epidemiology & Etiology
Hepatitis B is a hepadnavirus transmitted through blood and body fluids. Vertical transmission is the most common cause of chronic infection worldwide. Unvaccinated individuals and those in endemic regions are at highest risk.
Pertinent Anatomy
The virus targets hepatocytes. Chronic inflammation leads to periportal fibrosis and eventual bridging fibrosis, disrupting hepatic architecture.
Pathophysiology
The virus is not directly cytopathic; liver damage is mediated by the host immune response (CD8+ T-cells). Persistent infection leads to continuous cycles of necrosis and regeneration, increasing the risk of somatic mutations and malignancy.
Clinical Manifestations
Acute infection may present with serum sickness-like symptoms, including polyarteritis nodosa and urticaria. Patients often report dark urine and acholic stools. Watch for signs of fulminant hepatic failure: encephalopathy and coagulopathy.
Diagnosis
The HBsAg indicates active infection. Anti-HBs indicates immunity (vaccination or recovery). HBeAg signifies high infectivity and active viral replication. HBV DNA is the definitive test for viral load.
Treatment
Acute infection is supportive. Chronic infection requires Tenofovir or Entecavir to suppress viral replication. Interferon-alpha is contraindicated in pregnancy and decompensated liver disease due to severe side effects.
Prognosis
Chronic carriers have a 100-fold increased risk of hepatocellular carcinoma. Patients must undergo AFP screening and abdominal imaging every 6 months if they meet criteria for cirrhosis or high-risk status.
Differential Diagnosis
Hepatitis A: fecal-oral transmission, no chronic state
Hepatitis C: high rate of chronicity, usually asymptomatic
Autoimmune Hepatitis: elevated ANA and anti-smooth muscle antibodies
Alcoholic Hepatitis: AST:ALT ratio > 2:1
Wilson Disease: low ceruloplasmin and Kayser-Fleischer rings