A 28-year-old woman comes to the emergency department for a 1-week history of jaundice and nausea. She recalls eating some seafood last weekend at a cookout. She lives at home with her 2-year-old son who attends a daycare center. The child's immunizations are up-to-date, and his last hepatitis A vaccine was administered 6 weeks ago. The woman's temperature is 37.5°C (99.5°F), pulse is 82/min, and blood pressure is 134/84 mm Hg. Examination shows scleral icterus. The liver is palpated 2-cm below the right costal margin and is tender. Her serum studies show: Total bilirubin 3.4 mg/dL Alkaline phosphatase 89 U/L AST 185 U/L ALT 723 U/L Hepatitis A IgM antibody positive Hepatitis B surface antibody positive Hepatitis B surface antigen negative Hepatitis B core IgM antibody negative Hepatitis C antibody negative Which of the following health maintenance recommendations is most appropriate for the child at this time?

Administer hepatitis B immunoglobulin and hepatitis B vaccine

Administer hepatitis B immunoglobulin only

Administer hepatitis A vaccine and hepatitis A immunoglobulin

A 28-year-old man presents to the office with complaints of malaise, anorexia, and vomiting for the past 2 weeks. He also says that his urine is dark. The past medical history is unremarkable. The temperature is 36.8°C (98.2°F), the pulse is 72/min, the blood pressure is 118/63 mm Hg, and the respiratory rate is 15/min. The physical examination reveals a slightly enlarged, tender liver. No edema or spider angiomata are noted. Laboratory testing showed the following: HBsAg Positive IgM anti-HBc < 1:1,000 Anti-HBs Negative HBeAg Positive Anti-HBe Negative HBV DNA 2.65 × 10⁹ IU/L Alpha-fetoprotein 125 ng/mL What is the most likely cause of this patient's condition?

Acute exacerbation of chronic HBV infection

Resolved HBV infection (innate immunity)

A 35-year-old man with no known past medical history presents to his physician because he is applying for a job as a healthcare worker, which requires screening for the hepatitis B virus (HBV). The patient states that he is in good health and denies any symptoms. His vital signs and physical exam are unremarkable. Labs are drawn, and the patient's HBV serology shows the following: HBsAg: positive anti-HBsAg antibody: negative anti-HBcAg IgM: negative anti-HBcAg IgG: positive HBeAg: negative anti-HBeAg antibody: positive Which of the following best describes this patient's results?

Chronically infected, low infectivity

Immune due to previous infection

Immune due to previous vaccination

Chronically infected, high infectivity

A 44-year-old woman presents to the emergency department with jaundice and diffuse abdominal pain. She denies any previous medical problems and says she does not take any medications, drugs, or supplements. Her temperature is 97.6°F (36.4°C), blood pressure is 133/87 mmHg, pulse is 86/min, respirations are 22/min, and oxygen saturation is 100% on room air. Physical exam is notable for sclera which are icteric and there is tenderness to palpation over the right upper quadrant. Laboratory studies are ordered as seen below. Hepatitis B surface antigen: Positive Hepatitis B surface antibody: Negative Hepatitis B core antibody IgM: Negative Hepatitis B core antibody IgG: Positive Hepatitis B E antigen: Positive Hepatitis B E antibody (anti-HBe): Negative Which of the following is the most likely diagnosis?

No hepatitis B vaccination or infection

A 38-year-old woman comes to the physician because of a 3-month history of moderate abdominal pain that is unresponsive to medication. She has a history of two spontaneous abortions at 11 and 12 weeks' gestation. Ultrasound examination of the abdomen shows normal liver parenchyma, a dilated portal vein, and splenic enlargement. Upper endoscopy shows dilated submucosal veins in the lower esophagus. Further evaluation of this patient is most likely to show which of the following findings?

Increased serum bilirubin levels

Viral hepatitis (A, B, C, D, E) for USMLE Step 2 CK: High-Yield Internal Medicine Lessons

Viral Hepatitis - The Usual Suspects

Transmission: 📌 Mnemonic: "Vowels are bowels." Hep A & E are fecal-oral. Hep B, C, D are via blood/body fluids.
Virus Type: All are RNA viruses except for Hepatitis B, a DNA virus.

Virus	Family	Transmission	Chronic Risk	Key Features
A	Picornavirus	Fecal-Oral	No	Acute, self-limiting; often asymptomatic in children.
B	Hepadnavirus	Parenteral, Sexual	Yes	DNA virus; "ground-glass" hepatocytes; risk of HCC.
C	Flavivirus	Parenteral (IVDU)	>85%	High chronic rate; cryoglobulinemia; leading cause of cirrhosis/HCC.
D	Deltavirus	Needs HBV	Yes	Defective virus; superinfection (worse) vs. co-infection.
E	Hepevirus	Fecal-Oral	No	Zoonotic; high mortality in pregnant women.

⭐ More than 85% of individuals infected with Hepatitis C virus (HCV) will develop chronic infection, a major risk factor for cirrhosis and hepatocellular carcinoma.

Hepatitis B Serology - Marker Mayhem

HBsAg (Surface Antigen): First marker to appear. If positive > 6 months → Chronic.
Anti-HBs (Surface Antibody): Indicates immunity from vaccination or recovery.
Anti-HBc (Core Antibody):
- IgM: Marker of acute infection or acute flare of chronic infection. Key marker for the "window period."
- IgG: Marker of past or chronic infection.
HBeAg (e Antigen): Indicates active viral replication and high infectivity.
Anti-HBe (e Antibody): Indicates low viral replication and lower infectivity.

⭐ Window Period: Time when HBsAg has disappeared but Anti-HBs is not yet detectable. Anti-HBc IgM is the sole positive marker of infection.

Hepatitis B Serological Markers Timeline

HCV & HDV - Chronic Co-conspirators

Hepatitis C (HCV)
- Single-stranded RNA Flavivirus; transmitted via IVDU, blood products (pre-1992), sexual contact.
- Leads to chronic infection in >75% of cases, often asymptomatic until cirrhosis develops.
- Diagnosis: Anti-HCV antibodies (screen), confirmed by HCV RNA (active infection).
- Treatment: Direct-acting antivirals (DAAs) provide >95% cure rate.
Hepatitis D (HDV)
- Defective RNA virus requiring HBsAg for replication.
- Coinfection: Simultaneous HBV & HDV infection.
- Superinfection: HDV infection in a chronic HBV carrier; more severe, higher risk of cirrhosis.

⭐ High-Yield: Mixed cryoglobulinemia (palpable purpura, arthralgias, glomerulonephritis) is a classic extrahepatic manifestation of chronic HCV.

HDV-HBV Coinfection vs. Superinfection Profiles

Path & Presentation - When the Liver Cries

Acute: Prodrome (fever, malaise, anorexia) → Icteric phase (jaundice, dark urine, pale stool, RUQ pain).
Chronic (HBV, HCV): Often asymptomatic for years, leading to fatigue, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC).
Labs: ↑↑ ALT & AST (viral hepatitis hallmark), ↑ Bilirubin, ↑ PT.

⭐ A serum sickness-like syndrome (fever, rash, arthralgias) can be an extrahepatic manifestation of acute HBV infection.

High‑Yield Points - ⚡ Biggest Takeaways

Hepatitis A & E are transmitted fecal-orally, causing only acute hepatitis.

Hepatitis B, C, & D are bloodborne and can cause chronic infection, leading to cirrhosis and hepatocellular carcinoma (HCC).

Hepatitis B is a DNA virus; its serology is crucial for diagnosis and staging.

Hepatitis C has a high rate of chronicity; treat with Direct-Acting Antivirals (DAAs).

Hepatitis D requires HBsAg for replication.

Hepatitis E is associated with high mortality in pregnant women.

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