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Difficulty: MediumInterpreting Laboratory Results

A 34-year-old healthcare worker is evaluated during a routine employee health examination. He has no significant past medical history and takes no medications. He reports feeling well, with no history of fatigue, jaundice, abdominal pain, or recent acute illnesses. Vital signs are within normal limits. Physical examination reveals no hepatosplenomegaly, scleral icterus, or stigmata of chronic liver disease. The results of his laboratory workup are shown below:

TestResultReference Range
Alanine aminotransferase (ALT)22 U/L10 - 40 U/L
Aspartate aminotransferase (AST)20 U/L10 - 40 U/L
Total bilirubin0.8 mg/dL0.1 - 1.2 mg/dL
Hepatitis B surface antigen (HBsAg)PositiveNegative
Hepatitis B surface antibody (Anti-HBs)NegativePositive
Hepatitis B core antibody, IgM (Anti-HBc IgM)NegativeNegative
Hepatitis B core antibody, IgG (Anti-HBc IgG)PositiveNegative
Hepatitis B e antigen (HBeAg)NegativeNegative
Hepatitis B e antibody (Anti-HBe)PositiveNegative
HBV DNA450 IU/mLNot detected

Based on these findings, which of the following is the most accurate diagnostic interpretation?

  1. Inactive chronic hepatitis B infectionAnswer
  2. B
    Resolved past hepatitis B infection
  3. C
    Acute hepatitis B infection in the window period
  4. D
    Chronic active hepatitis B infection
  5. E
    Immunity to hepatitis B secondary to vaccination

Answer

Inactive chronic hepatitis B infection
The correct answer is inactive chronic hepatitis B infection. This patient has positive HBsAg with a positive Anti-HBc IgG and negative Anti-HBc IgM, which establishes a diagnosis of chronic Hepatitis B infection. Furthermore, he is HBeAg-negative and Anti-HBe-positive, which generally correlates with lower viral infectivity. The diagnosis of an inactive chronic carrier state is definitively confirmed by the low viral load (HBV DNA < 2,000 IU/mL) and normal liver transaminases (ALT and AST), indicating an absence of active viral replication and active hepatic inflammation.

Step-by-Step Solution

1
Evaluate the Hepatitis B surface antigen (HBsAg) status.
HBsAg is positive.
Presence of HBsAg indicates an ongoing Hepatitis B infection, ruling out a resolved infection or immunity from vaccination.
2
Differentiate between an acute and a chronic infection.
Anti-HBc IgM is negative, but Anti-HBc IgG is positive.
The absence of IgM and the presence of IgG against the core antigen confirms that the infection is chronic (lasting longer than 6 months).
3
Assess the level of viral replication and hepatic inflammation.
HBeAg is negative, Anti-HBe is positive, HBV DNA is low (450 IU/mL), and transaminases (ALT/AST) are within normal limits.
This specific combination indicates an inactive carrier state with minimal viral replication and no active liver damage, differentiating it from chronic active hepatitis.

Key Concept

Interpretation of Hepatitis B serological profiles to classify disease state (e.g., active vs. inactive chronic infection).
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Interpreting Laboratory Results

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