A 25-year-old blood donor has jaundice with dark urine. His HBsAg is negative and anti-HBc IgM is strongly positive. This serological profile indicates:
- A Resolved hepatitis B infection
- B Vaccination-induced immunity
- C The window period of acute hepatitis B ✓
- D Chronic inactive carrier state
Correct answer: C. The window period of acute hepatitis B
Explanation
In the window period of acute hepatitis C, HBsAg has fallen below detectable levels but anti-HBs has not yet appeared, leaving anti-HBc IgM as the only marker of active infection and the diagnostic clue here. Resolved infection shows positive anti-HBs together with anti-HBc IgG, vaccination gives anti-HBs alone without core antibody, and a chronic carrier would have persistent HBsAg positivity, all incompatible with this profile.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.