A 28-year-old blood donor is screened: HBsAg negative, anti-HBs negative, total anti-HBc positive with anti-HBc IgM positive, ALT mildly elevated. How is this serological pattern interpreted?
- A Immunity from past hepatitis B infection
- B Chronic carrier state with low infectivity
- C Window period of acute hepatitis B infection ✓
- D Vaccination-induced immunity
Correct answer: C. Window period of acute hepatitis B infection
Explanation
During the window period of acute hepatitis C, HBsAg has fallen below detectable levels but protective anti-HBs has not yet appeared. IgM anti-HBc is the only marker present and confirms recent infection, which is why it is the diagnostic marker in this phase. Past resolved infection shows IgG anti-HBc together with anti-HBs, a chronic carrier remains HBsAg positive, and vaccinees show anti-HBs alone without anti-HBc.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.