Infectious diseases: acute hepatitis B serology: practice question

A General Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Medicine · Infectious diseases: acute hepatitis B serology

Sample item

A 26-year-old man has jaundice and ALT of 1800 U/L. Serology shows HBsAg negative, anti-HBs negative, IgM anti-HBc positive and anti-HBc total positive. How should this be interpreted?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Acute hepatitis B in the window period

In acute hepatitis B, HBsAg falls and disappears before anti-HBs appears, leaving a window of weeks when neither is detectable. IgM anti-HBc is the only marker of acute infection during this period. Chronic infection shows persistent HBsAg with IgG anti-HBc, resolved infection shows anti-HBs with anti-HBc, and vaccination shows anti-HBs alone.

Option by option

  • A. Vaccine-induced immunity

    Vaccination produces only anti-HBs and would not cause hepatitis with IgM anti-HBc.

  • B. Acute hepatitis B in the window period (correct)

    IgM anti-HBc positivity with negative HBsAg and anti-HBs identifies the window period of acute infection.

  • C. Past resolved infection with immunity

    Resolved infection would show anti-HBs and IgG anti-HBc, not IgM anti-HBc.

  • D. Chronic hepatitis B infection

    Chronic infection requires HBsAg persisting beyond 6 months, with IgG rather than IgM anti-HBc.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Acute hepatitis B in the window period. In acute hepatitis B, HBsAg falls and disappears before anti-HBs appears, leaving a window of weeks when neither is detectable.

Why is "Vaccine-induced immunity" not the answer?

Vaccination produces only anti-HBs and would not cause hepatitis with IgM anti-HBc.

Why is "Past resolved infection with immunity" not the answer?

Resolved infection would show anti-HBs and IgG anti-HBc, not IgM anti-HBc.

Why is "Chronic hepatitis B infection" not the answer?

Chronic infection requires HBsAg persisting beyond 6 months, with IgG rather than IgM anti-HBc.

What concept does this question test?

It tests Infectious diseases: acute hepatitis B serology in General Medicine. IgM anti-HBc is the only marker of acute infection during this period. Chronic infection shows persistent HBsAg with IgG anti-HBc, resolved infection shows anti-HBs with anti-HBc, and vaccination shows anti-HBs alone.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Infectious diseases: acute hepatitis B serology?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.