Haematology: beta-thalassaemia trait: 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 · Haematology: beta-thalassaemia trait

Sample item

A 24-year-old woman has mild fatigue. Haemoglobin is 10.2 g/dL, MCV 62 fL, red cell count 5.6 million per microlitre, RDW normal and serum ferritin 90 ng/mL. The smear shows microcytic hypochromic cells with target cells. Which test best confirms the diagnosis?

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

The answer and the reasoning

D. Haemoglobin HPLC showing raised HbA2

Mentzer index is MCV divided by red cell count: 62 / 5.6 is about 11, below 13, which favours thalassaemia over iron deficiency. A normal ferritin and normal RDW support this. Beta-thalassaemia trait is confirmed by HPLC or electrophoresis showing HbA2 above 3.5%, and screening matters in India because of high carrier rates.

Option by option

  • A. Bone marrow iron stain

    A marrow iron stain is invasive and unnecessary when ferritin is normal.

  • B. Direct Coombs test

    A Coombs test detects antibody-mediated haemolysis, which is not suggested by microcytosis with a high red cell count.

  • C. Serum vitamin B12 level

    Vitamin B12 deficiency produces macrocytosis, not microcytosis.

  • D. Haemoglobin HPLC showing raised HbA2 (correct)

    Correct. A raised HbA2 is the hallmark of beta-thalassaemia trait.

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 D, Haemoglobin HPLC showing raised HbA2. Mentzer index is MCV divided by red cell count: 62 / 5.

Why is "Bone marrow iron stain" not the answer?

A marrow iron stain is invasive and unnecessary when ferritin is normal.

Why is "Direct Coombs test" not the answer?

A Coombs test detects antibody-mediated haemolysis, which is not suggested by microcytosis with a high red cell count.

Why is "Serum vitamin B12 level" not the answer?

Vitamin B12 deficiency produces macrocytosis, not microcytosis.

What concept does this question test?

It tests Haematology: beta-thalassaemia trait in General Medicine. 6 is about 11, below 13, which favours thalassaemia over iron deficiency. A normal ferritin and normal RDW support this. Beta-thalassaemia trait is confirmed by HPLC or electrophoresis showing HbA2 above 3.5%, and screening matters in India because of high carrier rates.

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 Haematology: beta-thalassaemia trait?

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.