Haematology: thalassaemia trait: practice question

A Pathology 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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Pathology · Haematology: thalassaemia trait

Sample item

A 24-year-old woman has haemoglobin 10.5 g/dL, red cell count 5.8 million per microlitre, MCV 62 fL, normal RDW and normal serum ferritin. What is the Mentzer index and the best next investigation?

A21.5, so serum vitamin B12 and folateB10.7, so haemoglobin HPLC or electrophoresisC10.7, so a trial of oral iron for 3 monthsD21.5, so bone marrow iron staining

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

The answer and the reasoning

B. 10.7, so haemoglobin HPLC or electrophoresis

The Mentzer index is MCV divided by red cell count: 62 / 5.8 = 10.7. A value below 13 with a high red cell count and normal RDW favours thalassaemia trait over iron deficiency, in which the index is above 13. Normal ferritin supports this, and haemoglobin HPLC or electrophoresis is the next step, where beta-thalassaemia trait shows a raised HbA2 of about 3.5 to 7 percent.

Option by option

A. 21.5, so serum vitamin B12 and folate
The arithmetic is wrong, and vitamin deficiencies cause macrocytosis, not a microcytic picture.
B. 10.7, so haemoglobin HPLC or electrophoresis (correct)
Correct. The index is 10.7, and HPLC will show raised HbA2 if this is beta-thalassaemia trait.
C. 10.7, so a trial of oral iron for 3 months
The index is correct, but a trial of iron is inappropriate with a normal ferritin and a thalassaemia pattern.
D. 21.5, so bone marrow iron staining
The arithmetic is wrong, since 62 / 5.8 is 10.7 and not 21.5, and marrow iron staining is not needed here.

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.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is B, 10.7, so haemoglobin HPLC or electrophoresis. The Mentzer index is MCV divided by red cell count: 62 / 5.

Why is "21.5, so serum vitamin B12 and folate" not the answer?

The arithmetic is wrong, and vitamin deficiencies cause macrocytosis, not a microcytic picture.

Why is "10.7, so a trial of oral iron for 3 months" not the answer?

The index is correct, but a trial of iron is inappropriate with a normal ferritin and a thalassaemia pattern.

Why is "21.5, so bone marrow iron staining" not the answer?

The arithmetic is wrong, since 62 / 5.8 is 10.7 and not 21.5, and marrow iron staining is not needed here.

What concept does this question test?

It tests Haematology: thalassaemia trait in Pathology. 8 = 10.7. A value below 13 with a high red cell count and normal RDW favours thalassaemia trait over iron deficiency, in which the index is above 13. Normal ferritin supports this, and haemoglobin HPLC or electrophoresis is the next step, where beta-thalassaemia trait shows a raised HbA2 of about 3.5 to 7 percent.

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: thalassaemia trait?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.