A woman has MCV 62 fL, red cell count 6.1 million per microlitre and a normal ferritin. What is the Mentzer index and the most likely diagnosis?
Answer and explanation
Correct answer: A. About 10, which suggests thalassaemia trait, so haemoglobin electrophoresis is the next test
- Step 1: The Mentzer index is the MCV divided by the red cell count: 62 divided by 6.1 is about 10. Step 2. A value below 13 with a normal ferritin and a high red cell count favours thalassaemia trait over iron deficiency. Answer: About 10: thalassaemia trait, confirmed by haemoglobin electrophoresis. Why not the others: A value above 13 favours iron deficiency, and ferritin would be low. Sideroblastic anaemia is not suggested here. The arithmetic does not give 38.
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