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MBBS QUESTION #10223
Question 1
A patient has microcytic hypochromic anemia. The Mentzer index (MCV divided by RBC count) is calculated and found to be low (below 13), with an RBC count that is high relative to the degree of anemia. This pattern favors which diagnosis over the alternative?
  • Iron deficiency anemia
  • Beta-thalassemia trait✔️
  • Megaloblastic anemia
  • Anemia of chronic disease
Correct Answer Explanation
In thalassemia trait, the bone marrow compensates for smaller, less hemoglobinized red cells by producing a near-normal or even elevated RBC count, giving a low Mentzer index (<13). In iron deficiency anemia, RBC count falls proportionately with hemoglobin, giving a higher index (>13) — a simple bedside tool to prioritize further workup (iron studies vs. hemoglobin electrophoresis).