Mentzer index
Separates beta-thalassaemia trait from iron deficiency anaemia in microcytic hypochromic anaemia.
When to use
Microcytic hypochromic anaemia where a first step between thalassaemia trait and iron deficiency is wanted.
Pearls and pitfalls
- The index is MCV divided by the red cell count, with no other unit.
- Below 13 favours beta-thalassaemia trait; 13 or more favours iron deficiency anaemia.
- The result is a hint, not a diagnosis: confirm with haemoglobin electrophoresis or the iron panel.
- The red cell count enters in millions per microlitre, as on the blood count.
Fill in the fields to see the result.
Formula
Mentzer index = MCV (fL) divided by the red blood cell count (millions/µL).
Evidence
Index proposed to differentiate iron deficiency from thalassaemia trait, compared in microcytic anaemia cohorts with haemoglobin electrophoresis as the reference.
References
- Mentzer WC. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973;301(7808):882. doi:10.1016/S0140-6736(73)91446-3
- Patra S, Shome A, Patra CC, Mahto SK. Patra index and Mentzer index: a retrospective comparative study to differentiate beta-thalassemia trait from iron deficiency anemia. J Family Med Prim Care. 2025;14:4568. doi:10.4103/jfmpc.jfmpc_2075_24
Frequently asked questions
What is Mentzer index?
Separates beta-thalassaemia trait from iron deficiency anaemia in microcytic hypochromic anaemia. Microcytic hypochromic anaemia where a first step between thalassaemia trait and iron deficiency is wanted.
How is the result calculated?
Mentzer index = MCV (fL) divided by the red blood cell count (millions/µL).
How should the result be interpreted?
Index proposed to differentiate iron deficiency from thalassaemia trait, compared in microcytic anaemia cohorts with haemoglobin electrophoresis as the reference.
What are the sources?
Mentzer WC. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973;301(7808):882. Patra S, Shome A, Patra CC, Mahto SK. Patra index and Mentzer index: a retrospective comparative study to differentiate beta-thalassemia trait from iron deficiency anemia. J Family Med Prim Care. 2025;14:4568.