🩸 Mentzer Index Calculator
Use the Mentzer index to distinguish iron deficiency from thalassaemia trait in microcytosis.
Mentzer Index Calculator
MCV (fL)
RBC count (×10¹²/L)
When to use
First-pass discrimination of microcytic anaemia.
How it works
Mentzer index = MCV ÷ RBC count. < 13 favours thalassaemia trait; > 13 favours iron deficiency.
Key points
- Thalassaemia trait: high RBC, low MCV → low index.
- Iron deficiency: low RBC → high index.
- Confirm with ferritin and haemoglobin electrophoresis.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.