🩸 Mentzer Index Calculator
Use the Mentzer index to distinguish iron deficiency from thalassaemia trait in microcytosis.
Clinical takeaway
Thalassaemia trait: high RBC, low MCV → low index.
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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.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| MCV | 70 fL |
|---|---|
| RBC count | 6.0 ×10¹²/L |
→Mentzer index11.7
- Interpretation：< 13 — favours thalassaemia trait
- Formula：MCV ÷ RBC (RBC in ×10¹²/L)
Frequently asked questions
- What is Mentzer Index Calculator?
- Use the Mentzer index to distinguish iron deficiency from thalassaemia trait in microcytosis.
- How is Mentzer Index Calculator calculated? What is the core formula?
- Mentzer index = MCV ÷ RBC count. < 13 favours thalassaemia trait; > 13 favours iron deficiency.
- When is Mentzer Index Calculator used?
- First-pass discrimination of microcytic anaemia.
- What are the key clinical points for Mentzer Index Calculator?
- Thalassaemia trait: high RBC, low MCV → low index. Iron deficiency: low RBC → high index. Confirm with ferritin and haemoglobin electrophoresis.
- What are the limits and cautions when using Mentzer Index Calculator?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Mentzer Index Calculator calculated in practice? Can you show a worked example?
- Inputs: MCV 70 fL, RBC count 6.0 ×10¹²/L → Result: Mentzer index 11.7（Interpretation: < 13 — favours thalassaemia trait, Formula: MCV ÷ RBC (RBC in ×10¹²/L)）