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Mentzer Index

MCV divided by red cell count, to help separate thalassaemia trait from iron deficiency in microcytosis.

For healthcare professionalsHematologyv1.0.1

For healthcare professionals / clinical use. Not a self-diagnosis tool.

Your measurements

fL
×10¹²/L

Calculated on your device. Nothing is sent to a server.

Your result will appear here

Enter your measurements, then press Calculate.

Methodology

Mentzer (1973)

MI = MCV (fL) ÷ RBC (×10¹²/L); < 13 favours thalassaemia trait, > 13 iron deficiency

A screening index only; confirmation needs iron studies and haemoglobin electrophoresis or HPLC.

Who it is for
Microcytic anaemia (low MCV).
Version
1.0.1

How this calculator works

Where the formula comes from

  • Mentzer proposed the index in a 1973 Lancet letter to separate iron deficiency from thalassaemia trait: MCV (fL) ÷ red cell count (×10¹²/L), below 13 favouring thalassaemia trait and above 13 iron deficiency.[1]

Versions and alternatives

  • More than 40 discriminant indices have been proposed; a 2015 meta-analysis of 12 of them found none fully sensitive and specific, and all performed better in adults than in children.[2]

Where accuracy falls (published evidence)

  • In 434 Saudi children with microcytosis, the index had 74% sensitivity and 63% specificity for beta-thalassaemia trait, and the authors judged it not highly reliable.[3]
  • In 347 Pakistani children aged 1–5 years, using ferritin as reference, it had 80.7% sensitivity and 77.7% specificity for iron deficiency anaemia.[4]

Sources

  1. Mentzer WC Jr. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973;1(7808):882. doi:10.1016/S0140-6736(73)91446-3
  2. Hoffmann JJ, Urrechaga E, Aguirre U. Discriminant indices for distinguishing thalassemia and iron deficiency in patients with microcytic anemia: a meta-analysis. Clin Chem Lab Med. 2015;53(12):1883–1894. doi:10.1515/cclm-2015-0179
  3. Althumairi A, AlQarni AM, Alkaltham NK, et al. Diagnostic test performance of the Mentzer index in evaluating Saudi children with microcytosis. Front Med (Lausanne). 2024;11:1361805. doi:10.3389/fmed.2024.1361805
  4. Sherali A, Ahad A, Tikmani SS, Sohail S. Screening of iron deficiency anemia in children using Mentzer index in Pakistan: a cross sectional study. Glob Pediatr Health. 2023;10:2333794X221130986. doi:10.1177/2333794X221130986

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on

Worked example: how to calculate mentzer index

Inputs

Mean corpuscular volume (MCV)
65 fL
Red blood cell count
6 ×10¹²/L

Result

Mentzer index
10.8

Under 13: pattern favouring thalassaemia trait

Calculation:

65/6 = 10.83

An illustration with sample values, worked out with the same method the tool above uses.

Limitations

  • Discriminant indices are not fully sensitive and specific, and their performance is generally poorer in children than in adults (Hoffmann 2015).

References

  1. Mentzer WC Jr. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973;1(7808):882. doi:10.1016/S0140-6736(73)91446-3
  2. Hoffmann JJ, Urrechaga E, Aguirre U. Discriminant indices for distinguishing thalassemia and iron deficiency in patients with microcytic anemia: a meta-analysis. Clin Chem Lab Med. 2015;53(12):1883–1894. doi:10.1515/cclm-2015-0179

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