Mentzer Index Calculator

Helps differentiate between iron deficiency anemia and beta thalassemia from MCV and RBC values.

Below the tool, there is more information on this haematological index and the principles behind its usage.

The Mentzer Index is useful in differentiating the cause of microcytic anaemia where either iron deficiency and beta thalassemia are suspected, in adult and pediatric patients.

Mentzer Index = MCV/RBC


  • MI >13: Iron Deficiency Anemia is more likely
  • MI <13: Beta Thalassemia is more likely

Mean Corpuscular Volume (MCV)
Red Blood Cell Count (RBC)
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Beta Thalassemia Differential Diagnosis

In 1973 William C Mentzer described a facile way to differentiate between mild microcytic anemia due to beta-thalassemia carrier state and microcytic anemia due to iron deficiency, starting from commonly used blood laboratory tests, by dividing the mean corpuscular volume (MCV) to the red blood cell (RBC) count.

Mentzer Index = MCV/RBC

A threshold of 13 was established, where a Mentzer Index >13 indicates a greater likelihood of iron deficiency anemia diagnosis and a Mentzer Index <13 indicates beta thalassemia is more likely.

Whilst a definitive differential diagnosis between the two types of microcytic anemia is based on HbA2 electrophoresis, serum iron levels, and a ferritin calculation, the Mentzer index is an inexpensive and easy way to screen for the patients that have a higher probability of carrying the beta thalassemia trait (β-TT) and who require further follow-up.

Beta thalassemia is caused by a disruption of globin chain synthesis and results in a normal production of red blood cells but an observed mean corpuscular volume that is lower than normal (as erythrocytes are smaller and more fragile), hence why the index has lower values.

Mean corpuscular volume is expressed in femtoliters (fl) where normal adult values range between 80 and 95 fl.

Red blood cell count is expressed in either millions per μL or millions per mm3 of blood volume where normal adult values range between 4.7 and 6.1 mil/μL in men and 4.2 and 5.4 mil/μL in women.

There have been several studies looking into the reliability of various hematological indices for the differential diagnosis of microcytosis and β-TT in the same patient groups, most on adult populations. A study by Vehapoglu et al. on a pediatric population concluded the Mentzer index was the most reliable from those tested, with the highest sensitivity (98.7%), specificity (82.3%), and Youden's index (81%) for detecting β-TT.



Original reference

Mentzer WC Jr. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973 Apr 21; 1(7808):882.

Other references

Vehapoglu A, Ozgurhan G, Demir AD, et al. Hematological indices for differential diagnosis of Beta thalassemia trait and iron deficiency anemia. Anemia. 2014; 2014:576738.

Specialty: Hematology

System: Circulatory

Objective: Diagnosis

Type: Index

Year Of Study: 1973

Article By: Denise Nedea

Published On: March 9, 2022 · 12:00 AM

Last Checked: March 9, 2022

Next Review: March 9, 2027