What this calculator does
Mentzer index works out screens a routine blood count for thalassemia trait versus iron-deficiency anemia. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaMentzer index = MCV (fL) / RBC count (millions/µL)
The inputs explained
| Field | What to enter |
|---|---|
| Mean corpuscular volume (MCV) (fL) | A number, measured in fL. Starts at 90. |
| Red blood cell count (million/µL) | A number, measured in million/µL. Starts at 5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with mean corpuscular volume (mcv)
Every other input is held at the calculator’s starting values while mean corpuscular volume (mcv) varies. Select any row to load that scenario into the calculator.
How the answer changes with mean corpuscular volume (mcv)
| Mean corpuscular volume (MCV) (fL) | Mentzer index | Reading | Note |
|---|---|---|---|
| 45 | 9.0 | Below 13: thalassemia trait is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |
| 67.5 | 13.5 | Above 13: iron-deficiency anemia is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |
| 90 | 18.0 | Above 13: iron-deficiency anemia is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |
| 135 | 27.0 | Above 13: iron-deficiency anemia is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |
| 180 | 36.0 | Above 13: iron-deficiency anemia is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |
| 270 | 54.0 | Above 13: iron-deficiency anemia is more probable | A screening pointer only: diagnosis needs iron studies and/or haemoglobin electrophoresis. |