Hematology

Mentzer Index

Differentiates Iron Deficiency Anemia from Beta-Thalassemia Trait.

Parameters

fL
×10⁶/µL (Millions)

Mentzer Index Result

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FormulaMentzer Index = MCV [fL] / RBC Count [Millions/µL]

Clinical Pearls

Patients with Thalassemia trait typically have a high RBC count relative to the degree of microcytosis (thus a low ratio). In iron deficiency, the marrow cannot produce RBCs effectively, leading to a low RBC count (thus a higher ratio).

Limitations

It is a screening tool, not diagnostic. It should not replace definitive testing such as iron studies (ferritin, transferrin saturation) or Hemoglobin electrophoresis.