MCV divided by the RBC count.
Helpful in differentiating iron deficiency anemia from beta thalassemia
Quotient of the mean corpuscular volume (MCV, in fL) divided by the red blood cell count (RBC, in Millions per microLiter)Mentzer index
Less than 13 Suggests thalassemia more likely
Greater than 13 Suggests iron-deficiency anemia more likely
Principle of Mentzer index
Marrow cannot produce as many RBCs
RBC count and the MCV will both be low, and as a result, the index will be greater than 13.Iron deficiency
Disorder of globin synthesis
Number of RBCs produced is normal
Cells are smaller and more fragile.
RBC count is normal, but the MCV is low,
so the index will be less than 13Thalassemia