Use this calculator to estimate the likelihood of thalassemia based on MCV and RBC count. The Mentzer index is a ratio of MCV to RBC that can help distinguish thalassemia from iron deficiency anemia. Use this Mentzer index calculator to determine, if anemia is more probably due to iron deficiency or thalassemia. Calculate the Mentzer Index for differentiating between iron deficiency anemia and thalassemia with this Mentzer Index Calculator. Helps in diagnosing anemia. Learn how to use the Mentzer index to distinguish between iron deficiency anemia and thalassemia trait. Enter your MCV and RBC values and get your Mentzer index result, interpretation, and chart.