Erythrocyte indices

Also commonly called red blood cell indices or RBC indices, the erythrocyte indices are a set of clinically useful parameters calculated from measurements of erythrocytes. These are commonly reported as part of a complete blood count.

Basic indices

Mean corpuscular volume

Usually called MCV, this is the average volume enclosed by a red cell, calculated as:

 MCV = 10 x (Hematocrit / Red Blood Cell Count)

It is especially useful in the differential diagnosis of anemia. The basic classification of MCV, using approximate values, is:

• <80: Microcytic
• 80-100: Normocytic
• >100: Macrocytic

Exact cutoffs for each range vary with the patient's age and sex, and both laboratory method and expert opinion. For example, a number of hematologists use < 78 as the beginning of the microcytic range.

Additional derivations

Mentzer index

Mentzer Index = MCV / RBC Count

• Ratio <13: Thalassemia
• Ratio >13: Iron deficiency anemia, Hemoglobinopathy