This document defines red blood cell indices and explains how they are used to help diagnose anemia. It describes that red blood cell indices are calculated from a complete blood count test and include the mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Each of these indices provides information about the average size, hemoglobin content, and hemoglobin concentration of red blood cells, which can indicate if cells are macrocytic, microcytic, hypochromic, or hyperchromic. Normal ranges for each index are provided.