RBC Indices Calculator: MCV, MCH and MCHC

Red blood cell indices summarize the size of circulating erythrocytes and their hemoglobin content. They are usually reported automatically as part of a complete blood count, but they can also be reconstructed from hemoglobin, hematocrit, and the red blood cell count. The three traditional calculated indices are mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration, abbreviated MCV, MCH, and MCHC. MCV estimates the average volume of one red blood cell. The standard calculation multiplies hematocrit as a percentage by ten and divides by the RBC count in millions per microliter. Results below roughly 80 fL are described as microcytic, values from 80 through 100 fL as normocytic, and values above 100 fL as macrocytic. These ranges are common adult references, but the reporting laboratory's age-specific interval should take priority. MCH estimates the average mass of hemoglobin in each red cell. It equals hemoglobin in g/dL multiplied by ten and divided by the RBC count. MCHC describes the average hemoglobin concentration within the packed red cells and equals hemoglobin multiplied by one hundred, divided by hematocrit. Unlike MCH, MCHC relates hemoglobin to red-cell volume rather than the number of cells. A low MCHC is often called hypochromia, while a markedly high value may warrant attention to spherocytes, dehydration of cells, cold agglutinins, lipemia, hemolysis, or another analytical issue. The indices help organize an anemia evaluation, but they do not establish a cause. Microcytosis may occur with iron deficiency, thalassemia, chronic inflammation, sideroblastic processes, or lead exposure. Macrocytosis can accompany vitamin B12 or folate deficiency, alcohol use, liver disease, hypothyroidism, reticulocytosis, medication effects, or marrow disorders. Normocytic anemia has another broad differential that includes blood loss, kidney disease, inflammation, hemolysis, and marrow disease. Use measurements from the same specimen because mixing values from different dates makes the derived indices unreliable. Small differences from a laboratory report can result from internal unrounded values or instrument-specific methods. Interpretation also requires the absolute hemoglobin, RBC distribution width, reticulocyte count, blood smear, symptoms, history, and other tests selected by a clinician. Seek prompt care for severe weakness, chest pain, fainting, shortness of breath at rest, active bleeding, or another urgent symptom rather than relying on a calculated index.