Mean Corpuscular Hemoglobin (MCH) is the average weight of hemoglobin in an average red blood cell. MCH correlates with the MCV results. This index is of value in diagnosing severely anemic patients.
The MCH is obtained by dividing the hemoglobin by the red cell count. A simple formula can be used to calculate this value:
MCH (pg) = hemoglobin (in g/dL) × 10 / RBC (in 1012/L)
The factor 10 is used to convert the hemoglobin from grams per deciliter to grams per liter.
Example: If the hemoglobin is 15 g/dL and the RBC is 5 × 1012 cells per liter:
MCH (pg) = 15 g/dL × 10 / 5 × 1012/L = 30 pg
The chief source of MCH error is the RBC count, if done manually. However, when the red cell count is determined by electronic cell counters, the MCH is a reliable index.
MCH should always correlate with the MCV and the MCHC.
An increase in the mean corpuscular hemoglobin is seen in macrocytic anemia MCH may be as high as 50 pg, while a decrease is associated with microcytic anemia (20 pg or less in hypochromic microcytic anemias).