Elevated Red Blood Cell Indices: Clinical Significance and Diagnostic Approach

Introduction to Red Blood Cell Indices

The American Gastroenterological Association notes that MCH (Mean Corpuscular Hemoglobin) measures the average amount of hemoglobin per red blood cell, and MCV (Mean Corpuscular Volume) measures the average size of red blood cells 2

The American College of Physicians suggests that true polycythemia can present with elevated red cell indices, often accompanied by elevated hemoglobin/hematocrit and other clinical features 1
Clonal proliferation of erythroid precursors leads to larger cells with increased hemoglobin content, according to the Mayo Clinic 1

Certain medications can cause macrocytosis with elevated red cell indices, including anticonvulsants, methotrexate, and other chemotherapeutic agents, as noted by the National Institute of Health 3
Chronic alcohol use can cause macrocytosis independent of nutritional deficiencies, with elevated MCV and sometimes elevated MCH/MCHC 3

The European Hematology Association recommends assessing for iron status by checking serum ferritin, transferrin saturation, and iron studies 2, 4
The American Society of Hematology suggests evaluating vitamin status by confirming B12 and folate levels, and considering homocysteine and methylmalonic acid levels for functional deficiencies 3
Bone marrow examination may be necessary in cases where the cause remains unclear, according to the International Society of Nephrology 4, 5

Elevated MCH, MCV, and MCHC may precede the development of overt disease, and can help distinguish between different types of anemia and polycythemia, as noted by the American College of Physicians 1, 2
Serial monitoring of these indices can help assess response to treatment in conditions like hemochromatosis, according to the National Institute of Diabetes and Digestive and Kidney Diseases 4, 5
Concurrent conditions may mask expected changes in red cell indices, as suggested by the European Hematology Association 6