Interpretation of Red Blood Cell Indices

Understanding MCH and MCHC Values

• MCH measures the average amount of hemoglobin per red blood cell, while MCHC measures the average concentration of hemoglobin within red blood cells 1
• Normal MCH typically ranges from 27-33 pg and normal MCHC from 32-36 g/dL; values below these ranges suggest hypochromic red cells, commonly seen in iron deficiency 2

Diagnostic Approach

• Complete blood count (CBC) with red cell indices to assess for anemia and characterize the type 2
• Serum ferritin and transferrin saturation (TSAT) to evaluate iron status - these are more reliable markers than MCH/MCHC alone 3
• Reticulocyte count to assess bone marrow response - low count suggests impaired erythropoiesis 2
• C-reactive protein (CRP) to assess for underlying inflammation that may affect interpretation of iron studies 2

Management Recommendations

• For confirmed iron deficiency (serum ferritin <30 μg/L without inflammation or <100 μg/L with inflammation), iron supplementation is indicated 3
• In patients with heart failure and iron deficiency, intravenous iron (particularly ferric carboxymaltose) has shown benefits in improving exercise capacity and quality of life 3
• Follow-up testing of ferritin and TSAT should be performed after 3 months of treatment and then 1-2 times per year 3

Common Pitfalls and Caveats

• Mixed nutritional deficiencies can mask typical findings - concurrent iron and B12/folate deficiencies may present with complex patterns of red cell indices 2
• MCH and MCHC should not be used in isolation to diagnose iron deficiency; they should be interpreted alongside ferritin and transferrin saturation 3
• Mean corpuscular volume (MCV), MCH, and MCHC have been found to be unreliable markers when used alone for iron deficiency status assessment 3