What does it mean to have an MCH (Mean Corpuscular Hemoglobin) of 26.1 and an MCHC (Mean Corpuscular Hemoglobin Concentration) of 20.6?

Interpretation of MCH 26.1 and MCHC 20.6

An MCH of 26.1 pg and MCHC of 20.6 g/dL strongly suggests iron deficiency anemia, with the MCHC value being abnormally low and requiring further investigation to confirm the diagnosis and rule out potential laboratory error. 1, 2

Understanding These Values

MCH (Mean Corpuscular Hemoglobin) and MCHC (Mean Corpuscular Hemoglobin Concentration) are important red blood cell indices:

• MCH (26.1 pg): This value is slightly below the normal range (typically 27-33 pg) and indicates reduced hemoglobin content per red blood cell (hypochromia).

• MCHC (20.6 g/dL): This value is significantly below the normal range (typically 32-36 g/dL) and represents an unusually low concentration of hemoglobin within red blood cells. A value this low is concerning and may indicate:

  • Severe iron deficiency
  • Possible laboratory error or specimen interference 3

Diagnostic Implications

1. Primary Consideration - Iron Deficiency Anemia:

   • The British Society of Gastroenterology guidelines indicate that reduced MCH is a reliable marker of iron deficiency, potentially more sensitive than MCV 1
   • MCH is particularly useful as it is less dependent on storage and counting machine used 1

2. Possible Laboratory Error:

   • The MCHC value of 20.6 is extremely low and may represent a false reading
   • Potential interferences include cold agglutination, lipid blood interference, or other pre-analytical errors 3

3. Other Differential Diagnoses:

   • Thalassemia trait (though typically MCHC would be normal or only slightly reduced) 2, 4
   • Anemia of chronic disease (though typically with less severe MCHC reduction) 2

Recommended Next Steps

1. Confirm Iron Status:

   • Order serum ferritin (most specific test for iron deficiency) 1, 2
   • Check transferrin saturation (TSAT) - should be low in iron deficiency 1, 2
   • Consider repeat CBC to verify the extremely low MCHC value 3

2. Additional Testing:

   • Complete blood count with hemoglobin measurement
   • Peripheral blood smear to assess red cell morphology
   • If microcytosis is confirmed, consider hemoglobin electrophoresis to rule out thalassemia 2

3. Clinical Correlation:

   • Assess for symptoms of anemia (fatigue, weakness, pallor)
   • Evaluate for potential causes of iron deficiency:
     • Occult blood loss (especially in men and postmenopausal women)
     • Malabsorption disorders
     • Dietary insufficiency
     • Increased iron requirements (pregnancy, adolescence)

Treatment Approach

If iron deficiency is confirmed:

1. Oral Iron Supplementation:

   • Ferrous sulfate 325 mg daily or on alternate days 2
   • Continue for 3 months after hemoglobin normalizes to replenish iron stores

2. Monitoring:

   • Check hemoglobin after 4 weeks of therapy (expect increase of 1-2 g/dL if responding)
   • Monitor ferritin and transferrin saturation monthly during initial treatment

3. Consider IV Iron if no significant improvement after 4-6 weeks of oral therapy 1, 2

Important Caveats

• The extremely low MCHC value (20.6) warrants verification before making definitive conclusions 3
• Normal MCH and MCHC values do not exclude iron deficiency, as demonstrated in studies showing only moderate diagnostic accuracy of these parameters 5
• Investigation of the underlying cause of iron deficiency is crucial, especially in men and postmenopausal women, to avoid missing serious conditions like gastrointestinal malignancy 2