Normal MCH and MCHC Do NOT Rule Out Microcytic Anemia
Normal MCH (26.2) and MCHC (30.4) values do not exclude microcytic anemia, and you must check the MCV and complete iron studies to properly evaluate for iron deficiency. The statement in your question contains a critical error—these values alone cannot diagnose microcytic anemia.
Understanding the Red Cell Indices
MCV is the Primary Determinant of Microcytic Anemia
- Microcytic anemia is defined by a low MCV (<80 fL in adults), not by MCH or MCHC alone 1.
- The British Society of Gastroenterology guidelines emphasize that automated cell counters measure reduced MCH (hypochromia) and reduced MCV (microcytosis) as markers accompanying iron deficiency, but MCV is the defining parameter for microcytosis 1.
- MCH may actually be more sensitive than MCV for detecting iron deficiency and is less dependent on storage conditions and counting machines 1.
Why Your Values Need Context
- MCH of 26.2 pg is actually LOW (normal range typically 27-33 pg), indicating hypochromia, which suggests iron deficiency 1.
- MCHC of 30.4 g/dL is at the lower end of normal (normal range typically 32-36 g/dL), also suggesting possible hypochromia 1.
- However, without the MCV value, you cannot determine if microcytic anemia is present 1.
The Correct Diagnostic Approach
Essential First Steps
Check the MCV immediately—if MCV <80 fL, microcytic anemia is present regardless of MCH/MCHC values 1.
Minimum Workup for Suspected Iron Deficiency
The European consensus on inflammatory bowel disease anemia provides clear guidance that applies broadly 1:
- Complete blood count with MCV, MCH, and RDW 1
- Serum ferritin (most specific test for iron deficiency) 1
- Transferrin saturation 1
- CRP (to assess for inflammation that may falsely elevate ferritin) 1
- Reticulocyte count 1
Interpreting Ferritin Correctly
- Ferritin <15 μg/L is highly specific for iron deficiency (specificity 0.99) 1.
- Ferritin <30 μg/L indicates low iron stores in the absence of inflammation 1.
- Ferritin <45 μg/L provides optimal sensitivity/specificity trade-off in clinical practice (specificity 0.92) 1.
- In the presence of inflammation, ferritin up to 100 μg/L may still indicate iron deficiency because ferritin is an acute phase reactant 1.
Critical Pitfalls to Avoid
Don't Assume Normal MCH/MCHC Rules Out Problems
- Both microcytosis and hypochromia lose sensitivity for iron deficiency in the presence of chronic disease, thalassemia, or vitamin B12/folate deficiency 1.
- Microcytosis and macrocytosis can coexist and neutralize each other, resulting in a falsely normal MCV—check RDW in this situation, as elevated RDW indicates iron deficiency 1.
Consider Alternative Causes of Microcytosis
If iron studies are normal with confirmed microcytosis 1:
- Thalassemia (MCV typically reduced out of proportion to anemia; consider Hb electrophoresis, especially with appropriate ethnic background) 1
- Anemia of chronic disease 1
- Sideroblastic anemia 1
- Lead poisoning (rare) 1
Response to Iron Therapy as Diagnostic Tool
- A hemoglobin rise ≥10 g/L within 2 weeks of iron therapy is highly suggestive of absolute iron deficiency, even if iron studies are equivocal 1.
Bottom Line
Your MCH is actually low and MCHC is borderline low, which suggests possible iron deficiency with hypochromia. You must obtain the MCV to determine if microcytic anemia is present, then proceed with serum ferritin and transferrin saturation to confirm iron deficiency 1. The statement that "normal MCH and MCHC indicate microcytic anemia" is backwards—low values suggest it, but MCV defines it.