A complete blood count shows: hemoglobin 12 g/dL, RBC count 4.0 × 10⁶/µL. Calculate the mean corpuscular hemoglobin (MCH) and interpret the red cell indices.
- A 24 pg; microcytic hypochromic
- B 30 pg; normocytic normochromic ✓
- C 34 pg; macrocytic
- D 40 pg; hyperchromic
Correct answer: B. 30 pg; normocytic normochromic
Explanation
MCH = Hemoglobin (g/dL) × 10 / RBC count (million/µL) = 12 × 10 / 4.0 = 30 pg. Normal MCH is 27 to 33 pg. A value of 30 pg falls within the normocytic normochromic range. MCH <27 pg suggests microcytic hypochromic, and >33 pg suggests macrocytic. 'Hyperchromic' is a misnomer as MCH concentration cannot exceed normal hemoglobin packing.
Reference: Williams Hematology, 10th ed.
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