What is the next step in managing a patient with microcytic anemia and abnormal Complete Blood Count (CBC) results, including low Hemoglobin (Hb), low Mean Corpuscular Hemoglobin (MCH), and low Mean Corpuscular Hemoglobin Concentration (MCHC)?

Management of Microcytic Anemia with Low Hemoglobin, MCH, and MCHC

The next step in managing a patient with microcytic anemia (Hb 11.2 g/dL, MCH 26.4 pg, MCHC 29.7 g/dL) should be iron studies, including serum ferritin, serum iron, total iron binding capacity (TIBC), and transferrin saturation to confirm iron deficiency as the most likely cause. 1, 2

Initial Diagnostic Workup

• Serum ferritin is the most specific test for iron deficiency in the absence of inflammation. A level <15 μg/L indicates absent iron stores, while <30 μg/L generally indicates low body iron stores 1
• In the presence of inflammation, serum ferritin up to 100 μg/L may still be consistent with iron deficiency 1
• Additional iron studies should include serum iron, TIBC, and transferrin saturation (with values <16% suggesting iron deficiency) 1, 3
• Review peripheral blood smear to confirm microcytic, hypochromic red cell morphology and rule out other abnormalities 4, 5

Differential Diagnosis Considerations

• Iron deficiency anemia is the most common cause of microcytic anemia and should be the primary consideration 2, 6
• Other causes to exclude include:
  • Thalassemia trait (consider if iron studies are normal) 1, 3
  • Anemia of chronic disease (typically with low serum iron, low TIBC, normal/elevated ferritin) 4, 5
  • Sideroblastic anemia (rare) 6, 3
  • Lead toxicity (rare, consider with relevant exposure history) 3

Additional Testing Based on Initial Results

• If iron deficiency is confirmed, investigate the underlying cause, as iron deficiency in adults is presumed to be caused by blood loss 3
• For patients with normal iron studies, consider hemoglobin electrophoresis to evaluate for thalassemia trait 1, 3
• If anemia of chronic disease is suspected (low iron, low TIBC, normal/high ferritin), evaluate for underlying inflammatory conditions 1, 4

Treatment Approach

• For confirmed iron deficiency anemia:
  • Start oral iron supplementation (ferrous sulfate 1 tablet two to three times daily) 7, 2
  • Do not crush or chew tablets to maximize absorption 7
  • Consider adding ascorbic acid to improve iron absorption in resistant cases 1
  • Monitor response with repeat CBC after 4-6 weeks of therapy 2
• For patients who fail to respond to oral iron:
  • Consider intravenous iron if there is true malabsorption or intolerance 2
  • Evaluate for ongoing blood loss or other complicating factors 1, 2

Important Clinical Considerations

• The combination of low Hb, low MCH, and low MCHC strongly suggests iron deficiency as the most likely diagnosis 1, 5
• Normal MCV (88.9 fL) with low MCH and MCHC may represent early iron deficiency before microcytosis develops, or a mixed picture 8, 3
• Investigate the underlying cause of iron deficiency, particularly focusing on gastrointestinal sources of blood loss in adults 1, 3
• Consider specialized testing only if initial iron studies are inconclusive or response to therapy is inadequate 1, 4