How is microcystic iron deficiency anemia treated?

Treatment of Microcytic Iron Deficiency Anemia

First-line treatment for microcytic iron deficiency anemia is oral iron supplementation with ferrous sulfate 200 mg three times daily, which should be continued for 2-3 months after hemoglobin normalizes to replenish iron stores. 1

Diagnosis Confirmation

Before initiating treatment, confirm the diagnosis with:

• Complete blood count showing microcytosis (MCV <80 μm³)
• Iron studies:
  • Serum ferritin <15 μg/L (definitive iron deficiency)
  • Serum ferritin 15-45 μg/L (possible iron deficiency)
  • Transferrin saturation <30% (supports iron deficiency) 1

Treatment Algorithm

First-Line Therapy

• Oral Iron Supplementation:
  • Ferrous sulfate 200 mg three times daily (contains ~65 mg elemental iron per dose)
  • Expected hemoglobin rise of 2 g/dL after 3-4 weeks
  • Continue therapy for 2-3 months after hemoglobin normalizes to replenish stores 1
  • Add ascorbic acid to enhance iron absorption if response is poor 1

Second-Line Therapy (for specific indications)

• Intravenous Iron is indicated for:
  • Intolerance to oral iron
  • Poor absorption
  • Severe anemia (Hb <10 g/dL)
  • Active inflammatory bowel disease 1

IV Iron Administration (Ferric Carboxymaltose):

• For patients ≥50 kg: 750 mg IV in two doses separated by at least 7 days (total 1,500 mg)
• For patients <50 kg: 15 mg/kg IV in two doses separated by at least 7 days
• Alternative single-dose option: 15 mg/kg up to 1,000 mg IV as a single dose 2

Special Considerations

Sideroblastic Anemia

If microcytic anemia is due to sideroblastic anemia (particularly X-linked sideroblastic anemia):

• Initial treatment with pyridoxine 50-200 mg daily
• For responsive patients, maintain with lifelong pyridoxine 10-100 mg daily
• Treat iron overload with phlebotomies 3

Iron Refractory Iron Deficiency Anemia (IRIDA)

For patients with IRIDA:

• Intravenous iron supplementation is required
• Calculate total IV iron dose based on hemoglobin deficit and iron store requirements
• Monitor serum ferritin levels (should not exceed 500 μg/L)
• Administer repeated doses every 3-7 days until total dose is achieved 3

Monitoring Response

• Repeat complete blood count after 4 weeks to assess response
• Continue iron therapy for 2-3 months after normalization of hemoglobin
• Monitor for iron overload during treatment, especially with transfusions or genetic disorders 1

Common Pitfalls and Caveats

1. Failure to identify underlying cause: Always investigate the source of iron deficiency:

   • GI sources of blood loss in men and post-menopausal women
   • Menstrual blood loss in pre-menopausal women
   • Malabsorption conditions (e.g., celiac disease) 1

2. Inadequate duration of therapy: Many practitioners discontinue iron too early, before stores are replenished

3. Misdiagnosis: Ensure other causes of microcytic anemia are ruled out:

   • Thalassemia (consider hemoglobin electrophoresis if iron studies normal)
   • Anemia of chronic disease
   • Sideroblastic anemia 3, 1

4. Side effect management: Gastrointestinal side effects from oral iron can reduce compliance. Consider:

   • Taking with food (may reduce absorption but improve tolerance)
   • Using alternative iron formulations
   • Switching to IV iron if intolerance persists 2, 4

By following this treatment approach and addressing potential pitfalls, most patients with microcytic iron deficiency anemia will show significant improvement in hemoglobin levels and resolution of symptoms.