What is the treatment for microcytic anemia?

Treatment of Microcytic Anemia

Oral iron supplementation with 35-65 mg of elemental iron daily is the first-line treatment for microcytic anemia caused by iron deficiency, with ferrous sulfate 200 mg twice daily for 3 months being the recommended regimen. 1

Diagnostic Approach

Before initiating treatment, it's essential to determine the specific cause of microcytic anemia:

1. Laboratory evaluation:

   • Complete blood count with MCV < 80 fl indicating microcytosis
   • Iron studies:
     • Serum ferritin (< 30 μg/L confirms iron deficiency)
     • Transferrin saturation (< 30% suggests iron deficiency)
     • C-reactive protein (to rule out inflammation affecting ferritin)

2. Differential diagnosis of microcytic anemia:

Parameter	Iron Deficiency	Thalassemia Trait	Anemia of Chronic Disease
MCV	Low	Very low (<70 fl)	Low/Normal
RDW	High (>14%)	Normal (≤14%)	Normal/Slightly elevated
Ferritin	Low (<30 μg/L)	Normal	Normal/High
TSAT	Low	Normal	Low
RBC count	Normal/Low	Normal/High	Normal/Low

Treatment Algorithm

1. Iron Deficiency Anemia (Most Common Cause)

• First-line therapy:

  • Oral ferrous sulfate 200 mg twice daily (providing 65 mg elemental iron per tablet) 1, 2
  • Continue treatment for 3 months after hemoglobin normalizes to replenish iron stores
  • Do not crush or chew tablets 2

• Alternative oral preparations:

  • Ferrous fumarate or ferrous gluconate if sulfate not tolerated 1

• Second-line therapy (for non-responders or intolerant patients):

  • Parenteral iron preparations (iron sucrose, ferric carboxymaltose, or iron dextran) 1
  • Consider parenteral iron for patients with:
    • Malabsorption
    • Blood losses exceeding oral replacement capacity
    • True intolerance to oral preparations 3

2. Thalassemia

• Treatment depends on severity:
  • Thalassemia minor/trait: Usually no specific treatment required
  • Thalassemia major: Blood transfusions and iron chelation therapy 4

3. Sideroblastic Anemia

• Treatment varies by specific genetic defect:
  • XLSA (ALAS2 defect): Trial of pyridoxine 50-200 mg daily initially, then 10-100 mg maintenance if responsive 4
  • SLC25A38 defects: Hematopoietic stem cell transplantation is recommended as the only curative option 4
  • Symptomatic treatment: Erythrocyte transfusions and chelation therapy 4

Monitoring and Follow-up

• Monitor hemoglobin and iron studies at 3-month intervals for one year 1
• Assess response to oral iron therapy within 4-8 weeks
• Investigate underlying cause of iron deficiency:
  • Upper GI endoscopy with duodenal biopsies
  • Colonoscopy or barium enema, especially if no obvious cause is found 1

Common Pitfalls to Avoid

1. Inadequate treatment duration: Failing to continue iron therapy for 3 months after hemoglobin normalization 1

2. Overlooking the underlying cause: Attributing iron deficiency solely to menstrual loss without proper GI investigation 1

3. Missing concomitant deficiencies: Failing to check for coexisting vitamin B12 and folate deficiencies 1

4. Inappropriate iron dosing: Using too low a dose or improper administration (with meals rather than on empty stomach)

5. Overlooking iron overload: In certain genetic disorders like sideroblastic anemia, iron overload can be more harmful than the anemia itself and requires monitoring 4

By following this structured approach to diagnosis and treatment, most patients with microcytic anemia can be effectively managed, with significant improvements in morbidity, mortality, and quality of life.