What is the appropriate management for a patient with microcytic hypochromic anemia and elevated RDW?

Management of Microcytic Hypochromic Anemia with Elevated RDW

The patient with microcytic hypochromic anemia and elevated RDW should undergo comprehensive gastrointestinal evaluation including upper endoscopy with small bowel biopsy and colonoscopy to rule out gastrointestinal blood loss, while simultaneously starting oral iron supplementation. 1, 2

Diagnostic Interpretation

The CBC results show:

• Low hemoglobin (8.5 g/dL) and hematocrit (26.5%)
• Low MCV (97.4 fL) indicating microcytosis
• Normal MCH (31.3 pcg) and MCHC (32.1 g/dL)
• Elevated RDW (14.0%) indicating anisocytosis
• Normal WBC and platelet counts

This pattern is highly suggestive of iron deficiency anemia (IDA), which is characterized by:

• Microcytosis (low MCV)
• Elevated RDW (reflecting heterogeneous red cell population)
• Progressive decrease in hemoglobin

Initial Management Steps

1. Iron Studies:

   • Measure serum ferritin (most sensitive test for iron deficiency)
   • Check transferrin saturation (values <30% support iron deficiency)
   • Consider C-reactive protein to assess for inflammation (which can falsely elevate ferritin) 1, 2

2. Initiate Iron Therapy:

   • Start oral iron supplementation (ferrous sulfate 200 mg three times daily)
   • Continue for 2-3 months after hemoglobin normalizes to replenish iron stores
   • Consider adding ascorbic acid to enhance absorption 2

3. Gastrointestinal Investigation:

   • Upper GI endoscopy with small bowel biopsies (to rule out malabsorption and check for celiac disease)
   • Colonoscopy or barium enema (especially important in patients >45 years)
   • These investigations are essential as GI blood loss is the most common cause of IDA in adult men and post-menopausal women 1

Follow-up and Monitoring

1. Repeat CBC after 4 weeks to assess response to iron therapy

   • Expect hemoglobin rise of approximately 2 g/dL after 3-4 weeks of therapy 2

2. Continue iron therapy for 2-3 months after normalization of hemoglobin

3. If poor response to oral iron, consider:

   • Medication adherence issues
   • Ongoing blood loss
   • Malabsorption
   • Consider switching to IV iron if oral therapy fails 2

Special Considerations

• Differential Diagnosis: While iron deficiency is most likely given the microcytosis and elevated RDW, other conditions to consider include:

  • Thalassemia trait (typically has normal or only slightly elevated RDW)
  • Anemia of chronic disease
  • Sideroblastic anemia 3

• RDW Interpretation: Although elevated RDW is characteristic of iron deficiency, it is not perfectly specific. Studies show that while most iron-deficient cases have increased RDW, up to 48% of thalassemia cases may also present with increased RDW 4, 5

Common Pitfalls to Avoid

1. Incomplete investigation of underlying cause - never assume dietary deficiency without ruling out blood loss

2. Misdiagnosis due to inflammation - inflammatory conditions can elevate ferritin despite iron deficiency

3. Premature discontinuation of iron therapy before replenishing iron stores

4. Failure to obtain small bowel biopsies during endoscopy (2-3% of IDA patients have celiac disease) 1

5. Inappropriate iron supplementation in conditions like thalassemia trait where iron overload is a risk 2

By following this approach, you can effectively diagnose and treat the underlying cause of microcytic hypochromic anemia with elevated RDW, improving patient outcomes and quality of life.