What is the diagnosis based on this CBC showing microcytic hypochromic anemia?

Interpretation of CBC: Microcytic Hypochromic Anemia

This CBC shows a classic pattern of iron deficiency anemia with microcytic hypochromic parameters (low MCV, MCH, and MCHC) and elevated RDW. 1

CBC Analysis:

• Hemoglobin: 9.8 g/dL (decreased)
• Hematocrit (PCV): 30.8% (decreased)
• MCV: 71.6 fL (decreased, microcytic)
• MCH: 23.0 pg (decreased, hypochromic)
• MCHC: 32.1 g/dL (low normal)
• RDW: 18.7% (markedly elevated)
• WBC (TLC): 6.72 (normal)
• RBC: 4.24 (relatively preserved)
• Platelet count: 203 (normal)
• MPV: 11.8 (normal)

Diagnostic Interpretation:

Primary Diagnosis: Iron Deficiency Anemia

The combination of:

• Low hemoglobin (9.8 g/dL)
• Microcytosis (MCV 71.6 fL)
• Hypochromia (MCH 23.0 pg)
• Markedly elevated RDW (18.7%)

This pattern strongly suggests iron deficiency anemia, which is the most common cause of microcytic hypochromic anemia worldwide (approximately 80% of all anemia cases) 2.

Differential Diagnosis:

1. Iron Deficiency Anemia

   • Most likely diagnosis based on the markedly elevated RDW (18.7%)
   • RDW elevation is characteristic of iron deficiency and helps distinguish it from thalassemia 1

2. Thalassemia

   • Possible but less likely due to the very high RDW
   • Thalassemia typically presents with normal RDW despite very low MCV 1
   • Would need hemoglobin electrophoresis to confirm/exclude

3. Anemia of Chronic Disease

   • Less likely as a sole cause given the degree of microcytosis and hypochromia
   • Could be present as a comorbid condition

4. Sideroblastic Anemia

   • Rare genetic disorders affecting heme synthesis 3
   • Would require bone marrow examination showing ring sideroblasts

Next Steps in Management:

1. Confirm iron deficiency with:

   • Serum ferritin (most sensitive test; <15 μg/L confirms iron deficiency) 1
   • Transferrin saturation (low in iron deficiency)
   • Consider CRP to assess for inflammation which can elevate ferritin 1

2. Investigate underlying cause of iron deficiency:

   • Gastrointestinal blood loss (most common in adults)
   • Menstrual blood loss (in premenopausal women)
   • Malabsorption (celiac disease, post-gastrectomy)
   • Dietary insufficiency (more common in infants, children, pregnant women)

3. Treatment:

   • Oral iron supplementation: ferrous sulfate 200mg three times daily 1
   • Continue for 3 months after hemoglobin normalizes to replenish stores
   • Monitor response with repeat CBC in 2-4 weeks (expect hemoglobin rise of ≥1 g/dL)

Common Pitfalls to Avoid:

• Failure to investigate the cause of iron deficiency, especially in adult men and postmenopausal women where GI bleeding must be excluded 1
• Misinterpreting ferritin levels in the presence of inflammation (ferritin is an acute phase reactant) 1
• Relying solely on MCV/MCH without confirming iron status with appropriate tests 1
• Stopping iron therapy prematurely before replenishing iron stores (continue for 3 months after hemoglobin normalizes) 1

Special Considerations:

• If oral iron is not tolerated or ineffective, consider IV iron therapy 1
• In cases with severe anemia or hemodynamic compromise, blood transfusion may be necessary
• For patients with persistent unexplained iron deficiency despite treatment, consider referral to a hematologist