What about thalassemia in a patient with microcytic, hypochromic anemia?

Thalassemia in Microcytic Hypochromic Anemia

Thalassemia should be strongly suspected in patients with microcytic hypochromic anemia who have a normal or high RBC count, very low MCV (<70 fl), normal RDW (≤14%), and normal ferritin levels. 1

Differentiating Thalassemia from Iron Deficiency Anemia

Distinguishing between thalassemia trait and iron deficiency anemia is crucial for proper management. The following laboratory parameters are key to making this differentiation:

Parameter	Thalassemia Trait	Iron Deficiency Anemia
MCV	Very low (<70 fl)	Low
RDW	Normal (≤14%)	High (>14%)
Ferritin	Normal	Low (<30 μg/L)
TSAT	Normal	Low
RBC count	Normal/High	Normal/Low
M/H ratio	Increased (in Hb E)	Normal

1, 2

Diagnostic Approach for Suspected Thalassemia

1. Initial Laboratory Evaluation:

   • Complete blood count with RBC indices
   • Serum ferritin
   • Transferrin saturation (TSAT)
   • Peripheral blood smear

2. Additional Testing:

   • Hemoglobin electrophoresis or high-performance liquid chromatography (HPLC)
   • Genetic testing for common alpha and beta thalassemia mutations

3. Specific Findings by Thalassemia Type:

   • Alpha-thalassemia 2: Slightly decreased MCV and CH (hemoglobin content) 3
   • Alpha-thalassemia 1: Increased RBC count with decreased MCV 3
   • Beta-thalassemia: Increased RBC count, decreased MCV, increased HDW (hemoglobin distribution width) 3
   • Hemoglobin H disease: Higher number of hypochromic red cells and decreased CHCM (cellular hemoglobin concentration mean) 3

Management Considerations

Management depends on the type and severity of thalassemia:

• Thalassemia trait/minor: Usually requires no specific treatment but genetic counseling may be appropriate
• Thalassemia intermedia: May require occasional transfusions during periods of stress or infection
• Thalassemia major: Requires regular blood transfusions and iron chelation therapy

For patients requiring iron chelation therapy, deferasirox may be considered, but monitor carefully for:

• Renal toxicity (increased serum creatinine)
• Hepatic toxicity (elevated transaminases)
• Gastrointestinal side effects 4

Common Pitfalls

1. Misdiagnosing thalassemia as iron deficiency: This leads to unnecessary iron supplementation which can be harmful, especially in patients with thalassemia who are prone to iron overload 5, 6

2. Overlooking co-existing conditions: Thalassemia and iron deficiency can coexist, complicating the clinical picture 1

3. Inadequate investigation: Accepting microcytic anemia as iron deficiency without proper evaluation can miss thalassemia diagnoses 1

4. Failing to consider ethnic background: Thalassemias are more common in individuals of Mediterranean, African, Middle Eastern, and Southeast Asian descent 7

Monitoring and Follow-up

• Regular monitoring of hemoglobin levels
• For transfusion-dependent patients, monitoring of iron overload through serum ferritin and/or liver iron concentration
• For patients on iron chelation therapy, regular monitoring of renal function, liver function, and auditory and visual function 4

By using these laboratory parameters and diagnostic approaches, clinicians can effectively differentiate thalassemia from iron deficiency anemia and provide appropriate management for patients with microcytic hypochromic anemia.