Hemoglobin electrophoresis / HPLC

What it measures

Separates and measures the different hemoglobin types in red cells. It diagnoses thalassemia traits and variant hemoglobins such as S, C, D and E.

Specimen and preparation

• Specimen: Whole blood (EDTA)
• Tube: Lavender top
• Preparation: Collect before transfusion or wait at least 3 months after one. Iron deficiency can lower HbA2, so check iron status.

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Raised HbA2 (>3.5%): β-thalassemia trait
• Raised HbF: β-thalassemia major/intermedia, HPFH, sickle cell disease
• Presence of HbS, HbC, HbD or HbE variants
• HbH or Hb Bart's: α-thalassemia

Causes of low values

• Low HbA2: iron deficiency, α-thalassemia, δ-β thalassemia

Method

Cation-exchange HPLC or capillary electrophoresis; alkaline/acid gel electrophoresis

Good to know

Interpret with CBC indices and iron studies. α-thalassemia trait often shows a normal pattern and needs DNA testing.

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