Sickle Cell Anemia: The Daily PANCE Blueprint

The answer is C. Hemoglobin electrophoresis.

Which test is most definitive for diagnosing sickle cell anemia?

A. Bone marrow biopsy B. Complete blood count (CBC) C. Hemoglobin electrophoresis D. Peripheral blood smear E. Serum iron level

The correct answer is C. Hemoglobin electrophoresis.

Hemoglobin electrophoresis is the gold standard diagnostic test for sickle cell anemia. This test separates different types of hemoglobin based on their electric charge and movement pattern through a gel medium. In sickle cell anemia, hemoglobin electrophoresis typically shows predominantly hemoglobin S (HbS) with absence of hemoglobin A (HbA) in homozygous patients (HbSS disease). The test can also identify other hemoglobinopathies and differentiate between sickle cell trait (heterozygous HbAS) and sickle cell disease (homozygous HbSS). Modern techniques include high-performance liquid chromatography (HPLC) and isoelectric focusing, which provide quantitative measurements of different hemoglobin types. This definitive test is essential for confirming the diagnosis and differentiating sickle cell anemia from other hemoglobinopathies and anemias.

Incorrect Answer Explanations:

• A. Bone marrow biopsy is invasive and not necessary for diagnosing sickle cell anemia. While it may show erythroid hyperplasia in response to chronic hemolysis, it doesn’t identify the specific hemoglobin abnormality that defines sickle cell disease.
• B. Complete blood count (CBC) can show anemia, increased reticulocyte count, and elevated WBCs, but these findings are nonspecific. A CBC alone cannot confirm the presence of hemoglobin S or differentiate sickle cell disease from other hemolytic anemias.
• D. Peripheral blood smear may show characteristic sickle-shaped RBCs, but these cells are not always present (especially if the patient is on hydroxyurea therapy). The presence of sickle cells is suggestive but not definitive, as they can also be seen in sickle cell trait and other hemoglobinopathies.
• E. Serum iron level is not useful in diagnosing sickle cell anemia. It may actually be elevated in sickle cell patients due to frequent blood transfusions leading to iron overload, but this is a complication rather than a diagnostic finding