In the described blood smear with rod-shaped crystals in hemoglobin, which test is indicated?

In the described blood smear with rod-shaped crystals in hemoglobin, which test is indicated?

• A. Osmotic fragility test
• B. Peroxidase stain
• C. Hemoglobin solubility test
• D. Hemoglobin electrophoresis

Answer: (D)

Rod-shaped crystals seen inside red blood cells on a supravital stain suggest HbH inclusions, which occur in alpha-thalassemia with HbH disease. To identify and characterize the abnormal hemoglobin causing these inclusions, the appropriate test is hemoglobin electrophoresis. It separates normal hemoglobins (HbA, HbA2, HbF) from abnormal variants and will reveal HbH, confirming the diagnosis. The other tests don’t detect or characterize HbH or related hemoglobinopathies: osmotic fragility targets membrane defects like hereditary spherocytosis; peroxidase stain detects white cell enzymes; the Hb solubility test screens for HbS but wouldn’t explain HbH inclusions.

Rod-shaped crystals seen inside red blood cells on a supravital stain suggest HbH inclusions, which occur in alpha-thalassemia with HbH disease. To identify and characterize the abnormal hemoglobin causing these inclusions, the appropriate test is hemoglobin electrophoresis. It separates normal hemoglobins (HbA, HbA2, HbF) from abnormal variants and will reveal HbH, confirming the diagnosis. The other tests don’t detect or characterize HbH or related hemoglobinopathies: osmotic fragility targets membrane defects like hereditary spherocytosis; peroxidase stain detects white cell enzymes; the Hb solubility test screens for HbS but wouldn’t explain HbH inclusions.