An 18-year-old man with intermittent jaundice and splenomegaly has Hb 10.5 g/dL, MCV 74 fL, reticulocytes 7%, and spherocytes on smear. His father had cholecystectomy at age 30 for pigment stones. Osmotic fragility testing is equivocal. What is the most appropriate confirmatory test?

• A Acidified glycerol lysis test
• B Hemoglobin electrophoresis
• C Direct antiglobulin test
• D Eosin-5-maleimide binding flow cytometry ✓

Explanation

Hereditary spherocytosis results from defects in vertical membrane linkages, classically spectrin-ankyrin or band 3, causing membrane loss and spherocyte formation. Eosin-5-maleimide binds band 3 and other membrane proteins; reduced fluorescence confirms diminished membrane surface and is now the standard confirmatory test, especially when osmotic fragility is falsely negative in mild cases. The direct antiglobulin test matters only to exclude immune hemolysis, which this family history already argues against.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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