Metabolism USMLE Step 1 Practice Question
An infant receives an exchange blood transfusion due to severe neonatal jaundice. Red blood cell transfusion is required monthly, and at 6 months of age, a splenectomy is performed. Histologic examination of the spleen reveals marked hemosiderosis. Laboratory studies show: RBC 2.54x10^6/mm^3 (normal 3.5-5.5), Hemoglobin 8.3 g/dL (normal 12-16), Hematocrit 23.4% (normal 34-46%), Reticulocytes 27% (normal 0.5-1.5%), Indirect bilirubin 6.1 mg/dL (normal 0.4-3.4). Analysis of red cell glycolytic intermediates indicates markedly elevated concentrations of 2,3-bisphosphoglycerate, 3-phosphoglycerate, 2-phosphoglycerate, and phosphoenolpyruvate. Which of the following is the most likely diagnosis?
Answer choices
- ASickle cell anemia
- BGlucose-6-phosphate dehydrogenase (G6PD) deficiency
- Cβ-Thalassemia
- DLead poisoning
- EPyruvate kinase (PK) deficiencyCorrect answer
- FHereditary spherocytosis
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