Nutritional thiamine status in a patient with suspected deficiency is best assessed by measuring the activity of which erythrocyte enzyme?

• A Transketolase ✓
• B Glucose-6-phosphate dehydrogenase
• C Pyruvate kinase
• D Methionine synthase

Explanation

Transketolase of the hexose monophosphate shunt requires thiamine pyrophosphate (TPP) as a coenzyme, and red cells contain measurable transketolase activity. Erythrocyte transketolase activity, and its stimulation after adding TPP in vitro (TPP effect), is the standard functional test for thiamine deficiency. Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase also need TPP but are not assayed in erythrocytes. Glucose-6-phosphate dehydrogenase uses NADP, and methionine synthase uses methylcobalamin, so neither reflects thiamine status.

Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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