This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'Investigation of choice in Thiamine deficiency is \nSelect and explain. \nA. RBC-Thiamine levels, B. RBC - Transketolase levels, C. RBC - Glutathione reductase levels, D. WBC - Ascorbic acid levels', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Severe thiamine deficiency is associated with: Decreased RBC transketolase activity this is the earliest manifestation seen even before clinical disturbances Thiamin is a cofactor of Transketolase pyruvate, alpha-ketoglutarate and lactate level in blood increases in thiamine deficiency ref: DM Vasudevan 8th ed page 467', 'role': 'assistant'}]