This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Biochemistry
Which enzyme level is tested in thiamine deficiency? 
Select and explain. 
A. PDH, B. Pyruvate kinase, C. Transketolase, D. Kinase
C: Transketolase
Answer: C: Transketolase 
Explanation: Thiamine (vitamin B1) Deficiency It is assessed by Erythrocyte transketolase activity. Thiamine (Vitamin B1) is the marker for transketolase enzyme -which is involved in HMP pathway (in RBCs) Activity of Transketolase is measured (not the quantity).