<prompt> Which enzyme level is tested in thiamine deficiency?PDHPyruvate kinaseTransketolaseKinase  <response>: 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. 