<prompt> Test to diagnose thiamine deficiency -RBC transketolaseFIGLU excretionMethyl-malunic acid in urineHistidine load test  <response>: Ans. is a i.e., RBC transketolase o Thiamine diphosphate is also the coenzume for transketolase, in the pentose phosphate pathway. Therefore, thiamine nutritional status is best assessed by erythrocyte preferred or whole blood transketolase activity. 