Red blood cell transketolase level is a marker for deficiency of:

Vitamin deficiencies and enzyme markersMeasurement of RBC transketolase activity is a reliable disgnostic test to assess thiamine (vitamin B1) deficiency.Assay of the enzyme RBC glutathione peroxidise will be useful in assessing riboflavin (vitamin B2) deficiency.Xanthurenic acid, produced in high quantities is excreted in urine, which serves as a reliable index (paicularly after tryptophan load test) for vitamin B6 deficiency.The excretion of methylmalonic acid (elevated) in urine and estimation of serum B12 level are used to assess B12 deficiency.