Vitamin B1 Status Assessed by Direct Measurement of Thiamin Pyrophosphate in Erythrocytes or Whole Blood by HPLC: Comparison with Erythrocyte Transketolase Activation Assay

(TDP) in erythrocytes is a useful index of thiamin status. We describe an HPLC method for TDP and its results in patients at risk of thiamin deficiency. Methods: We used reversed-phase HPLC with postcol-umn derivatization with alkaline potassium ferricya-nide and fluorescence detection. Samples were depro-teinized and injected directly onto a C18 column. TDP concentrations in erythrocytes were compared with those in whole blood. Reference intervals for erythro-cyte TDP (n 5 147; 79 males and 68 females; mean age, 54 years) and whole blood TDP (n 5 124; 68 males and 56 females; mean age, 54 years) were determined in an apparently healthy population. We compared erythro-cyte TDP with results of the erythrocyte transketolase activation test in 63 patients who were considered at ris