Determination of thiamine and its phosphorylated forms in human plasma, erythrocytes and urine by HPLC and fluorescence detection: a preliminary study on cancer patients.

In man, neurotoxicity associated to ifosfamide treatment can be reversed by intravenous thiamine administration. Trying to explain this clinical finding, we decided to study possible changes in thiamine availability and activation in patients exposed to ifosfamide. Free thiamine and its phosphate esters levels were measured in plasma, erythrocytes and urine by an ion-pair HPLC method with pre-column derivatization, which allowed separation of the fluorescent compounds in less than 10 min. The method was validated by linearity, sensitivity and reproducibility studies, whose values met the demands for bioanalytical assays. This method was applied to assess thiamine status in cancer patients exposed to ifosfamide therapy for advanced disease.