Plasma level and transfer capacity of thiamin in patients undergoing long-term hemodialysis

Water-soluble vitamins have a molecular size small enough to pass through the membrane of an artificial kidney. This fact has led to the suggestion that these vitamins be substituted in patients undergoing long-term hemodialysis. In sharp contrast to this general belief, our study has shown that the plasma thiamin levels in patients on long-term hemodialysis were not different from those found in normal subjects. It also remained unchanged before and after the dialysis, althoug thiamin was obviously removed in in vitro dialysis. Accordingly, dietary thiamin appears to be sufficient, making further supplementation unnecessary.