Effect of selenium supplementation on the distribution of selenium among plasma proteins of a patient with maple syrup urine disease.

Selenium (Se) status was studied in a patient with classical maple syrup urine disease (MSUD) receiving Se supplement. The basal plasma Se concentration was 0.06 mumol/l increasing to 2.1 mumol/l after 40 days of supplementation. When the plasma Se distribution was analysed by gel filtration, a major peak was seen close to the high molecular weight proteins with a second peak in the albumin region. When the Se dose was decreased in a stepwise manner from 50 micrograms/day to 25 micrograms/day and then to 17 micrograms/day plasma Se decreased, but the proportion of plasma Se in the two protein peaks did not change. In a healthy girl not supplemented with Se, the proportion of plasma Se in the albumin region was somewhat lower. In the MSUD patient glutathione peroxidase activity was initially low, and increased ten-fold during Se supplementation. The study indicates that the Se requirement for plasma glutathione peroxidase activity was fulfilled at the lowest dose of Se used and that Se is incorporated into several plasma proteins after supplementation.