Biologically active form of vitamin B1 in human peritoneal effluent

Supplementation with vitamin B1 protects the peritoneal membrane from inflammatory and oxidative insults and preserves residual kidney function in rat models of peritoneal dialysis (PD). It is assumed that an active form of vitamin B1, thiamin diphosphate (ThDP), is responsible for this protective effect. However, it has never been shown whether ThDP, a compound known not to cross cellular membranes, is actually detectable in human peritoneal effluent. This study was designed to investigate the concentration, appearance rate, and daily loss of ThDP in the peritoneal effluent of patients treated with PD. We performed 24-hour effluent collection as well as the peritoneal equilibration test (PET) and analyzed the relation between the transport characteristics of the peritoneal membrane and appearance rate of ThDP in a cohort of 26 PD patients. ThDP was detectable in peritoneal effluent in humans. ThDP appearance rate was independent of the transport characteristic of peritoneal membrane, and was not associated with peritoneal transport of other small solutes. We conclude that ThDP can be found in detectable concentrations in the peritoneal effluent in humans and is transported through the peritoneal membrane in a pattern independent of other small solutes. Our finding opens novel opportunities in further research on the protection of peritoneal membrane in humans.