Mannitol absorption and excretion in uremic patients regularly treated with gastrointestinal perfusion.

About 7.2% of ingested mannitol is absorbed during gastrointestinal perfusion in uremic patients. The absorbed mannitol is excreted by the kidney and also by an extrarenal route. The extrarenal mannitol clearance is estimated to be 1.95 ml/min, which is insufficient to remove absorbed mannitol in anuric patients. This imposes restrictions on the application of gastrointestinal perfusion in therapy of uremia in anuric or oliguric patients.