Azotemia in upper gastrointestinal hemorrhage. A review.

The cause of the azotemia associated with gastrointestinal hemorrhage has been controversial but review of the literature reveals consistent findings. If extraneous, complicating factors are excluded, the azotemia produced with blood ingestion does not reproduce that seen with gastrointestinal hemorrhage. Azotemia with blood ingestion alone demonstrates a mild peak and usually lasts less than 24 hours, whereas that seen clinically is both higher and longer and a manifestation of blood ingestion plus the renal effects of hypovolemia. The hypovolemia contributes quantitatively more than the digestion of blood and is the sole determinant of azotemia after 24 hours. Consequently, azotemia which persists beyond this time indicates either continuation of bleeding, continuation of hypovolemia insult or intrinsic renal disease. Persistent azotemia following gastrointestinal hemorrhage is an indication for re-evaluation of fluid management.