Urea concentration in intestinal fluids in normal and uremic dogs

Results from normal and uremic dogs showed that the urea concentrations in gallbladder bile, duodenal, jejunal, ileal, and peritoneal fluids were about the same as that in the serum. When the urea concentration of an unknown body fluid is more than two times that of the serum (whether the subject has normal or abnormal renal function), the tested fluid must have originated in part or in toto from the urinary tract.