Changes in blood urea nitrogen measured at different times after dialysis

Sequential changes in BUN measured at the end of and after hemodialysis. A is the immediate postdialysis sample; B is an immediate postdialysis sample taken from the limb opposite the vascular access to eliminate access recirculation; C is delayed for two minutes to eliminate the effect of cardiopulmonary recirculation; and D is delayed for one hour when urea equilibration should be complete.