Urea kinetics evaluation of hemodialysis and CAPD patients.

Urea kinetics have been used to measure adequacy of hemodialysis. The role of urea kinetics in CAPD has not been clearly established. Using urea kinetics, we studied 71 hemodialysis and 71 CAPD patients. Age was 53 +/- 12 and 45.8 +/- 12 respectively. Urea kinetics in hemodialysis were studied in the standard manner. CAPD patients collected 24 hr, dialysate fluid to measure urea, creatinine, glucose and protein. Urine was collected for 24 hr. to measure urea and creatinine. Protein catabolic rate (pcr) was calculated from the total amount of urea cleared in 24 h. Both groups of patients had similar body weight. Kt/V in CAPD (0.65 +/- 0.1) was at a level considered underdialysis for hemodialysis. In both groups, pcr increased as Kt/V increased. However, CAPD patients had levels of pcr higher than hemodialysis patients at the same level of Kt/V. BUN, serum albumin and serum potassium were significantly lower in CAPD patients. Patients who dialyze more, eat more. Differences in protein intake may be due to a more liberal diet in CAPD, patient selection, removal of middle molecules, or better control of the acidosis.