Carbamoylation in chronic renal failure: a comparison of conservative management and continuous ambulatory peritoneal dialysis (CAPD) - abstract

ABSTRACT

In chronic renal failure, the concentration of blood urea increases as the residual function of the kidney decreases, CAPD provides therapy to manage the patient and maintain urea levels at a steady state concentration appropriate for each patient. Although urea is not considered to be a uraemic toxin, cyanate that forms spontaneously from urea reacts with the amino group of amino acids and proteins to form carbamoylated molecules. N-carbamoyl-tyrosine (N-C-Tyr) was measured in a longitudinal study of chronic renal failure and was compared in patients from the U.W.I., Jamaica, managed conservatively with patients from the University of Tennessee, Memphis, managed by CAPD. In post-prandial blood of 5 patients managed by CAPD, the urea mean ñ SD was 22.1ñ4.3 mmol/l and the mean ñ SD for N-C-Tyr was 70 ñ 35 umol/l. The months on CAPD ranged from 7 to 24. The patients managed without dialysis showed a gradual increase in blood urea accompanied by an increase in N-C-Tyr until the time of death. In one patient, the urea level increased from 25 to 82 mmol/l and the N-C-Tyr increased from 51 to 87 umol/l in 10 months. In a second patient, the blood urea level increased from 54 to 77 mmol/l and the N-C-Tyr increased from 59 to 220 in 4 months. In normal individuals, with a blood urea level of 3.6 to 5.7 mmol/l, N-C-Tyr is not found in plasma. This study indicates that CAPD therapy may provide additional benefits by decreasing levels of carbamoylated moieties in patients with chronic renal failure (AU)