Effect of age on protein catabolic rate, morbidity, and mortality in uraemic patients with adequate dialysis.

To test the validity of the assumption that the protein catabolic rate (PCRn g/kg/day) is dependent on the normalized dose of dialysis (Kt/V urea), and to try to define the characteristics of the patients in the undefined domain A of the mechanistic map of the National Cooperative Dialysis Study (NCDS), which should include patients with adequate amount of dialysis but inadequate PCRn, urea kinetic modelling was performed over 12 months on 85 patients undergoing haemodialysis. All the patients were managed to maintain a Kt/V urea > or = 0.9. During the entire period of study the total number of hospitalizations and the number of days of hospitalization were recorded. Total serum proteins and serum albumin concentrations were measured at the start and at the end of the study. The results of the study show that there was no correlation between Kt/V and PCRn nor between Kt/V and patient's age, but there was a strong inverse correlation between age and PCRn (r = 0.578; P < 0.0001). Further division of the patients into four groups according to age showed that the lowest values of PCRn were for the group of patients > or = 75 years old. Twelve patients with PCRn < or = 0.8 and Kt/V > or = 0.9 were included in domain A of the mechanistic map. Eleven (92%) of these 12 patients were > or = 65 years old. No correlations were found between the total number of hospitalizations, the total days of hospitalization, Kt/V, time on HD, body weight and PCRn by multiple regression analysis, while the inverse correlation between PCRn and age was confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)