Evaluation of Nutritional Status in Patients on Continuous Ambulatory Peritoneal Dialysis (CAPD)

Abstract

We designed this study to evaluate the nutritional conditions of 16 continuous ambulatory peritoneal dialysis (CAPD) patients. In all these patients we did a monthly 1-day clinical, anthropometrical, biochemical, and nitrogen balance evaluation: a minimum of 3 and a maximum of 9 monthly evaluations in all patients. The results were analyzed in two groups: Group I (N = 8) with neutral or positive nitrogen balances, and Group II (N = 8) with one or more negative nitrogen balances. The sex distribution, mean age in years, time on CAPD, and period of study in this protocol were similar in both groups. Group I maintained a positive nitrogen balance and steady values in the anthropometric measurements (triceps fat fold, upper-arm circumference, body weight). Group II showed a significant decrease in both the anthropometric values and the nitrogen balance during the episodes of peritonitis. In this same group, when peritonitis subsided, the protein intake increased, nitrogen balance became positive, and the anthropometric values improved. When all the nutritional evaluations were analyzed we found a significant and direct linear correlation between nitrogen intake and nitrogen balance in g/kg/day (N = 60; nitrogen balance = nitrogen intake X 0.75 -0.101; r = 0.71; p < 0.001). We also contrasted the presence of peritonitis with the nitrogen balance and the anthropometric values using Spearman rank correlation coefficient and obtained a very high correlation (0.997 to 0.999).

Blood values (blood urea, serum creatinine, serum phosphate, serum potassium, and hemoglobin) were not very sensitive to detect differences within or between groups along the study. The serum proteins and the serum albumin were good markers of the changes in the nutritional conditions of our patients. With the use of the monthly 1-day evaluation, we were able to estimate the initial nutritional conditions at the time of the first assessment and the clinical and nutritional course with the monthly evaluations. The low caloric and proteic intake, during the episodes of peritonitis, were the main cause of malnutrition in this group of CAPD patients and not the peritoneal membrane protein losses as reported in the literature.