Total-body nitrogen by neutron activation in maintenance dialysis

The nutritional status of 35 patients on continuous ambulatory peritoneal dialysis (CAPD) was assessed by the traditional methods of dietary history and anthropometric measurements, and was compared with simultaneous measurements of dietary protein intake (DPI) calculated from urea generation rate and total-body nitrogen (TBN) assessment by prompt neutron activation analysis (PNAA). DPI as determined by dietary recall was significantly higher than calculated DPI (1.04 +/- 0.42 v 0.84 +/- 0.28 g/kg/d; P less than 0.001). Anthropometric measurements did not differ significantly from the predicted normal values for sex, height, and age. However, PNAA measurements of TBN demonstrated significant nitrogen depletion, being 88.2% of normal for males (P less than 0.001) and 87.5% of normal for females (P less than 0.002); TBN correlated significantly with DPI calculated from urea generation rate (P less than 0.05). Assessment of these 35 patients 17.5 +/- 4.4 months later, demonstrated that patients who died or suffered serious morbidity requiring transfer from CAPD (n = 10) had significantly lower TBN than those who remained on CAPD or underwent successful renal transplantation (n = 25): 80.0% v 93.2% of normal (P less than 0.01). No difference in anthropometric measurements was observed between the two groups of patients. Eleven patients on maintenance home or satellite hemodialysis underwent identical dietary, anthropometric, and TBN assessments and results were similar to those obtained in the CAPD population, although no correlation with calculated DPI and TBN was observed.(ABSTRACT TRUNCATED AT 250 WORDS)