Plasma amino acid levels and amino acid losses during continuous ambulatory peritoneal dialysis

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Abstract
Free amino acid losses into dialysate during a 24-h collection period and postabsorptive plasma amino acid concentrations were measured in 14 studies in nine clinically stable men undergoing continuous ambulatory peritoneal dialysis. Patients ingested diets containing 97 ± 18 (SD) g/day of protein in a metabolic research unit. Total amino acid losses were 3.4 ± 1.2 g/24 h and represented 3.9 ± 1.9% of total nitrogen output (in dialysate, urine, and feces). The sum of plasma essential, nonessential, and total amino acid concentrations was normal, although plasma valine, leucine, and isoleucine were decreased and several amino acids were elevated. Neither plasma nor dialysate amino acids varied with protein intake. Dialysate amino acid concentrations averaged 72 ± 18% of plasma levels, and 29.0 ± 3.6% of dialysate amino acids were essential. Dialysate concentrations and 24 h losses of individual amino acids each correlated with plasma levels (r = 0.83 and 0.78, respectively). Thus during continuous ambulatory peritoneal dialysis, postabsorptive plasma amino acids are, in general, well maintained. Daily losses of free amino acids during continuous ambulatory peritoneal dialysis are rather small and are easily replaced by food intake.