Six-month overnight administration of intraperitoneal amino acids does not improve lean mass

Intraperitoneal administration of 1% amino acid dialysis solution in patients on continuous peritoneal dialysis (CAPD) is associated with improvement in plasma amino acid concentrations and inconsistent results with respect to nitrogen balance. Whether alteration(s) in lean mass and body fat distribution also occur remains controversial. Therefore 18 patients (P), on CAPD for at least 6 months, were assigned in a prospective and controlled fashion to receive overnight either a 1% amino acid (AA-P) or a 1.36% glucose (Glu-P) containing dialysis solution. Body composition was investigated using whole body dual energy X-ray absorptiometry (Hologic QDR 1000/W). In P receiving glucose (n = 9), total body fat mass increased (+1.0 +/- 0.4 kg, mean +/- SEM, p < 0.03), whereas in patients on amino acids (n = 9), it decreased (-0.6 +/- 0.3, p < 0.02). This decrease in fat mass in AA-P was attributable to a decrease in upper body fat (-0.6 +/- 0.2, p < 0.02), whereas in Glu-P, it increased (+0.9 +/- 0.03, p < 0.03). No change in lower body fat was observed in either group. Total body lean mass remained similar in both groups during the six months of study (AA-P: 46.6 +/- 2.9 kg vs 47.0 +/- 3.0 kg, Glu-P 50.8 +/- 3.2 vs 50.1 +/- 2.2 kg baseline vs 6 months, respectively). In AA-P plasma urea concentrations increased from 25 +/- 2 to 34 +/- 3 mmol/l (p < 0.05), whereas plasma bicarbonate concentrations were similar before and after 6 months of therapy in either group. Plasma albumin and transferrin concentrations did not change in either group. Protein catabolic rate increased in AA-P (p < 0.01), whereas K x t/V did not change as a consequence of either therapy.

Reduction in the amount of glucose in the peritoneal dialysate and the addition of amino acids decreases, whereas continuous dialysis with overnight glucose increases upper body fat over a 6-month period. However, no changes in protein stores were observed with the addition of amino acids. Therefore overnight peritoneal dialysis with amino acids offers minor advantages to protein-malnourished patients on CAPD, but may be of benefit in overweight CAPD patients.