Peritoneal loss of growth hormone in children on automated peritoneal dialysis

Objective: To provide quantitative data regarding the daily dialytic loss of growth hormone (GH) in children on peritoneal dialysis (PD). Design: Prospective study involving 24-hour dialysate collections on 3 consecutive days in patients with and without recombinant human GH (rhGH) treatment. Setting: Single-center outpatient PD program. Patients:Twenty-six children undergoing automated PD (APD): 6 with and 20 without daily rhGH. Main Outcome Measures: Daily peritoneal losses of GH, alpha(1)-, beta(2)-microglobulin, transferrin, and albumin. Results:The mean (+/-SEM) daily dialytic GH loss was 2.18 +/- 0.62 mu g/1.73 m(2) per day in rhGH-treated patients and 0.42 +/- 0.28 mu g/1.73 m(2) per day in untreated patients, (p < 0.05). The intraindividual coefficient of variation of daily GH loss was 65%. The peritoneal loss of GH was positively correlated with that of beta(2)-microglobulin (r = 0.77, p < 0.001) and alpha(1)-microglobulin (r = 0.51, p < 0.01). The variability in beta 2-microglobulin and alpha(1)-microglobulin elimination, together with the use of rhGH, explained 66% of the total variability of daily GH excretion. In patients without rhGH therapy, the daily peritoneal GH loss was approximately 0.05% of the estimated daily endogenous production rate based on previous estimates in children with end-stage renal failure. In patients on rhGH therapy, less than 0.1% of the injected rhGH dose was eliminated by dialysis. Conclusion: Peritoneal losses of GH in children on APD account only for a minute fraction of endogenous metabolic clearance, and do not explain the variability of the rhGH treatment response. The assessment of dialytic GH elimination may be used to estimate time-integrated mean plasma GH concentrations, and to monitor rhGH treatment compliance.