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, alpha1-, beta2-microglobulin, transferrin, and albumin.
Results: The mean (+/-SEM) daily dialytic GH loss was 2.18+/-0.62 microg/1.73 m2 per day in rhGH-treated patients and 0.42+/-0.28 microg/1.73 m2 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 beta2-microglobulin (r = 0.77, p < 0.001) and alpha1-microglobulin (r = 0.51, p < 0.01). The variability in beta2-microglobulin and alpha1-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.