Objective: To provide accurate measurement of renal function during treatment with recombinant human growth hormone (rhGH).
Methods: We measured glomerular filtration rate and effective renal plasma flow by clearance of inulin and para-aminohippuric acid before rhGH therapy, after 1 week, and then at 6-month intervals for up to 2 years of treatment in 16 children (mean (SD) age = 13.1 (2.2) years; glomerular filtration rate = 52 (27) ml/min per 1.73 m2). The mean (SD) time from transplantation was 6.5 (3.6) years.
Results: Linear growth velocity during rhGH therapy increased from 4.0 (1.8) to 8.8 (2.6) cm/yr (p < 0.0001). One child was withdrawn after 9 months because of abnormal glucose tolerance, and another child received a second renal transplant after 18 months. Glomerular filtration rate increased to 57 (29) ml/min per 1.73 m2 at 1 week (p = 0.004), remained improved at 6 months (63 (30); p = 0.013), but was not significantly better at 1 year (59 (33)). Effective renal plasma flow on day 1 was 237 (127) ml/min per 1.73 m2 and was unchanged on day 8 (244 (123)), at 6 months (271 (149)), and after 1 year (269 (157)). During the study there was no significant change in filtration fraction, blood pressure, or kidney volume, and excretion of microalbumin and N-acetylglucosaminidase was unaltered. There was one rejection episode per 14.8 patient-months in the year before treatment, 1 per 18.9 patient-months during the first year of treatment, and 1 per 13 patient-months during the second year of rhGH therapy.
Conclusion: Treatment with rhGH improves growth in children with renal transplants. Glomerular filtration rate was increased after 1 week and 6 months of rhGH therapy but returned to baseline values thereafter. The data indicate the need for long-term follow-up of children with renal transplants who are receiving rhGH.