Growth hormone--insulin-like growth factor-I (IGF-I) axis in prepubertal children with chronic renal failure.

Abstract

The hypothalamic-pituitary insulin-like growth factor I (IGF-I) axis was evaluated in 12 children with chronic renal failure (CRF) aged 3.2 to 16.5 yr (mean 9.5) on chronic dialysis, and in 13 renal transplantation patients aged 7.5 to 15.0 yr (mean 11.1). Height standard deviation score (SDS) was -2.8 +/- 0.5 (mean +/- SE) and -3.0 +/- 0.3 SDS (p = NS), and growth velocity was 3.7 +/- 0.4 and 1.5 +/- 0.3 cm/year (p < 0.01), respectively. Mean nocturnal growth hormone (mean GH) and number of pulses > 5 ng/ml in CRF and transplantation children were 4.2 +/- 0.8 vs 2.4 +/- 0.3 ng/ml, p = 0.08 and 1.7 +/- 0.2 vs 1.0 +/- 0.2, p < 0.05, respectively. In transplant children there was a positive correlation between mean GH and growth velocity (p < 0.02). GH peak response and the area under the curve post GH releasing hormone test were significantly higher in CRF and transplant children treated with deflazacort (new steroid derived from prednisolone) vs transplant children treated with methylprednisone. Mean serum IGF-I levels were -0.5 +/- 0.2 SDS for chronological age (CA) in CRF patients and +0.8 +/- 0.2 SDS(CA) in transplant patients, p = NS. In the latter, serum IGF-I values were positively correlated with growth velocity (p < 0.02) and negatively correlated with methylprednisone dose (p < 0.05). Patients with CRF and growth retardation have a higher number of GH peaks and slightly elevated mean GH levels compared to transplant patients. After renal transplantation GH secretion may be influenced by glucocorticoids as shown by the lower GH response to GHRH which improved with deflazacort and the inverse correlation between methylprednisone dose and IGF-I levels.