© 1995 by Oxford University Press
research-article |
Defective Clonidine-induced Growth Hormone Secretion and Normal Thyroid and Adrenal Functions in Prepubertal Children with Chronic Renal Insufficiency (CRF)
Departments of Child Health and Nephrology, Royal Hospital Muscat, Oman
Correspondence: Ashraf T. Soliman, Pediatric Endocrinology, Royal Hospital, Seeb 1331, Muscat, Oman.
We evaluated clonidine-induced growth hormone (GH) secretion, insulin-like factor-I (IGF-I), free thyroxine (FT4), and thyroid stimulating hormone (TSH) concentrations, basal (8-h) as well as adrenocorticotrophic hormone (ACTH) provoked cortisol secretion in 14 prepubertal children suffering from chronic renal failure (CRF) with impaired statural growth [growth velocity (GV) = 3.7±03 cm/year] and compared these values with those of 10 normal age matched children with normal variant short stature (NVSS) (GV = 4.6±0.4 cm/year). The body mass indices and the bone age delay did not differ between the two groups (14.8±0.7 kg/m2 and 1.5±035 years v. 13.8 ± 0.48 kg/m2 and 2±0.25 years, respectively). The basal GH concentrations in CRF patients (4.1 ±0.8 µg/l) were significantly higher than those for the NVSS group (1.56 ± 0.2 µg/l). The peak GH response to clonidine was significantly lower in children with CRF (8.4 ±1.7 µg/l) v. (19.6 ±2.3 µg/l) for the control group (P < 0.01). Eight out of the 14 children with CRF did not mount a proper GH response (> 10 µg/l) to clonidine stimulation whereas the GH response of all the children with NVSS was above 10 µg/l. IGF-I concentrations were higher in patients with CRF (35.6 ± 10.9 IU/I) compared to those for the NVSS group (22.1+4.9 IU/I). However, the difference was not statistically significant. There was no significant difference in the FT4, TSH as well as basal (8-h) and ACTH-stimulated cortisol concentrations between the two groups. These data show defective GH release in response to clonidine in children with CRF and suggest the participation of an intrinsic abnormality of the hypothalamic-pituitary growth axis in the aetiology of growth failure in these children.