Nocturnal growth hormone (GH) secretion and GH response to clonidine provocation in children before and after long-term prednisone therapy.

Abstract

Glucocorticoids reduce growth hormone (GH) response to the majority of exogenously administered stimuli and can variably inhibit growth in man and animals. Recently, however, glucocorticoids have been shown to have varying effects on GH secretion depending on the time of administration and, furthermore, to be potent secretagogues. We evaluated growth parameters, GH response to high-dose clonidine and integrated (12-h) nocturnal and mean (12-h) nocturnal GH secretion in 10 prepubertal children before and after long-term alternate-day prednisone therapy (LTPT). Height standard deviation scores (HtSDS) and growth velocity standard deviation scores (GVSDS) decreased significantly after LTPT. GH response to clonidine as well as integrated and mean nocturnal GH secretion were significantly after LTPT. GH response to clonidine as well as integrated and mean nocturnal GH secretion were significantly depressed after LTPT v. before treatment. We compared growth parameters and GH data of two groups of children before and after LTPT. Group 1 had low GH peak response to clonidine after LTPT, and group 2 had normal GH response to clonidine. Group 1 children had significantly more impairment of their statural growth and nocturnal GH secretion. Growth parameters (HtSDS and GVSDS) during LTPT correlated significantly with the peak GH response to clonidine (r=0.69 and 0.78, respectively) as well as to the growth parameters before therapy (r > 0.9). It appears that LTPT impairs both physiologic and pharmacologically provoked GH secretion and consequently retards growth in children. However, this effect is variable and is affected by the attained statural growth before therapy.