NOCTURNAL GROWTH-HORMONE (GH) SECRETION AND GH RESPONSE TO CLONIDINE PROVOCATION IN CHILDREN BEFORE AND AFTER LONG-TERM PREDNISONE THERAPY

Glucocorticoids reduce growth hormone (GH) response to the majority of exogenously administered stimuli and can variably inhibit growth in m an and animals, Recently, however, glucocorticoids have been shown to have varying effects on GH secretion depending on the time of administ ration and, furthermore to be potent secretagogues. We evaluated growt h parameters, GH response to high-dose clonidine and integrated (12-h) nocturnal and mean (12-h) nocturnal GH secretion in 10 prepubertal ch ildren before and after long-term alternate-day prednisone therapy (LT PT). Height standard deviation scores (HtSDS) and growth velocity stan dard deviation scores (GVSDS) decreased significantly after LTPT. GH r esponse to clonidine as well as integrated and mean nocturnal GH secre tion were significantly depressed after LTPT v. before treatment. We c ompared growth parameters and GH data of two groups of children before and after LTPT, Group 1 had low GH peak response to clonidine after L TPT, and group 2 had normal GH response to clonidine. Group 1 children had significantly more impairment of their statural growth and noctur nal GH secretion. Growth parameters (HtSDS and GVSDS) during LTPT corr elated significantly with the peak GI-I response to clonidine (r = 0.6 9 and 0.78, respectively) as well as to the growth parameters before t herapy (r> 0.9), It appears that LTPT impairs both physiologic and pha rmacologically provoked GH secretion and consequently retards growth i n children. However, this effect is variable and is affected by the at tained statural growth before therapy.