Sir.—We read with interest the article by Lanes et al1 on the growth hormone (GH) response after clonidine hydrochloride stimulation. This article is the last published of several that showed that clonidine, at different dosages, may induce a GH response.2-4 These articles prompted us to compare the effects of clonidine with betaxolol hydrochloride—glucagon5 or arginine-insulin challenge (standard stimulation) on a GH-induced response.
The population that was studied included eight prepubertal patients seen in the endocrinologic outpatient clinic. The ages ranged from 3 to 13 years (mean, 7.2 years). Five patients were female. The betaxolol-glucagon test was performed four times, and the arginine-insulin test was performed five times as the standard provocative test. The clonidine test was done on the next morning. Clonidine hydrochloride was administered orally at a 0.150—mg/sq m dosage. All tests were performed after an overnight fast.
Blood samples were drawn after 0, 30,