Effects of Estrogen on Growth Hormone Following Clonidine Stimulation

To test the usefulness of estrogen priming to enhance the growth hormone response following stimulation with clonidine hydrochloride in short children. —Randomizedand patient series. —Pediatricendocrine clinic in a referral center. —Seventy-threechildren between 1.8 and 15.4 years of age with growth problems who underwent clonidine GH stimulation tests were randomly assigned to receive either estrogen pretreatment or no pretreatment. An additional 49 subjects, seen before or after the randomized study and who did not receive conjugated estrogen, are also described. —Consecutivesample. —Estrogenpretreatment consisted of 2.5 mg of conjugated estrogen to be taken the evening before and the morning of the clonidine GH stimulation test. Growth hormone concentrations were determined before and 60 and 90 minutes after the subjects received oral clonidine hydrochloride y a laboratory blinded to the subject's estrogen status. Growth hormone concentrations greater than 10 μg/Lwere considered normal. —Eightof the 73 subjects failed both clonidine and arginine-insulin GH stimulation tests. We analyzed the GH data from the 65 GH-sufficient subjects to determine the effect of estrogen pretreatment on the specificity of the clonidine GH stimulation test. There were no statistically significant differences in the mean GH concentrations between the two groups at any time point during the test. —Ourdata demonstrate that estrogen priming does not improve the diagnostic yield of clonidine GH stimulation tests.