Oral clonidine as a growth hormone stimulation test

A single oral dose of 0.15 mg/m2 of clonidine was given to eighteen healthy children and adolescents and to seven patients with hypopituitarism. In healthy subjects there was a pronounced increase in plasma growth hormone from 4.9 +/- 1.3 ng/ml (+/- SEM) to 34.4 +/- 4.5 ng/ml. In the patients with hypopituitarism there was no change in growth-hormone concentrations. Clonidine induced a slight increase in blood glucose in healthy subjects and a slight decrease in patients with hypopituitarism. During the test systolic blood-pressure decreased by a mean of 20 mm Hg in the healthy subjects and by 25 mm Hg in the patients with hypopituitarism. The only side-effect observed was drowsiness. Oral administration of clonidine, a well-tolerated drug, seems to be a simple test for of GH reserves in children and adolescents.