Blunted growth hormone response to clonidine in Gilles de la Tourette syndrome.

Noradrenergic mechanisms have been involved in the pathogenesis of Gilles de la Tourette Syndrome (GTS). Since the central alpha 2 adrenergic agonist clonidine is widely used as a therapeutic agent in GTS, the present study aimed at assessing whether GH release after clonidine, representing central alpha 2-adrenergic receptor sensitivity, was altered in GTS. After administration of 2 micrograms/kg body weight clonidine, the GH response was examined in nine drug-free, alcohol-abstinent GTS patients (eight men, one woman) and in nine age- and sex-matched abstinent healthy controls. A blunted response of GH release (< 5 ng/ml) was observed in seven patients and the area under the curve (AUC) of the GH-release was significantly reduced (p < .01) compared to controls. This finding indicates an involvement of the noradrenergic system in GTS.