ORAL DEXAMETHASONE ADMINISTRATION - NEW PHARMACOLOGICAL TEST FOR THE ASSESSMENT OF GROWTH-HORMONE SECRETION

Acute intravenous (iv) dexamethasone administration has been described recently as a new test for the diagnosis of growth hormone (GH) defic iency. In the present study, a new protocol of dexamethasone administr ation was evaluated. Twelve normal adults and 18 normal prepubertal ch ildren were studied. The dexamethasone iv test was performed in six ad ults at a dose of 4 mg and 12 children at a dose of 2 mg/m(2). Blood s amples were collected 15 min before, at time zero and every 15 or 30 m in during 5 h, resulting in a total of 16 samples. In the remaining si x adults and six children, 8 and 4 mg, respectively, of dexamethasone were administered orally at the subject's home, and blood sampling sta rted 90 min later when they arrived at the hospital. Plasma GH was mea sured by radioimmunassay. The dexamethasone-induced GK response (mean +/- SEM, mu g/l) to the iv or oral protocol did not differ in either t he adults (iv 8.2 +/- 2.1; oral 8.0 +/- 1.6) or the children (iv 14.9 +/- 1.3; oral 13.6 +/- 1.8). It is concluded that the simpler protocol of acute oral dexamethasone administration hereby presented can be a safe and suitable test of GH secretion.