THE DESMOPRESSIN STIMULATION TEST IN THE DIFFERENTIAL-DIAGNOSIS OF CUSHINGS-SYNDROME

OBJECTIVE We assessed the ability of desmopressin to stimulate the pit uitary-adrenal axis in patients with Cushing's syndrome. DESIGN AND SU BJECTS The cortisol response to 5 or 10 mug of intravenous desmopressi n was evaluated in 31 patients with Cushing's syndrome of several aeti ologies and in 15 normal subjects. RESULTS Cortisol responses were obs erved in 15 out of 16 patients with pituitary dependence and in two pa tients with adrenal nodular hyperplasia, the increase above baseline r anging from 61 to 379% in the responders. Eight patients with adrenal tumours and one with the ectopic ACTH syndrome did not respond to desm opressin, having shown changes in their cortisol levels from -5 to 42% above baseline. Responses occurred in two out of the 15 normal indivi duals, whose cortisol increased 58 and 69% above baseline, respectivel y. Stimulation tests with standard agents as lysine vasopressin or ovi ne corticotrophin-releasing hormone were performed in the same patient s and there was a high degree of concordance. No serious adverse react ions were observed in the tests with desmopressin. CONCLUSIONS Desmopr essin was able to stimulate the Pituitary-adrenal axis in patients wit h Cushing's disease and, like corticotrophin releasing hormone, it may prove useful in the differential diagnosis of Cushing's syndrome.