[The diagnosis of Cushing's disease by the nocturnal dexamethasone administration test].

Prospective study performed at the General Hospital, National Medical Center, XXI Century, Endocrinology Ward, Mexico-City, to compare the diagnostic sensitivity in Cushing's disease of the oral high doses (8 mg) dexametazone suppression test in single doses with nocturnal administration (DXM-N) and the classic doses of two days (DXM-C). Fourteen patients with hypercortisolism were studied; on thirteen the hypophyseal origin was surgical confirmed. Sensitivity of high doses of oral dexametazone test was proved by using serial samples of serum cortisol; the Fisher test was used for analysis of the suppression of serum cortisol after the test was done.