Utilization of Dexamethasone Suppression Test (DST) in Psychiatric Diagnosis

39 subjects (20 normal controls and 19 major depressive patients) underwent an DST to prove the applicability of the test for the diagnosis of major depressive disorder CDSM-II!). Serum cortisol concentrations were determined in duplicate by radioimmunoassay using Amerlex cortisol RIA kit obtained from Amersham International plc, U,K. The results and conclusions are as follows: 1. Pre-dexamethasone serum cortisol concentrations were most increased at 8 : 00 hour decreasing mostly at 23 : 30 both in normal controls and depressive patients, lessening the probability of disrupted eireadian rhythm in the latter. 2. No significant differences of pre-dexamethasone cortisol levels were found between normal controls and depressive patients(by Student's t-test), 3. Significantly decreased suppressibility of serum cortisol levels occurred in depressive patients within 24 hour after dexamethasone (Irng) administration at S : 00 and 16: 00 hour. No difference was found at 23 : 30 hour (by analysis of covariance). 4. The cortisol values after dexamethasone were definitely more specific as discriminators than the corresponding values before dexamethasone. 5. Significant intergroup differences were revealed in the distribution of suppressors and nonsupressors only when the criterion value of serum cortisol level for nonsuppression was supposed to be above Spg/dl (sensitivity: 26%). That was thought to be due to a limited number of study subjects. 6. Differences in age, sex, body weight, psychopathology, family history of mental illness, recurring episodes of major depression, or associated psychotic features had no bearing upon the distribution of suppressors and nonsuppressors (by Fisher's exact test)