Baseline plasma cortisol and dexamethasone test in unselected psychiatric inpatients.

The plasma cortisol (PC) level at 08.00 a.m. was assessed in 250 unselected psychiatric inpatients suffering from various disorders, assorted in 8 diagnostic groups. Endogenously depressive patients showed a significantly higher rate of cortisol hypersecretion (PC greater than 560 nmol/l = 20 micrograms/dl) than the neurotically or reactively depressed patients and than schizophrenics or paranoid psychotics. The PC level after the midnight dose of 1 mg dexamethasone was examined in 125 patients at 08.00 a.m. (group I) and in 125 patients at 04.00 p.m. (group II). There was no statistical difference in the rate of dexamethasone test (DST) nonsuppressors (PC greater than 140 nmol/l = 5 micrograms/dl) in the separate diagnostic groups between group I and II, but in the postdexamethasone blood samples at 04.00 p.m., significantly more DST nonsuppressors were detected than in the samples at 08.00 a.m. in the total number of all patients, regardless of their diagnosis. DST nonsuppressors were found in all of our diagnostic groups with the exception of manic syndrome, and their various rates will be discussed and compared with the results of previous studies. The DST shows a high sensitivity in endogenous depression, but its diagnostic value is limited as a result of its relative lack of specificity.