Low-dose (0.5-mg) dexamethasone suppression test in depressive patients

Fifty-six depressive patients underwent a low-dose (0.5-mg) Dexamethasone Suppression Test (DST). Blood samples for cortisol assay were obtained twice on day 2, and the plots of the sum of the two cortisol values formed two groups, consisting, respectively, of suppressors and nonsuppressors. Nineteen (73.1%) of 26 patients with major depressive episodes (MDE) showed nonsuppression, as well as 12 of 15 MDE patients with melancholia, 3 of 3 with psychotic features, 3 of 4 with bipolar or atypical bipolar affective disorder, and 1 of 4 without melancholia. The specificity, calculated from the data of 53 patients (excluding 3 who were already known to be false-positive on the DST) was 85.2%, and the diagnostic confidence was 82.6%. The DSTs were reexamined in the 11 MDE patients showing nonsuppression, 8 of whom became suppressors with remission of the depressive symptoms.