The cortisol suppression index and the dexamethasone suppression test in major depression

The pre- and postdexamethasone cortisol levels are determined at 8 a.m. in 106 depressive patients. The patients are classified according to DSM-III in two categories: minor depression (300.40, 296.82, 309.00) and major depression (296.X2, 296.X3, 296.X4). The cortisol suppression index (CSI) e.g. the ratio of pre- and postdexamethasone cortisol levels is calculated. The clinical relevance of the CSI for major depression is compared to the dexamethasone suppression test (DST). The CSI is significantly (p = 0.018) lowered in patients with major depression as compared to those with minor depression. The CSI depends (r = -0.929) on changes of the postdexamethasone cortisol levels. The DST is more useful as an external validating criterion for major depression than is the CSI. The determination of the CSI is not an asset in the diagnosis of major depression.