Repeated dexamethasone suppression test during depressive illness. Normalisation of test result compared with clinical improvement.

Serial plasma cortisol concentrations were recorded under controlled conditions after an overnight dexamethasone suppression (DST) in 20 depressed patients with initially abnormal test results. The cortisol levels were related to clinical course. All 20 patients showed normalisation of hypothalamic-pituitary-adrenal (HPA) hyperactivity, a mean of 3.4 +/- 1.8 weeks before clinical recovery was achieved. In 4 clinically remitted patients the endocrine disturbance as evidenced by abnormal DST results preceded a depressive relapse. DST results did not appear to be affected by psychotropic drugs including benzodiazepines.