The combined dexamethasone/CRH test: a refined laboratory test for psychiatric disorders

This report summarizes our extensive experience with the application of the DEX/CRH test to assess hypothalamic-pituitary-adrenal-system (HPA) alteration in patients with psychiatric disorders. The application of this combined dexamethasone suppression/CRH-challenge (DEX/CRH) test requires individuals to take 1.5 mg dexamethasone (DEX) at 23:00 h orally the previous night. On the day of the test, 100 micrograms human CRH are administered to the subjects under study at 15:00 h intravenously as a bolus, and blood samples for the determination of plasma cortisol and ACTH are drawn every 15 min from 14:00 h to 18:00 h. DEX/CRH-test results from 96 patients with major depression (MDE), 11 with a manic episode (MA), 9 with panic disorder (PD), 24 with a schizophrenic psychosis (SP), and 82 healthy control subjects served as the data base for this report. Three major conclusions can be drawn from statistical analysis of these data: 1. Psychiatric patients (n = 140), regardless of diagnostic classification, release significantly more cortisol and ACTH after DEX and additional CRH in comparison with age-matched controls. This hormonal release pattern (DEX CRH-test phenomenon) supports the assumption that psychiatric patients are prone to an altered glucocorticoid feedback regulation during the acute illness episode. This supports the notion that the DEX/CRH-test phenomenon constitutes a neuroendocrine sign of these various disorders and emphasizes the usefulness of the DEX/CRH test as a laboratory test to monitor the course of these disorders. 2. The sensitivity of the DEX/CRH test for MDE (about 80%) greatly exceeds that of the standard DST (1-2 mg of DEX), which has been reported to average about 44% in a meta-analysis of the literature data; in our sample the sensitivity of the DST was about 25%. 3. The sensitivity of the DEX/CRH test can be further increased to above 90% if subjects are clustered into four different age ranges: age < 35 years, age between 35 and 50 years, age between 50 and 70 years, and age above 70 years. 4. By reducing the time points of blood sampling for ACTH and cortisol to as few as five (15:00, 15:30, 15:45, 16:00, and 16:15 h), the DEX/CRH-test procedure becomes more convenient and more easily applicable without reducing its sensitivity.