THE COMBINED DEXAMETHASONE CRH TEST - A REFINED LABORATORY TEST FOR PSYCHIATRIC-DISORDERS

This report summarizes our extensive experience with the application o f the DEX/CRH test to assess hypothalamic-pituitary-adrenal-system (HP A) alteration in patients with psychiatric disorders. The application of this combined dexamethasone suppression/CRH-challenge (DEX/CRH) tes t requires individuals to take 1.5 mg dexamethasone (DEX) at 23:00 h o rally the previous night. On the day of the test, 100 mu g human CRH a re administered to the subjects under study at 15:00 h intravenously a s 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 psyc hosis (SP), and 82 healthy control subjects served as the data base fo r this report. Three major conclusions can be drawn from statistical a nalysis of these data: 1. Psychiatric patients (n = 140), regardless o f diagnostic classification, release significantly more cortisol and A CTH after DEX and additional CRH in comparison with age-matched contro ls. This hormonal release pattern (DEX/CRH-test phenomenon) supports t he assumption that psychiatric patients are prone to an altered glucoc orticoid feedback regulation during the acute illness episode. This su pports the notion that the DEX/CRH-test phenomenon constitutes a neuro endocrine sign of these various disorders and emphasizes the usefulnes s of the DEX/CRH test as a laboratory test to monitor the course of th ese disorders. 2. The sensitivity of the DEX/CRH test for MDE (about 8 0%) greatly exceeds that of the standard DST (1-2 mg of DEX), which ha s been reported to average about 44% in a meta-analysis of the literat ure data; in our sample the sensitivity of the DST was about 25%. 3. T he sensitivity of the DEX/CRH test can be further increased to above 9 0% 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 a ge above 70 years. 4. By reducing the time points of blood sampling fo r 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.