BLUNTED DEXAMETHASONE-INDUCED GROWTH-HORMONE RESPONSES IN ACUTE MANIA

Dynamic endocrine testing using a variety of probes has revealed abnor malities of the somatotropic axis in bipolar mania. In health, acute a dministration of dexamethasone (DEX) results in the secretion of growt h hormone (GH) by possibly inhibiting somatostatin tone. We elected to determine DEX/GH responses in acute mania. Eight male bipolar manics were compared with eight age-matched healthy volunteers. Four milligra ms of oral DEX was administered at 0900h (time 0 min) and plasma sampl es for GH were taken at +60, +180, +240 and +300 min. Baseline samples for GH and cortisol were taken at -15 min and 0 min. Patients had hig her basal cortisol levels (391.6 +/- 89.4 nmol/l) as opposed to contro ls (138.0 +/- 13.2 nmol/l) (paired t-test, t=4.68, df=6, p < .0004). T he mean (+/- SD) Delta GH (calculated as the maximum GH level relative to baseline) in the manic patients was 0.7 +/- 0.8 ng/ml and in the h ealthy controls was 9.2 +/- 4.3 ng/ml (paired t-test, t=-0.589, df=6, p < .0001). In conclusion, patients with bipolar mania had lower DEX-i nduced GH responses in comparison to controls. (C) Elsevier Science Lt d.