IMPACT OF OVERNIGHT DEXAMETHASONE SUPPRESSION ON THE ADRENAL ANDROGENRESPONSE TO AN ORAL GLUCOSE-TOLERANCE TEST IN WOMEN WITH AND WITHOUT POLYCYSTIC-OVARY-SYNDROME

In order to test the hypothesis that adrenocortical over-activity, pos sibly related to the stress of testing, may impact on the measurement of circulating androgen concentrations during glucose-induced hyperins ulinaemia, we prospectively screened 10 patients with the polycystic o vary syndrome (PCOS) and nine healthy control women with an oral gluco se tolerance test (OGTT), before and after the administration of dexam ethasone, Blood sampling was performed at 0, 30, 60, 90, and 120 min f ollowing the oral ingestion of 75 g of glucose, before and after the a dministration of 1.0 mg dexamethasone on the evening prior to testing, Total and free testosterone, androstenedione, dehydroepiandrosterone (DHEA), DHEA sulphate (DHEAS), cortisol, glucose and insulin were asse ssed during the 2 h OGTT. Women with PCOS had increased basal concentr ations of free testosterone, total testosterone, androstenedione, and insulin compared to control women, In women with PCOS an acute decline in circulating concentrations of DHEAS occurred during the OGTT, In P COS women there were no changes in other ovarian or adrenal androgens during OGTT before or following dexamethasone administration, In contr ol women DHEA concentrations declined during the OGTT, Following overn ight dexamethasone suppression in control women, circulating concentra tions of DHEAS and testosterone also declined, It is concluded that: ( i) in PCOS women only the concentration of circulating DHEAS decreased during glucose-induced hyperinsulinaemia and dexamethasone administra tion did not further alter androgen responses to an OGTT; (ii) it is p ossible that, in these hyperandrogenic patients, the insulin-related s uppression of adrenocortical testosterone and DHEA is negated by their much greater ovarian secretion of these androgens; (iii) in control w omen DHEA concentrations acutely declined during the OGTT and the admi nistration of dexamethasone resulted in the acute decline of DHEA, DHE AS, and testosterone; (iv) it appears that the stress related to testi ng impacts on the androgen response to OGTT, at least in healthy women .