THE 1-MU-G LOW-DOSE ACTH TEST FOR ASSESSMENT OF ADRENAL-FUNCTION IN GERIATRIC-PATIENTS

A commonly utilized dynamic test for evaluation of the hypothalamic-pi tuitary-adrenal (HPA) axis in the geriatric patient is the standard 25 0-mu g ACTH stimulation test. However, there are significant potential drawbacks associated with this study. In contrast, administration of 1 mu g of ACTH has been shown to be very sensitive for detecting abnor malities in the HPA axis. We therefore assessed the responses of two g roups of patients (aged 80-95 years) with no evidence of HPA disease u sing either the 1 or 250 mu g dose of ACTH (Synacthen). Twenty six pat ients received 1 mu g of ACTH (Synacthen). Seventeen others received a standard 250 mu g dose. Patients were randomly chosen. There were no significant differences in age or sex between the two groups. Plasma c ortisol was measured at 30 and 60 min after intravenous administration of either dose of ACTH. No significant statistical differences were n oted in plasma cortisol responses to 1 or 250 mu g of ACTH. We conclud e that the 1 mu g 'low dose' ACTH stimulation test can substitute for the standard 250 pg test. Clinical judgment must be used in conjunctio n with these tests in formulating therapeutic decisions. (C) 1998 Else vier Science Ireland Ltd. All rights reserved.