Comparison of 1-micro g and 250-micro g corticotropin stimulation tests for the evaluation of adrenal function in patients with acquired immunodeficiency syndrome

Abstract

Many patients with acquired immunodeficiency syndrome (AIDS) have symptoms suggestive of adrenal insufficiency, but a normal 250- micro g corticotropin (ACTH) stimulation test. We compared the results of 1- micro g and standard 250- micro g ACTH stimulation tests in patients with AIDS. Each patient was studied on 2 separate days. On day 1, 1 micro g ACTH was given intravenously at 8 am after an overnight fast and serum cortisol levels were measured at baseline, and 30 and 60 minutes after ACTH infusion. On day 2, the procedure was repeated with 250- micro g ACTH. An absolute peak cortisol value of > 18 micro g/dL and an increment of 7 micro g/dL or more from baseline constituted a normal response. Among 31 patients, 16 (52%) had discrepant results: 14 (45%) had subnormal responses to 1 micro g ACTH but normal responses to 250 micro g ACTH (group 1); 2 (6%) had normal responses to 1 micro g but subnormal responses to 250 micro g (group 2) ACTH; 6 patients (19%) had concordant abnormal responses (group 3); and 9 (30%) had concordant normal responses (group 4). Eight patients of group 1 underwent a confirmatory insulin tolerance test (ITT); 4 of these patients had abnormal responses to ITT. Kappa statistic and McNemar's test were used to evaluate the data. A kappa statistic value of 0.095 and a P value less than.003 for the McNemar test indicate only random level of agreement and significant differences in the probability of positive result between the 2 ACTH tests. We conclude that discrepancies between the 1- micro g and the 250- micro g ACTH stimulation tests are common in patients with AIDS, with the likelihood of agreement with the "gold standard" ITT of only 50% for each test in our sample of patients. Larger studies are needed to further evaluate the use of these tests in patients with AIDS.