Comparison of 1-μg and 250-μg 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-μg corticotropin (ACTH) stimulation test. We compared the results of 1-μg and standard 250-μg ACTH stimulation tests in patients with AIDS. Each patient was studied on 2 separate days. On day 1, 1 μg 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-μg ACTH. An absolute peak cortisol value of > 18 μg/dL and an increment of 7 μg/dL or more from baseline constituted a normal response. Among 31 patients, 16 (52%) had discrepant results: 14 (45%) had subnormal responses to 1 μg ACTH but normal responses to 250 μg ACTH (group 1); 2 (6%) had normal responses to 1 μg but subnormal responses to 250 μg (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-μg and the 250-μg 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. © 2003 Elsevier Inc. All rights reserved.