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Abstract
Several investigators have suggested that the adrenal response to an intravenous bolus dose of ACTH accurately predicts the integrity of the HPA axis, without causing the side effects attendant on insulin-induced hypoglycemia or administration of metyrapone or pyrogen.1 2 3 However, ACTH stimulation does not directly measure hypothalamic or pituitary responsiveness, and thus it carries the theoretical risk of diagnostic error in patients with pituitary or hypothalamic disease. Discussion Discrepancies between the serum cortisol response to insulin-induced hypoglycemia and more prolonged exogenous ACTH stimulation tests have been reported in the past.7 8 9 10 11 However, Lindholm et al.3 and others2 have subsequently shown a close correlation between the insulin-tolerance test and ACTH responsiveness by using a short ACTH test consisting of an intravenous bolus dose of cosyntropin. [...]using a bolus dose of cosyntropin for the ACTH test does not prevent the occurrence of falsely normal test results that have been seen with prolonged ACTH stimulation. Wynn V. The plasma sugar, free fatty acid, cortisol, and growth hormone response to insulin, and the comparison of this procedure with other tests of pituitary and adrenal function.