Results of the ACTH stimulation test in hirsute women.

Objective: To determine the incidence of late-onset congenital adrenal hyperplasia (LOCAH) due to 21-hydroxylase deficiency among hirsute women and to evaluate the results of the ACTH stimulation test with the clinical characteristics.
Study Design: Prospective, controlled study. One hundred women with hirsutism and 14 normally cycling women without hirsutism were included in this study at the Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, Cerrahpasa School of Medicine, Istanbul University. After basal serum progesterone (P) and 17 hydroxyprogesterone (17OHP) levels were determined, an ACTH stimulation test was performed on cycle day 3-5. The same parameters were checked 30 minutes later. We estimated the 21 hydroxylase activity by calculating the change in 17OHP (17OHP 30-0) and the summed rate of the change in P and 17OHP ([P30-0] + [17OHP30-01/30 minutes). The 95th percentile for these estimates in normal women were calculated, and values above three times the 95th percentile were considered to distinguish women with LOCAH due to 21-hydroxylase deficiency.
Results: The 95th percentile for 17OHP 30-0 and (P30-0) + (17OHP30-0)/30 minutes in normal women was 1.6 and 8.9 ng/dL/min, respectively. Regarding 17OHP 30-0 values, three women with hirsutism had levels above three times the 95th percentile of these estimates, and 28 women had estimates of more than the 95th percentile but less than threefold. Seventeen of 28 women had oligomenorrhea, and all had severe hirsutism. The women with severe hirsutism and oligomenorrhea had significantly higher ACTH-stimulated serum 17OHP levels and values for 17OHP 30-0 and (P30-0 + (17OHP30-0)/30 min) than did normally cycling women.
Conclusion: The incidence of LOCAH due to 21-hydroxylase deficiency and mild 21-hydroxylase deficiency is 3% and 28%, respectively, in women with hirsutism. Clinical characteristics are not helpful in determining 21-hydroxylase deficiency. However, the incidence of 21-hydroxylase deficiency is more common among women with severe hirsutism and oligomenorrhea. The change in serum 17OHP 30-0 seems to be greater than the summed rate of change in serum 17OHP and P in the detection of 21-hydroxylase enzyme deficiency.