OVERDIAGNOSIS OF 21-HYDROXYLASE LATE-ONSET CONGENITAL ADRENAL-HYPERPLASIA - CORRELATION OF CORTICOTROPIN TEST AND HUMAN-LEUKOCYTE ANTIGEN TYPING

Objective: To evaluate the reliability of the ACTH test as a means for detection of late onset congenital adrenal hyperplasia (CAH) and disc riminating it from polycystic ovary syndrome (PCOS), by repeating the test after 6 months of cyproterone acetate and ethinyl E(2) treatment. Design: Follow-up comparison study. Setting: Reproductive Endocrinolo gy in an university tertiary center. Patients: Thirty-one young women with hirsutism, oligoamenorrhea, and acne, 21 of them detected as late onset CAH, and 10 as non-late onset CAH (PCOS). Intervention: Cyprote rone acetate and ethinyl E(2) treatment for greater than or equal to 6 months. The ACTH test, before and after 6 months of cyproterone aceta te + ethinyl E(2) treatment, and human leukocyte antigen (HLA) typing. Main Outcome Measure: The ACTH test interpretation correlated to HLA typing. Results: By repeating the ACTH stimulation test in the 31 wome n (after cyproterone acetate + ethinyl E(2) administration), we found a diminution in the rate of accumulation of 17 alpha-hydroxyprogestero ne (Delta 17-OHP) + P, in all 21-hydroxylase late onset CAH cases. As a result of treatment with cyproterone acetate + ethinyl E(2), a decre ase in the accumulation rate of 17-OHP + P, below the discriminative v alue for late onset CAH (6.5 ng/dL per minute), was noted among 12 of 21 women defined primarily as late onset CAH. Among the nine other wom en, a decrease in the accumulation rate of 17-OHP + P was noted, howev er not <6.5 ng/dL per minute. Conclusions: The interpretation of Delta 17-OHP + P for the diagnosis of late onset CAH may be too sensitive a s to the correct clinical diagnosis of late onset CAH. By repeating th e ACTH test after 6 months of treatment with cyproterone acetate + eth inyl E(2), specificity and accuracy may be improved.