Precocious Pubarche: Distinguishing Late-Onset Congenital Adrenal Hyperplasia from Premature Adrenarche

Context: Because precocious pubarche (PP) reveals late-onset congenital adrenal hyperplasia (LO-CAH) in 5 to 20% of cases, an adrenal stimulation test is recommended in all patients presenting with it. This test is stressful and expensive, and results are normal in more than 80% of cases. Objective: Our objective was to identify clinical and plasma predictors of LO-CAH among patients presenting with PP. Design, Setting, and Patients: We conducted a retrospective cohort study that included all patients seen for PP at our hospital between 1999 and 2006 (n = 238). All had undergone an ACTH test. Main Outcome Measure: LO-CAH was defined by a post-ACTH 17-hydroxyprogesterone (17-OHP) plasma level greater than 10 ng/ml and confirmed by mutational analysis of the CYP21 gene. The association of standard clinical and laboratory indicators with LO-CAH was assessed. Results: Ten (4%) of 238 patients had LO-CAH. Basal 17-OHP, Delta 4-androstenedione, and testosterone plasma levels were significantly higher in these patients. A 2-ng/ml threshold for basal 17-OHP plasma levels offered 100% (95% CI, 69-100) sensitivity for the diagnosis of LO-CAH and 99% (95% CI, 96-100) specificity. Conclusion: We identified three plasma predictors of LO-CAH in patients presenting with PP. A selective strategy based on a 2-ng/ml basal 17-OHP plasma level threshold would have safely avoided 99% of the unnecessary ACTH tests among our patients. (J Clin Endocrinol Metab 94: 2835-2840, 2009)