Diagnosis of late-onset congenital adrenal hyperplasia in clinical practice: current evaluation

Aim of the study was to investigate the need to perform the adrenocorticotropic hormone (ACTH) stimulation test by recognizing the importance of a second look at basal serum 17-alpha hydroxyprogesterone (17-OHP) levels and calculating new serum 17-OHP cut-off level.

A total of 142 patients who had hyperandrogenism symptoms and had basal serum 17-OHP levels of higher than 1.3 ng/mL were scheduled to have an ACTH stimulation test performed. Prior to ACTH stimulation, 17-OHP levels were recorded and as second-look levels.

Patients were divided to two groups, late-onset congenital adrenal hyperplasia (LOCAH) (25/142), non-LOCAH (117/142). There were statistically significant results related to cycle length and menstrual irregularity between two groups (P=0.042, P=0.041, respectively). In the LOCAH group, basal serum 17 OHP levels were higher than non-LOCAH (P=0.001). When basal serum 17-OHP levels were measured a second time, the need for performing the ACTH stimulation test was decreased. According to cut-off levels of 1.3 ng/mL, 100% of patients needing to take the second serum 17-OHP decreased to 83.1%, a cut-off level of 2 ng/mL decreased numbers from 74.65% to 35.92% and for 2.25 ng/mL 58.42% of patients was decreased to 26.77%. In this study we established 2.25 ng/ml is a superior cut-off level for 17-OHP, its sensitivity is 84% and specifity is 50.4%.

The incidence of LOCAH is 1.35% among the patients with hyperandrogenism symptoms. We found a single measurement of serum 17-OHP level can be unreliable. Second 17-OHP test reduces the need of performing the ACTH stimulation test by approximately 30%.