Endocrine Abstracts

JOINT1402

Background: The prevalence of non-classical congenital adrenal hyperplasia (NCCAH) is estimated to be 0.1–0.2% in the Netherlands, mostly established using serum 17-hydroxyprogesterone (17-OHP) concentrations. However, it could be questioned whether this prevalence is accurate as 17-OHP measurement does not reflect optimal sensitivity and specificity for the diagnosis of NCCAH. Recently, 21-deoxycortisol (21-DOCL) has been proposed to be a valid diagnostic discriminator for both classical and non-classical CAH.

Objectives: To establish the prevalence of NCCAH in the Netherlands using serum 21-DOCL concentrations.

Methods: Steroid hormone concentrations were measured using LC–MS/MS in participants from the Netherlands Epidemiology of Obesity (NEO) study, which contained an oversampling of participants with overweight and obesity. We examined 21-DOCL concentrations in participants not using corticosteroids (3416 women and 3096 men) and used a cut-off value of 0.5 nmol/l for the diagnosis NCCAH. To rule out potential selection bias of our overweight population, prevalence rates were calculated by weighing toward distribution of body mass index in the general population.

(Preliminary) results: Based on 57 participants with a 21-DOCL concentration ≧0.5 nmol/l, the weighted prevalence was 0.94% [95% CI 0.65%–1.35%] in this population. A sub analysis showed a prevalence of 0.86% [95% CI 0.49%–1.50%] in women and 1.04% [95% CI 0.65%–1.66%] in men. When comparing the groups of participants with 21-DOCL concentrations ≧0.5 nmol/l to those with lower 21-DOCL concentrations, mean testosterone, androstenedione and 17-OHP concentrations were higher in participants with 21-DOCL concentrations ≧0.5 nmol/l.

Conclusions: The prevalence of NCCAH established based on serum 21-DOCL concentrations seems to be 5- to 10-fold higher than the previously estimated prevalence based on serum 17-OHP concentrations in the general population. This is relevant information since, in women particularly, there might be an underdiagnosis of NCCAH and possibly overdiagnosis of polycystic ovary syndrome (PCOS) due to overlapping clinical symptoms between NCCAH and PCOS.