Endocrine Abstracts

17α-hydroxyprogesterone (17OHP) is currently used as a diagnostic parameter in children and young adults when a milder form of congenital adrenal hyperplasia (CAH, late-onset) is suspected. A basal serum level of 17OHP (2 ng/ml; 6.0 nmol/l, respectively) has been discussed as cut-off for suspected late-onset disease. We analysed 17OHP in a cohort of children and adolescents without CAH and in confirmed CAH patients to define reference ranges for these age groups. For the analysis of 17OHP, we used a novel automated immunoassay in 506 anonymized samples from children and adolescents with a previous exclusion of CAH by conventional hormone measurement. 302 girls and 204 boys in two age groups from 1–11 and 12–18 years were included. In a subgroup of 49 probands, follow-up samples within one year were available, as well as in 17 out of initially 38 children with genetically confirmed CAH. In prepubertal children at the age of 1–11 years, mean 17OHP serum concentrations were 0.99 ng/ml ±0.86 (STD) (reference limits 0.31–4.62) for girls and 0.85±0.59 (reference limits 0.31–2.60) for boys, which was not statistically different (P=0.852). There was also no difference in mean 17OHP serum concentrations at the age of 12–18 years between female 1.39±0.70 (reference limits 0.37–3.26) and male adolescents 1.38±0.67 (reference limits 0.32–2.93) (P=0.95). Repeated measurements in follow-up samples showed a mean coefficient of variation (CV) for non-CAH samples of 14.2 and 20.8% in CAH patient samples. In our study, baseline 17OHP was a useful marker for the exclusion of late-onset CAH in the majority of samples. Based on the established reference ranges, an overlap with confirmed CAH patients was very small. In suspicious cases, additional hormonal tests as well as stimulation tests of 17OHP have been defined as the standard of late-onset CAH diagnosis and therapy monitoring.