Endocrine Abstracts

Background: To better understand current clinical practice in the treatment of children with congenital adrenal hyperplasia (CAH), a five-year observational initiative collecting longitudinal real-world data was launched in March 2022. The project focuses on patients younger than 18 years with 21-hydroxylase deficiency (21OHD) receiving care at specialist centres across the United Kingdom and Ireland, with annual data collection designed to capture evolving management patterns over time.

Methods: Data were extracted in April 2025 from the SDMregistries platform, comprising 1,291 clinic visits from 182 patients managed across 15 centres since January 2016. The number of enrolled patients per centre ranged between 1-34 (median 8). Regression analyses performed in R evaluated age- and sex-related variation in treatment regimens, biochemical markers, and World Health Organization height standard deviation scores (SDS). Glucocorticoid (GC) dosing was standardised by converting regimens into hydrocortisone (HC) equivalents adjusted for body surface area.

Results: Hydrocortisone administered three or four times daily was used in 95% of patients, while eight individuals aged 7–18 years received prednisolone. The mean GC exposure was 12.2 ± 4.0 mg HC-equivalent/m²/day, with individual averages ranging from 4.6 ± 1.2 to 22.3 ± 0.4 mg/m²/day. Marked inter-centre variability was observed, with mean dosing between 9.8-16.7 mg/m²/day. GC dose increased modestly with age (0.2 mg/m²/day annually), varied between centres, and was influenced by sex, with males receiving on average 0.8 mg/m²/day less than females. Timing of administration also differed, with six centres prescribing late-evening doses between 22:00-24:00. Fludrocortisone exposure varied widely (18–869 μg/m²/day) and differed significantly across centres (R²=0.02, P <0.01). Biochemical control was inconsistent: 17-hydroxyprogesterone levels were elevated in 42% and suppressed in 14% of visits, while androstenedione levels were elevated in 25% and suppressed in 20%. Growth patterns changed across childhood, with mean height SDS rising from −0.5 in infancy to +1.2 at about 10 years, before declining to −1.0 by 17.5 years.

Conclusions: These findings demonstrate substantial variability in therapeutic strategies for paediatric CAH across centres. Further analyses linking treatment approaches with outcomes are needed to inform best practice, support benchmarking, and improve care for children with CAH in the United Kingdom and Ireland.