Endocrine Abstracts

Background: 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH) is characterised by cortisol deficiency, androgen excess, varying degrees of virilisation and salt-wasting. CAH management involves replacement therapy with hydrocortisone, and, often, fludrocortisone. High levels of androgens cause the advancement of bone age (BA) with the potential to increase bone mineralisation. Hydrocortisone therapy on the contrary can contribute to reducing bone mineralisation. Patients with CAH have an increased prevalence of fractures which may be related to bone mineralisation.

Objectives: To assess whether bone mineralisation in paediatric CAH patients is significantly different to the general population and to determine factors contributing to bone mineralisation.

Methods: Bone health index (BHI) measured using BoneXpert provides observer-independent information on cortical thickness and mineralisation based on hand X-ray and correlates with bone mineralisation measured by Dual-energy-X-ray-absorptiometry. 141 (74 female, 67 male, 0.32 – 17.55 years) records of CAH patients at Royal Manchester Children’s Hospital were accessed and data collected for z-scores of bone age (BA), bone health index (BHI), height, weight, body mass index (BMI), adrenal androgens and renin; hydrocortisone (HC, mg/m2/day) and fludrocortisone (FC, mg/m2/day) doses were also collected. One sample t-tests were undertaken for variance in growth parameters, BA and BHI standard deviation scores (SDS) compared to the normal population; correlation was assessed between BA SDS, BHI SDS, and adrenal androgens, renin, HC, and FC doses.

Results: BHI is significantly reduced (mean -0.5, p<0.001) while BA is significantly advanced (mean 2.6, p<0.001). No correlation was found between BHI and HC dose, FC dose, adrenal androgens (except for negative correlation between BHI and DHEAS) (Table).

Conclusion: Bone mineralisation as assessed by BHI, in our cohort, is reduced and this may contribute to increased prevalence of fractures in CAH. This deficit appears to be independent of adrenal androgen levels and HC dosing.