ESPE Abstracts

Introduction: Glucocorticoid replacement has been the main focus of research in congenital adrenal hyperplasia (CAH). However, few studies have focused on mineralocorticoid replacement.

Aim: Evaluation of mineralocorticoid replacement in a large cohort (n=124) with CAH recruited retrospectively over a 10-year (2010-2020) period.

Methods: We recruited 124patients (71female, 53male) with biochemically proven 21-hydroxylase deficiency CAH who required fludrocortisone and presented over a 10-year period. The types of CAH (simple-virilising [SV] and salt-wasting [SW]) were classified according to their presentation and genotypes. Hypertension was defined as systolic BP (SBP)≥95 centile or diastolic BP (DBP)≥95 centile. We referred to the Second Task Force on Blood Pressure Control in Children for 0-12months and height and age percentile chart for blood pressure for ages >12months.

Results: Mean plasma renin activity (PRA) in the first 3months of life was 44.87±47.75nmol/l/h (reference range 0.6-12nmol/l/h) and reduced to 14.9±15.97nmol/l/h after one year on treatment. A high mean dose of fludrocortisone 259.31±106.47mcg/m2/day was required during the first 3months. This was reduced to 200.13±69.87mcg/m2/day after one year, with a further reduction to 57.76±19.97mcg/m2/day. Eighty-eight patients (71%) required sodium (mean dose 6.94±2.99mmol/kg/day) during the first 3months, with a gradual reduction over time. By 2years of age, 12% still required sodium. Sixty patients met the criteria for a diagnosis of hypertension. The mean dose of fludrocortisone in the hypertensive group was higher than the non-hypertensive group (113.42±48.87mcg/m2/day c.f. 97.94±40.90mcg/m2/day; P=0.009), with a lower mean PRA in the hypertensive group (4.45±4.32nmol/l/h c.f. 13.02 ± 8.48nmol/l/h; P=0.018). We stratified the patients into SV (n=33) and SW (n=67) forms of CAH. The timing of starting fludrocortisone were not significantly different between the two (SV:1.94±3.08years c.f. SW:1.58±2.87years; P=0.448). PRA concentrations were higher in the SW group during the first year although the difference did not achieve statistical significance (35.98±366nmol/l/h c.f. 18.76±17.43nmol/l/h; P=0.243). Additionally, the dose of fludrocortisone was higher in the SW group in the first year (229.37±91.01mcg/m2/day c.f. 176.62±58.03mcg/m2/day; P=0.007). This study confirms the established practice at our centre of commencing fludrocortisone at a higher dose and titrating according to the PRA and blood pressure. Periodic assessment is also recommended by the Endocrine Society Clinical Practice Guideline 2018. The PRA should be kept within the normal range to prevent hypertension. In patients without SW, sodium should be weaned early, with a view to later reducing fludrocortisone doses if possible.