Clinical Variability in Congenital Adrenal Hyperplasia: A Distinct Subgroup with a Low Glucocorticoid Dose Requirement.

Introduction: Some children with classic congenital adrenal hyperplasia (CAH) achieve excellent control on very low glucocorticoid doses. We aimed to characterize these patients and assess the timing of their low-dose requirements.

Methods: We reviewed charts of patients with salt-wasting CAH due to 21-hydroxylase deficiency, defining low-dose glucocorticoid as <10 mg/m2/day. Demographic and growth data were compared with a matched group on standard doses.

Results: Among 154 patients with CAH, 14 (9%) required low-dose glucocorticoid therapy (<10 mg/m2/day), including 8 boys (57%) and 6 girls (43%). The average age at treatment initiation was 2.1 years, comparable to a matched group of 23 patients (48% boys). The low-dose group received 8.8 ± 1.2 mg/m2/day versus 14.9 ± 3.9 mg/m2/day in the matched group (p < 0.001), with similar fludrocortisone doses (0.1 ± 0.05 mg). No differences were observed in weight, height, or height velocity. Of the 14 patients on low-dose treatment, 3 experienced an increase in their glucocorticoid dose requirement above 10 mg/m2/day at ages 10.3, 10.8, and 8.5 years after being on 6.3-9.8 mg/m2/day for 6.4-8.5 years. The remaining 11 patients are currently on 5.89-10 mg/m2/day with a duration on low-dose therapy ranging from 0.48 to 8.65 years.

Conclusion: Our findings highlight a subgroup of patients with 21-hydroxylase deficiency who achieve good control on low glucocorticoid doses from early childhood. The factors underlying this and the transient need for low doses in some remain unclear.