Endocrine Abstracts

Introduction: Glucocorticoids can cause adrenal insufficiency through suppression of the hypothalamic-pituitary adrenal axis. Consensus on optimal glucocorticoid weaning or timing for dynamic function testing is lacking

Objective: To investigate factors affecting short synacthen test (SST) response following high-dose corticosteroid therapy in children.

Methods: This retrospective cohort study reviewed 17 patients referred to Evelina London Children’s Hospital’s Paediatric Endocrine team for adrenal sufficiency testing between April 2022 and July 2023. Adequate response on SST was defined by peak cortisol levels ≥420 nmol/l. Data on demographics, anthropometrics, glucocorticoid treatment, and SST results were analysed on 16 patients, excluding one patient with incomplete documentation.

Results: There were no significant differences in baseline characteristics including age, gender, body surface area, peak dose, and cumulative dose between adequate (n=7) and inadequate (n=9) initial SSTs.

• Prednisolone was used more commonly at initial SST (n=12) compared to hydrocortisone (n=4) with no significant difference in inadequate response rate (OR, 0.33, CI 0.03-4.19)

• 50% (n = 8) of initial SSTs were performed at supra-physiological hydrocortisone dose equivalents (HDEs) ≥10 mg/m²/day.

• HDEs between 10.1-15.0 mg/m²/day (n=7) could represent prednisolone use where dosage manipulation is less graduated. There was no statistically significant difference in inadequate response rate in this group vs testing at HDEs ≤10 mg/m²/day (OR, 0.45, CI, 0.05-3.57)

• A longer mean time from steroid initiation to initial SST was observed adequate initial SSTs compared to inadequate initial SSTs (364 days vs 168 days, respectively; P = 0.073).Analysing all SSTs performed including repeat tests following inadequate initial SSTs (n=27) found:

• SSTs performed ≥30 days since reaching <15 mg/m²/day HDE had a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 30% for adequate response. The threshold of <15 mg/m²/day was used to avoid excluding a significant portion of test results.

• SSTs performed ≥110 days post-steroid initiation showed a PPV of 93.75% and an NPV of 30% for adequate response.

Conclusion: Slower steroid tapering, with lower doses for extended periods, predicts better adrenal response. Research with larger cohorts is needed to validate these findings.

Keywords: glucocorticoids, adrenal insufficiency, synacthen test, paediatric endocrinology