Endocrine Abstracts

Introduction: The clinical utility of cortisol response to the Glucagon Stimulation Test (GST) in children remains unclear, with conflicting evidence. Concerned about potential overuse of the Synacthen Stimulation Test (SST), we evaluated cortisol levels during GST and assessed the impact of clinical factors such as age, sex, pubertal status, and BMI.

Methods: A retrospective chart review was conducted on children who underwent GST for short stature between January 2024 and February 2025 at Evelina Children’s Hospital, London. Demographic and anthropometric data were collected. Cortisol and GH responses to GST, and SST results where available, were analysed using non-parametric tests.

Results: 105 children underwent GST during the study period. 13 (12.3%) had suboptimal cortisol responses; 12 (92.3%) passed subsequent SST, and 1 on steroids had SST deferred. Cortisol peaked at 120’ in 8 (7.5%), 150’ in 26 (24.7%), and 180’ in 67 (63.8%); mean peak was 592 nmol/l. Among those with suboptimal cortisol, mean age was 14.5 years, 12 (92.3%) were male, 9 (69.2%) pubertal, and 5 (38.4%) overweight/obese. Five also had suboptimal GH responses, and one failed a second growth hormone stimulation test with arginine. Younger children had significantly higher cortisol levels; higher BMI (p< 0.001) was associated with lower cortisol. SST peaks were consistently higher than GST peaks. (Figure-1)

Conclusion: Our findings support that although both GST and SST are viable tools for assessing adrenal reserve in children, SST consistently produces higher peak cortisol responses than GST. Additionally, GST results are influenced by age and BMI, with older and overweight children demonstrating lower cortisol, potentially leading to false positives. In contrast, SST gives a more robust, reliable assessment with well established cut offs. Therefore, while GST can serve as an alternative, SST remains the preferred method for accurate pediatric adrenal evaluation.

Reference: 1. Arlien-Søborg MC, Radovick S, Boguszewski MCS, et al. Consensus and controversies about diagnosing GH deficiency: a Delphi survey by the GH research society. Pituitary. 2025;28(3):57.2. Borghammar C, Svensson J, Tidblad A, Elfving M. Sex and age differences in cortisol levels during glucagon stimulation test in children. BMC Pediatr. 2025;25(1):440.