SAT-445 Assessing the Integrity of the Hypothalamic-Pituitary-Adrenal Axis in Patients Using Inhaled Corticosteroids

Abstract Disclosure: R. Yadav: None. S.K. Wangnoo: None. Aims: Inhaled corticosteroids (ICS) have conventionally been considered safer as compared to systemic corticosteroids. Many case reports and studies, especially in paediatric population, have shown a link between ICS use and adrenal insufficiency (AI). However similar data in adults using ICS is still scarce, and there are currently no established guidelines for screening and managing AI in this population. This study aimed to assess the prevalence of hypothalamic-pituitary-adrenal (HPA) axis suppression in adult subjects using ICS for varying indications, and to explore how factors such as ICS type, dose and duration of use correlate with AI. Methods: This pilot study recruited 106 subjects using ICS. Those who had been using ICS for less than one month, had incorrect technique or had used oral steroids in the previous 3 months were excluded. Details regarding ICS type, dose and duration were obtained. ICS doses were converted to fluticasone equivalents and classified as high (>1000 mcg/day), moderate (500-999 mcg/day), and low (<500 mcg/day). Short-term use was defined as 1 month to 1 year, and long-term use as over 1 year. All subjects underwent a Synacthen stimulation test (SST), where 250 µg of Synacthen was administered intramuscularly, followed by blood sampling after 60 minutes to measure cortisol levels. SST failure was defined by a cortisol level of less than 500 nmol/L (<18 mcg/dL) at 60 minutes, indicative of HPA axis suppression. Results: The mean age of patients in our study was 54 ± 8.2 years. 13.2% (14/106) of the study subjects failed the SST. Among those using Fluticasone, 17.9% failed SST, while 8.5% of those using Budesonide did. The risk of suppression increased with dose: 6.4% for low doses, 17.3% for moderate doses, and 28.6% for high doses. No subjects in the short-term use group had HPA axis suppression, whereas 20.2% in the long-term use group did. In the long-term group, use beyond 48 months was associated with a higher risk of HPA axis suppression. Conclusions: HPA axis suppression was found in 13.2% of ICS users. Longer duration of ICS use increased the risk of HPA axis suppression, and notably this risk was also observed at lower doses. Keywords: Inhaled Corticosteroids, Synacthen Stimulation Test, Adrenal insufficiency Presentation: Saturday, July 12, 2025