Endocrine Abstracts

Introduction: Short synacthen® test (SST) is widely used to assess adrenal function. Controversy remains concerning sample timing and diagnostic cut-offs.

Methods: A retrospective analysis of SST results over 48-month period (1/1/2020 - 31/12/2023) was undertaken. Our protocol involves sampling cortisol at times 0, 30 and 60 minutes post Synacthen® 250 mg IM. Normal SST response was peak cortisol (assayed using Abbott Architect i2000) concentration of ≥470 nmol/l at 30 or 60 minutes. The aim of this audit was to assess protocol adherence, and to determine test outcomes and referral patterns.

Results: Of 343 total SSTs, 26 were excluded due to missing time-point data. Of 317 SSTs analysed, 51.1% were female. Median age in females was 53 years (range 17-90 years); in males 59 years (range 17-94 years). 257 tests (81.1%) occurred before 12pm, 60 tests (18.9%) occurred after 12pm. Test requests per speciality were Endocrinology 135 tests (42.6%), Medicine 162 tests (51.1%), of which Oncology had the highest number and Surgery 17 tests (5.3%). Indications for testing were collapse (12.3%), fatigue (11.6%), postural hypotension (9.4%), low AM cortisol (8.2%) and hyponatraemia (6.6%). Of 317 SSTs, 234 (73.8%) passed. Of the 83 (26.2%) who failed, 100% had cortisol level of <470 nmol/l at both 30 and 60 mins. Median cortisol at 60 mins was 314.8 nmol/l (range <28-467 nmol/l). No patient passed at 30 mins and failed at 60 mins. 47 patients (14.8%) achieved a pass at 60 mins but failed at 30 mins. Of those patients, seven were re-tested with four subsequently passing. One patient had no clinical data available.

Conclusion: The majority of tests were performed correctly as per protocol. Further data interrogation is required to investigate the utility and retention of the 60 min sample timing in our protocol.