Endocrine Abstracts

The short synacthen test (SST) is the most commonly performed investigation to assess adrenal function. We retrospectively audited the SSTs performed by the endocrine department in University Hospital Limerick between 2022 and 2024. The SST was performed as per our hospital protocol. A post-adrenocorticotropic hormone (ACTH) cortisol response of 450 nmol/l (using Roche Elecsys Cortisol III immunoassay) at any time point was considered adequate to rule out adrenal insufficiency. The data were analysed to ascertain the proportion of patients who achieved this level at 30 and/or 60 min. Patients taking the oral contraceptive pill were excluded from analysis. All tests were performed in the morning between 9.00 and 11.00. Eighty patients (61 female) underwent a short synacthen test in the day ward in this time. The Median age was 49 years, range 17-89 years. The most common indication was patients on long term steroids, receiving prednisolone treatment (n = 23). 61/80 (76.25%) patients passed the short synacthen test on the 30 minute sample. The median baseline cortisol in the patients who passed the short synacthen test was 319 nmol/l (range: 107-1068). A further 5 patients (6.25%) passed the short synacthen test on the 60 minute sample but not the 30 minute. The median 30 minute cortisol for these patients was 413 nmol/l (403-430 nmol/l). The protocol for short synacthen tests and the cut-off values for normal response varies in different hospitals. In our centre, the SST has previously been performed with both the 30 minute and 60 minute samples. However, using the 30 min cortisol sample post-Synacthen administration alone identifies clinically relevant adrenal insufficiency in the majority of cases. Sampling at 60 minutes should be reserved for patients who have borderline cortisol response at the 30 minute sample.