Background: The short Synacthen test (SST) is used primarily to diagnose adrenal insufficiency (AI), with hyponatraemia being among the commonest indications. Given the national shortage of tetracosactide and following cases of test mismanagement highlighted by our Biochemistry department, we investigated the indications, appropriate patient selection and performance of this test.
Methods: A retrospective analysis of 117 cases identified to have a SST performed between January 18 to May 18 in our Trust. We triaged the indications of the requests to four categories; Symptoms, Medications, Related conditions and Physical signs.
Results: 65% of all indications were based on a single criterion, the most common of which was hyponatraemia (54%). Only 2 cases of hyponatraemia proved to be AI and both met at least one more criterion. Overall, 88 patients had a normal response to SST and 19 patients had abnormal response. Only 2 patients with a single criterion had a positive test confirming AI. 17% of all cases were deemed as an unnecessary request, whilst in 8% the test was not performed correctly. 9% of the tests could have been avoided as they had a satisfactory morning cortisol. We observed a small number of 60 min Cortisol requests (n=5), none of which added diagnostic value.
Conclusion: The positive result yield was higher if more than one criteria were met. We conclude that it may be beneficial to perform a 9 am cortisol test prior to requesting SST. The trust is in need of guidelines for ordering SST to assist health care professionals with indications and restrictions.