Aims: Short synacthen test (SST) is commonly used to diagnose adrenal insufficiency (AI), and with serum ACTH, can help differentiate between primary and secondary AI. The aim of this audit was to evaluate the clinical appropriateness of SST in our endocrine unit.
Methods: We looked at all SSTs performed between August 2012 and August 2013. Relevant clinical information was collected from patient notes and database. A SST was considered inappropriate if no reason was provided for the test or the patients clinical history did not vaguely support the need for a SST.
Results: 68 patients satisfied the study criteria and a total of 79 SSTs were conducted; nine patients had at least one repeat SST during this period (54% females, 46% males mean age 46 years). Ethnicity: 25 - White-British, remainder Asian, Black, Others and mixed ethnicity. The most common indication for a SST referral was suspected secondary AI (25: 17 pituitary, eight exogenous steroid), followed by non specific symptom complex (NSSC) of fatigue/weight loss/hypotension/dizziness (23), hyponatremia (5), primary AI (2) and other causes (13).
24/79 (30%) SSTs were abnormal 10, 8, 9 and 3% of the abnormal SST results were due to pituitary problems (8: empty sella 2, prolactinoma 2, pituitary adenoma 4), exogenous steroid (6), NSSC (7) and others (3: 1 each of primary AI, hyponatremia and idiopathic) respectively. 7/79 (9%) SSTs were deemed inappropriate.
Conclusion: While the most common indication for a SST was suspected secondary AI (32%), 70% of initial SSTs were found to be normal. Furthermore, 9% of SST referrals were considered inappropriate. There is thus a discrepancy between clinical suspicion of AI and actual adrenal function. We would suggest careful selection of patients for SST consideration (suspected secondary AI and NSSC) so as to minimize future unnecessary SSTs in the vast majority.