The Majority of Inpatient Short Synacthen Tests Are Performed Incorrectly, Due to Imprecise Timing, Incorrect Sampling and Failure to Interrupt Steroid Administration

Abstract

Introduction: The short synacthen test (SST) is commonly used to assess adrenal function. Accurate timing and appropriate holding of exogenous steroids are essential to ensure correct interpretation of results. Aims & Methods: We reviewed all SSTs performed on inpatients in our hospital over a 1-year period, in order to determine accuracy of testing. Results: 42 patients (Male 15, Female 27), with mean age 68 years (range 43–90), underwent SST. The majority (39/42; 93%) of tests were requested by internal medicine physicians. The indications for testing were; suspected adrenal insufficiency (18), HPA axis suppression (9), fatigue (7), hyponatremia (5), suspected pituitary disease (2) and vomiting (1). 7 (44%) of the 16 patients taking steroids did not have medication appropriately held. 31 (74%) patients did not have serum ACTH measured prior to the test. 28 (66%) tests were not started at the correct time. Only 10 (24%) of the 30 minute samples were completed within the 25-35min sample window. The mean time between the 0min and 30min samples was 42mins (median 62mins; range 0-209mins). 12 (29%) tests involved an unnecessary 60min sample. 8 (19%) tests had no interpretation of results documented in the medical notes. 4 (10%) patients underwent repeat testing, necessitated by an incorrect first test. Discussion: The vast majority of inpatient SSTs (33/42;79%) were performed suboptimally, with the most common errors pertaining to incorrect timing of the test, inaccurate sampling and inappropriate pre-test steroid administration. Considering these errors, some results may have been interpreted incorrectly. Repeat tests were recognised as required in 10% of patients, with associated inconvenience, cost and discomfort. Improved training and guidelines for performing SSTs should be available to hospital staff to ensure more accurate application of the test.