Background: A previous short Synacthen test (SST) audit in our hospital (2012) showed 70% of initial SST tests were normal with 9% inappropriate requests. A new pro forma was devised whereby one of four criteria (specific symptoms, medications, previous diagnosis, and physical findings) had to be satisfied to be able to undergo a SST. Additionally, we noticed that a number of patients were probably being over-diagnosed wth adrenal insufficiency (AI) based on a single 30 min cortisol estimation following SST.
Aims: To evaluate if this new pro forma helped reduce inappropriate referrals for SST and whether the added value of 60 min cortisol (rather than only 30 min) helped minimise overdiagnosis of AI.
Method: The results of this new proforma and a full SST incorporating both 30 and 60 min cortisol following SST were collected and analysed between Sept and Nov 2014.
Results: All 27 requests (100%) for SST were appropriate. 63% (17/27) of patients had an abnormal result at 30 min and 44% (12/27) at 60 min. 12 patients (44%) had both abnormal 30 and 60 min cortisol results (five on steroids, five asymptomatic, four with pituitary pathology, three hyponatremia, and one each with hypotension, T1DM and and new pigmentation). 18% (5/27) had an abnormal result at 30 min but a normal result at 60 min. 4/6 patients referred with hypotension/hyponatremia had abnormal SST result. 7/7 patients who satisfied only the symptoms criteria had a normal SST result whereas 0/5 patients who satisfied the symptoms criteria and at least one other criteria had a normal result.
Conclusion: The new pro forma has made the referral system more effective. Nearly a fifth of over diagnosis of AI can be prevented by routinely measuring serum cortisol at 60 min. By selecting symptomatic patients who satisfied at least one other criteria will also further help minimise unnecessary SSTs.