Endocrine Abstracts

Background: Over the last two decades, supported by two metanalyses, the low-dose Synacthen Test (LDST) has gained in popularity, with many believing it to be more sensitive than the supra-physiological Standard (250 microgram) Short Synacthen Test (SSST). The literature reveals lack of consensus about its specific clinical applications, what is considered “low-dose” and how that dose is made up.

Methods: To ascertain current UK practice, we emailed a questionnaire to all UK based BSPED members (N=257), asking for a response from one representative from each department (N=92). This was followed up, one month later, by a further request to members of departments who had not returned the questionnaire.

Results: We received 39 replies, a departmental response rate of 42.4%. Most departments (29/39, 74%) still use the 250mcg SSST and 90% (35/39) employ some form of LDST. The 1 microgram dose was used by 44% of hospitals with the other 46% using 8 different doses based on age, weight and body surface area. The dose of the SSST also varied in 18% (7/39) The indications for doing a LDST or SSST varied, as did the method of making up the low dose with 14 different ways described by 23 hospitals. The most popular method (N=5) involved mixing 0.1 ml of synacthen (25 μg) with 50 ml of normal saline, to give a concentration of 500 ng/ml and administering a dose of 1 ml/m2. Additionally we found variation in the timings of cortisol sampling and the diagnostic cut offs for adrenal insufficiency. Increased requests for synacthen tests in asthmatic children were noted by 44% respondents since the 2006 recommendations with 67% reporting detection of adrenal suppression in 10–50% of this group.

Conclusion: There is considerable variation in the methodology and application of the Synacthen test in assessing adrenal function. Is it time for standardisation?