National UK audit of the short synacthen test

We present the first national audit of the Short Synacthen Test (SST), identifying the clinical, analytical and interpretative procedures adopted by 89 laboratories.

The SST has replaced the insulin stress test as the first-line test to assess adrenal insufficiency and has received considerable attention regarding its sensitivity and specificity. Concerns regarding this test include the bias of cortisol methods, cut-off values used, contraindications and the limitations of the test in diagnosing recent, mild secondary adrenal insufficiency. The audit took into consideration the protocols used by laboratories, the advice provided prior and after the SST and the analytical bias of the methods used.

A web-based questionnaire using Microsoft FrontPage(TM) was prepared to collect data from laboratories and provided drop-down lists and other form-field elements to capture additional comments. The resultant data were exported to Microsoft Excel(TM) for data clean-up and analysis.

The workloads were highly variable; however, most laboratories were in general agreement to the indications, contraindications, timing and reference ranges. In contrast, there was variability in the bias of the cortisol methods, which had not been translated to the cut-off values used by the majority of laboratories.

The audit has shown that though the preanalytical procedures were similar in most laboratories, there is a requirement to recognize the effect that method bias may have on the reference ranges and consequently on the diagnosis of adrenal insufficiency. There is a need to develop consensus guidelines, which can aid both clinicians and laboratories.