Endocrine Abstracts

Background: Short synacthen test is used to assess adrenal function by injecting 250 μg of synacthen (tetracosactide) and measuring cortisol at baseline and subsequently after 30 and 60 min of the injection. In our hospital the cut-off for a normal test is a peak cortisol of 480 nmol/l or an increment of 200 or more from the baseline value.

Methodology: We reviewed the results of 50 short synacthen tests performed in our hospital within the last year to see how many patients had a normal result based on the above stated criteria. Cortisol was measured using Abbot Diagnostics.

Results: 50 patients underwent the test, 35 were females and 15 were men (mean age 56 years). Out of a total of 50 tests performed only 6 (12%) were abnormal and for all six, the peak value was <480 and the total rise in cortisol was <200.

44 patients had a normal short synacthen test result. Of these 42 (95%) patients had a 30 min cortisol of ≥480 nmol/l or an increment of 200 from the baseline. In the remaining two cases the 30 min value was <480 and the total increment in cortisol was <200. However for both these cases the 60 min result was >480.

Discussion and conclusion: The protocol for short synacthen tests and the cut-off values for normal response varies in different hospitals. In our hospital we currently check a 30 and 60 min sample after synacthen. Our audit data shows that measuring the baseline and 30 min sample will pick 95% of the positive results and 100% of the negative results. Similarly a baseline cortisol and 60 min sample will pick all the positive and all the negative results.