Endocrine Abstracts

Introduction: Short Synacthen Tests (SSTs) are the gold standard for diagnosis of Adrenal Insufficiency. An early morning cortisol may be an acceptable alternative. We wished to establish current local practice in testing and what lessons could be learned. Clyde uses the Architect Cortisol Assay – adequate response taken as post-Synacthen cortisol of ≥430nmol/l.

Methods: We aimed to gather data on ≥100 SSTs and this took 11 weeks (20/05/19 - 04/08/19). We performed a retrospective analysis on these cases.

Results: • A serum cortisol level alone was measured in 122 patients, 23 had a cortisol level followed by a SST and 78 had a SST only.

• Five patients were newly diagnosed with Adrenal Insufficiency.

• 80 patients had a cortisol level < 430nmol/l but no further action was taken.

• Eight patients with a cortisol level ≥ 430nmol/l proceeded to SST.

• 79% (56) of random cortisol levels taken 10:00-03:59 were < 430nmol/l, compared to 51% (39) of early morning samples taken 04:00-09:59.

• 12 patients had cortisol testing without withholding corticosteroid treatment.

• All patients with a pre-Synacthen cortisol of ≥336nmol/l mounted a satisfactory response to Synacthen.

Conclusions: Random cortisol levels are frequently used in our hospitals to test for Adrenal Insufficiency. Our results reveal wide variation in use and interpretation. This may be due to a variety of factors including unfamiliarity, the variety of guidelines and assays staff have used in other institutions, and clinical judgement. A random cortisol is easier to perform than SSTs; we suspect that the tests were performed at a lower threshold of suspicion which may affect interpretation.

Based on these results we would recommend:

1. Avoid checking random cortisol levels outwith 04:00-10:00 (unless suspicious of acute adrenal crisis).

2. Withhold exogenous corticosteroid before testing.

3. For inpatients : check early morning cortisol and if < 336nmol/l proceed to SST. For outpatients : proceed straight to SST.