Endocrine Abstracts

Aim: The latest NICE Guidelines [NG243] on adrenal insufficiency recommends 9am cortisol >300nmol/l as a screening test to rule out adrenal insufficiency. The aim of our study was to assess the utility of using random cortisol in avoiding the need for short Synacthen tests (SST), and its impact on easing constraints on metabolic unit in a secondary care setting.

Methods: Clinical data on all patients who have undergone SST, at any time during the day, over a 12-month period was collected. Patients undergoing 6-week post-operative assessment after pituitary surgery were excluded (n = 37). Baseline cortisol, done as part of SST, was used as ‘random’ cortisol for analysis. A 30-min cortisol of ≥500nmol/l, usually with increment of ≥200nmol/l from baseline, was considered an adequate response in the SST.

Results: n = 334. 280 patients had an adequate response in the SST, with 259 having both 30-min cortisol ≥500nmol/l and increment of ≥200nmol/l from baseline. Baseline cortisol ranged between 85 and 1312nmol/l in this cohort. 181 of the 334 patients had baseline cortisol >300nmol/l, showing 54% of SST could be avoided by using NICE guidelines. Among the 54 patients with inadequate SST response, the baseline cortisol ranged between <50 to 288nmol/l. This conforms to the NICE cut-off of >300nmol/l to safely avoid conducting SST. 72% (n = 39) were secondary to glucocorticoid withdrawal, 15% (n = 8) related to pituitary issues and 6% (n = 3) for Addison’s disease.

Conclusion: This study shows that random cortisol could help to predict an adequate response to SST in the low/moderate risk patients in secondary care. The 9am cortisol, as proposed by NICE, which would be more reliable than random cortisol, should be integrated into care pathways, with appropriate adjustment based on calibration for local assays. This initial screening is even more pertinent with increasing referrals and indications for assessing cortisol axis.