Endocrine Abstracts (2010) 21 P352

Assessing adrenal status in patients before and after coronary artery bypass graft surgery

Miguel Debono1, Lorcan Sheppard2, Sarah Irving2, Zoe Brookes2, John Newell-Price1, John Ross2 & Richard Ross1

1Academic Unit of Endocrinology, University of Sheffield, Sheffield, UK; 2Cardiothoracic Unit, Northern General Hospital, Sheffield, UK.

Background: Cortisol is an essential stress hormone and deficient patients suffering a systemic inflammatory response (SIR) will rapidly die if not replaced. However, controversy remains on the definition for a normal adrenal response in critically ill patients. We investigated cortisol status in patients undergoing coronary artery bypass surgery (CABG), surgery frequently associated with a SIR, varying in severity from sub-clinical, to life-threatening.

Methods: A prospective study was performed to analyse tests for adrenal insufficiency pre- and post-operatively. Prior to CABG 30 patients had a basal ACTH and a short Synacthen test (250 μg, i.v). After being weaned off cardiopulmonary bypass, patients were transferred to CICU, and had a post-op ACTH and Synacthen test around 4 h from time of induction. A 30 min cortisol post-Synacthen <550 nmol/l was taken as an abnormal response. Intensive care monitoring parameters were recorded.

Mean (95% CI)Pre-opPost-opP value
Basal cortisol (nmol/l)447 (385–509)501 (393–609)0.4
Peak cortisol post-Synacthen (nmol/l) 1048 (945–1151)730 (632–828)<0.001
Δ – cortisol post-Synacthen (nmol/l)579 (504–654)229 (170–288)< 0.001
% Change in cortisol (100% * peak-basal cortisol/basal cortisol)161 (112–210)77 (45–107)0.002
ACTH (ng/l)21 (16–26)184 (72–296)0.007
Cortisol/ACTH ratio24 (21–27)9 (6–12)<0.001

Results: Prior to surgery all patients had a normal response to Synacthen with a peak cortisol >550 nmol/l. In contrast, post-op, eight patients (26.7%) did not obtain stimulated-cortisol levels >550 nmol/l. 11/22 in those with a response to Synacthen >550 nmol/l and 5/8 in those with a response <550 nmol/l needed inotropes with a significant difference in time on inotropes (8.4 vs 21.0 h; P=0.05) and time to extubation (5.6 vs 11.7 h; P<0.001). Notwithstanding, all patients had a good final outcome from surgery.

Interpretation: The results show that up to a quarter of patients with a normal pre-operative ACTH and cortisol response to Synacthen show a raised ACTH and apparent deficient cortisol response post-operatively. In conclusion, caution needs to be taken interpreting endocrine tests post major surgery. Future studies need to focus on the ability of tests to predict outcome from steroid intervention.

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