Pituitary-adrenal responses following major abdominal surgery.

Objective: Perioperative pituitary-adrenal responses after major abdominal surgery have not been well characterized. The aim of the present study was to further clarify perioperative pituitary-adrenal responses.

Design: Thirty-six patients (20 men), aged 68+/-10 years (mean+/-SD), undergoing major abdominal operations were studied. Total cortisol (TC), adrenocorticotropic hormone (ACTH), corticosteroid-binding globulin (CBG), dehydroepiandrosterone (DHEA) and its sulphate (DHEAS) were measured preoperatively (PreOp), on the day of surgery (DoS) and on the first and second postoperative days (PoD1 and PoD2). The free cortisol index (FCI) was also calculated. In addition, patients underwent a low-dose (1 mug) ACTH stimulation test, preoperatively and on PoD1, to assess adrenal responsiveness to ACTH.

Results: TC, FCI, ACTH and DHEA were increased, while DHEAS and CBG declined on DoS compared to PreOp levels. On PoD1, plasma ACTH was lower compared to the preoperative levels, FCI remained elevated, DHEA, DHEAS and TC returned to their baseline values, while CBG was still low. On PoD2, ACTH and CBG were low and FCI returned to its PreOp levels. Postoperatively, stimulated FCI was higher compared to the PreOp value.

Conclusion: At an early phase following major surgery, elevated cortisol is associated with high ACTH. Despite HPA activation and a concomitant rise in DHEA levels, DHEAS declines. Later on, a remarkable dissociation between ACTH (low) and cortisol (high) is observed, which is attributed, at least in part, to increased adrenal responsiveness to ACTH.