Background: Surgical procedures are associated with activation of the hypothalamic-pituitary-adrenal axis (HPA). Studies examining HPA dynamics peri-operatively are limited and the modulating influence of peri-operatively administered glucocorticoids on that is not well established. This investigation examined alterations in HPA function and the impact of dexamethasone (DEX) administration during the peri-operative period.
Methods: We examined HPA function in 297 patients with normal function who had surgical procedures including pituitary mass resection (n = 191), craniotomy (n = 17) and other thoracic/ abdominal/ pelvic surgeries (n = 89). HPA function was assessed by frequent measurements of parameters defining adrenal function: ACTH, cortisol, DHEA and DHEA-S levels for 48 h. DEX was administered as a single dose (2-10 mg) to 30 and as multiple doses (12-36 mg) to 21 patients. The data of DEX-treated subjects within each group were similar and were combined together.
Results: Pre-operative data were similar for patients having different surgical procedures. Without DEX exposure, ACTH increased to 225 ± 100 ng/L at 2-4 h and gradually declined to baseline values by 36 h while cortisol levels peaked (39.2 ± 13.2 ug/dL) at 6-8 h declining gradually thereafter. Cortisol rise was paralleled by an equimolar increase in DHEA and a subsequent increase in DHEA-S levels. Single doses of DEX did not influence ACTH or cortisol secretion but suppressed the expected rise in DHEA and DHEA-S levels. Multiple doses of DEX suppressed ACTH and cortisol after the 15th postoperative hour and completely blocked the expected rise in DHEA and DHEA-S levels.
Conclusions: The data provide a detailed overview of HPA function in a large number of subjects who had major surgical procedures. Single and large doses of DEX did not suppress ACTH or cortisol secretion but suppressed adrenal androgen secretion. It took multiple doses of DEX to partially suppress ACTH and cortisol secretion in the peri-operative period.
Keywords: Dexamethasone; HPA function; Surgical Stress.