The serum cortisol:cortisone ratio in the postoperative acute-phase response

In a previous cross-sectional pilot investigation, an increase in the ratio of active cortisol to inactive cortisone in serum has been found as a general phenomenon during the acute-phase response. The aim of the present study was to further characterize this alteration of cortisol metabolism in patients undergoing elective cardiac bypass surgery.

Cortisol and cortisone were quantified by use of liquid-chromatography tandem mass spectrometry in sera that were sampled preoperatively and on the first 4 postoperative days (POD) from 16 patients undergoing aortocoronary bypass grafting (7.00 a.m.).

The median serum cortisol concentration peaked on the first POD and then decreased statistically significantly until the end of the observation period: preoperatively, 245 nmol/l (IQR 198-331); 1st POD, 532 nmol/l (IQR 409-678 ); 4th POD, 373 nmol/l (IQR 306-493); p for trend = 0.019. In contrast, the cortisol:cortisone ratio was constantly increased approximately twofold on all POD compared to preoperative sampling: preoperatively, 5.4 (IQR 5.0-7.2); 1st POD, 11.3 (IQR 9.2-13.6); 4th POD, 9.9 (IQR 7.7-11.0), with no significant trend of normalization.

Following major surgery, the substantial increase in the serum cortisol:cortisone ratio - reflecting a shift in the overall set-point of 11beta-hydroxysteroid dehydrogenase activity - is more sustained than the increase in serum cortisol; the increase in the cortisol:cortisone ratio seems to be a long-term phenomenon of the activation of the hypothalamic-pituitary-adrenocortical system by surgical stress and systemic inflammation.