Cortisol Binding Capacity in Plasma During Anaesthesia and Surgery

The transcortin binding capacity and cortisol binding to albumin were determined before and after induction of anaesthesia and also post-operatively in 14 normal subjects undergoing major surgery. Plasma non-protein-bound (free) cortisol and total cortisol in the plasma were measured by an ultrafiltration technique and a competetive protein-binding technique, respectively. The results showed that the anaesthetics caused a decreased (0.05 < P < 0.1) binding of cortisol to albumin, while the transcortin binding capacity was unchanged. Post-operatively the mean transcortin binding capacity decreased from 24.6 to 20.4 μg cortisol per 100 ml ( P < 0.01) and the cortisol binding to albumin returned to pre-anaesthetic values. These findings could not be related to changes in the concentration of albumin, α 2 -protein and total protein in plasma.