Plasma clearance of cortisol as a function of plasma cortisol levels in normal and obese persons and in patients with uraemia or cirrhosis of the liver.

Plasma cortisol levels in 2 normal persons, 2 obese persons, 2 uraemic patients, and 2 patients with cirrhosis of the liver were raised in 4 steps by a combination of iv priming doses and continuous infusions of cortisol. Plasma cortisol levels and transcortin binding were measured as well as plasma clearance rates of labelled and unlabelled cortisol during each of the 5 experimental periods. Plasma cortisol levels increased less and plasma clearance rates of labelled and unlabelled cortisol increased more in obese persons than in normal persons; in patients with disturbed metabolism of cortisol (uraemia, cirrhosis of the liver) the reverse is true. Plasma clearance rates of free cortisol were calculated and differed from an estimated hepatic plasma flow of 0.7 1/min under certain conditions. Since free cortisol is metabolized faster than transcortin-bound cortisol, increasing plasma clearance rates of cortisol are probably due to increasing ratios free/bound cortisol when total plasma cortisol levels are raised. Low plasma clearance rates of cortisol in uraemia and cirrhosis of the liver are thought to be due to endproduct inhibition, respectively reduced liver cell mass.