PROTEIN BINDING OF CORTISOL IN HEALTH AND IN PREGNANCY

Abstract

SUMMARY The binding of plasma cortisol to transcortin at 37° c was studied in normal men and in non-pregnant and pregnant women. The mean concentrations of transcortin were 8, 11·5 and 14 × 10−7 moles/l. and the percentages of the binding sites occupied by cortisol were 45, 24 and 40%, respectively. The mean values of the equilibrium constants were 2·9, 1·8 and 4·6 × 107 l./mole, suggesting that there might be a qualitative difference in transcortin from the three groups. The mean concentration of diffusible cortisol was 1·12 μg./100 ml. in men and 0·65 μg./100 ml. in non-pregnant and pregnant women. The significance of these findings is discussed.