A nonlabeled method to evaluate cortisol production rate by modeling plasma CBG-free cortisol disposition.

Nicole Picard-Hagen (1) , Véronique V. Gayrard-Troy (1) , Michel Alvinerie (2) , Hélène Smeyers (1) , Raphael Ricou (1) , Alain Bousquet‐mélou (1) , Pierre-Louis Toutain (1)

1 UPTE - Physiopathologie et Toxicologie Expérimentales
2 UPT - Unité de recherche Pharmacologie-Toxicologie

This study aimed to develop a nonlabeled method for the measurement of cortisol production rate to evaluate adrenal function. The cortisol production rate determination requires that of cortisol clearance, which is not a parameter but a variable resulting from the saturable binding of cortisol to corticosteroid-binding globulin (CBG). Our method is based on evaluation of the plasma clearance of the CBG-free cortisol fraction. This parameter was evaluated from a pharmacokinetic model of total plasma cortisol disposition that takes into account specific binding of the corticoid to CBG in the plasma. We have shown that the CBG-free cortisol kinetics and CBG-binding parameters thus evaluated are not statistically different from those obtained by the radioisotopic method and equilibrium dialysis, suggesting that the plasma CBG-free cortisol clearance is independent of the total plasma cortisol concentrations and represents the actual parameter of cortisol elimination. We validated this modeling approach by using it to calculate the in vivo entry rate of cortisol mimicked by the perfusion of cortisol at a known rate.

Mots clés: Animals; Blood Proteins; Kinetics; Mathematics; Protein Binding; Sheep; Transcortin; Tritium

Mots clés: Female; Hydrocortisone; Models; Biological

Domaines: Pharmacologie

Nicole Picard-Hagen, Véronique V. Gayrard-Troy, Michel Alvinerie, Hélène Smeyers, Raphael Ricou, et al.. A nonlabeled method to evaluate cortisol production rate by modeling plasma CBG-free cortisol disposition.. AJP - Endocrinology and Metabolism, 2001, 281 (5), pp.E946-56. ⟨10.1152/ajpendo.2001.281.5.E946⟩. ⟨hal-00517589⟩