Binding of Corticosteroids by Plasma Proteins

The role of the blood plasma in the transport of nutrients, metabolic intermediates, and hormonal agents has long been recognized, yet there is now an increasing awareness of the degree to which plasma proteins may be specialized for this function. Uniquely adapted proteins are responsible for the transport of nearly all the neutral fat, cholesterol, and phospholipids of the plasma in colloidal solution.¹The free fatty acids of plasma, which have recently been shown to be of great importance in fat transport from the peripheral depots to the sites of oxidation, circulate nearly completely bound to the plasma albumin.²Albumin also binds many other substances of physiologic significance. Most of the circulating iron of the plasma is bound to an iron-binding globulin.³The degree of binding of thyroxine to a thyroxine-binding protein is well known and is made the basis of the familiar clinical index of thyroid