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Corticosteroid-Binding Globulin

Meaning

Corticosteroid-Binding Globulin (CBG), also scientifically known as transcortin, is a vital plasma glycoprotein predominantly synthesized in the liver that acts as the principal carrier protein for glucocorticoids and progestins in the systemic circulation. Its primary physiological role is to bind and transport cortisol, the body’s main stress hormone, and to a lesser extent, progesterone. CBG is a crucial modulator of hormone bioavailability because only the small, unbound fraction of these steroids is biologically active and capable of initiating cellular signaling. Fluctuations in CBG concentration, influenced by various endocrine states, profoundly affect the effective free concentration of circulating cortisol.