Corticosteroid-Binding Globulin (CBG) Blood Test

The CBG Blood Test measures Corticosteroid-binding globulin (CBG, transcortin), the main transport protein for cortisol and corticosterone in vertebrates. This protein binds glucocorticoids with high affinity. In some species, it also binds progesterone and to a lesser extent testosterone. Its specificity varies among species. CBG is important in regulating the actions of glucocorticoids.

Description

Corticosteroid-binding globulin (CBG) is the specific high-affinity plasma transport glycoprotein for cortisol. Stress-induced falls in CBG levels may heighten hypothalamic–pituitary–adrenal axis responses and CBG:tissue interactions may allow targeted cortisol delivery. Three genetic variants of CBG have been identified that reduce cortisol binding affinity and/or CBG levels.