The primary form of coisol in the plasma is that which is: (A) Bound to albumin, (B) Bound to transthyretin, (C) Free in solution, (D) Bound to coicosteroid-binding globulin (CBG)
Answer is D. The majority of coisol is bound to a specific carrier protein, coicosteroid binding globulin (CBG), while smaller amounts are bound nonspecifically to albumin. Few, if any, coisol receptors would be expected in the plasma and transthyretin binds primarily thyroxine.