Physiology The primary form of cortisol in the plasma is that which is: A Bound to albumin B Bound to transthyretin C Free in solution D Bound to corticosteroid-binding globulin (CBG) 💡 Explanation The primary form of cortisol in the plasma is that which is: ✓ Correct Answer: D. Bound to corticosteroid-binding globulin (CBG)