Bound vs. Free Testosterone
Only a very small amount of free testosterone is available to interact with cell receptors. Most will bind to the albumin and SHBG proteins in the protein, momentarily inhibiting the hormone's action. Other names for SHBG include testosterone-estradiol-binding globulin and sex steroid-binding globulin. Steroid hormones bind to SHBG far more strongly than albumin, with an affinity that is approximately 1,000 times greater, even though albumin is present at a level that is 1,000 times higher than SHBG. Because of this,...