Only 3% of circulating testosterone (T) if not bound to a carrier protein call sex hormone binding globulin (SHBG), and the unbound “free” portion is the active portion. With aging our SHBG tends to increase resulting in less free T. A common pattern in lab testing is to have a pretty good total T level with a low free T level, thus effectively resulting in low T.

By lowering SHBG one can increase the free T level. If total T production is good then this is preferable to supplementing T with a prescription.

Supplements to lower SHBG