Testosterone Levels	

Normal testes contain approximately 25µg of testosterone so that the testicular hormone turns over more than two hundred times to provide the average of 5–10mg secreted daily. In normal men, approximately two per cent of plasma testosterone is free (unbound), forty-four per cent is bound to testosterone-binding globulin (TeBG, also known as sex steroid hormone-binding globulin or SHBG), and fifty-four per cent is bound to albumin and other proteins. Since albumin-bound testosterone is available for tissue uptake, bioavailable testosterone (the free component plus the albumin-bound component) is equal to some fifty per cent of the total amount. 

See also:
• Phases of Normal Testicular Function