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Sex hormone-binding globulin 101 or SHBG is a controversial topic. Al lot of people just load up on Proviron to competitively inhibit SHBG without knowing what it does.

So lets go over the basics:

SHBG binds sex hormones.  DHT more than testosterone more than estrodiol.  So the more SHBG the les free testosterone floating around.  Free testosterone tends to be broken down quickly, when free levels go down the concentration of free:bound decrease so basic chemistry results in the currently bound unbinding to regenerate the free pool. so its not necessarily bad.  

SHBG is made in the liver and is down regulated by adrogens like testosterone and DHT as well as growth hormone, IGF1 and Insulin. Basicaly everything a bodybuilder would take to build muscle will cause SHBG to go down.  Estrogens, thyroxin and rare drugs cause SHBG to go up.  So not only do women make more estrogen and less testosterone but the estrogen causes SHBG to go up which binds the free test more in women so the ratio of free test:estradiol is even lower.

What people may not know about SHBG is that on certain organs which typicaly have receptors for sex hormones, there is a spefific SHBG receptor! In order for SHBG to bind to its receptor it can’t be bound to any hormone. But after it binds to its receptor If it binds to a hormone like estrodiol or DHT it alters the way that cell responds to the normal hormone receptor complex.  The results are counterintuitive and not wel understood.  For instance its obvious the prostate would be activated by DHT activity right? But the SHBG-receptor/DHT complex DEACTIVATES healthy Prostate cells but ACTIVATES prostate cancer cells.  It actualy gets alot more complicated than that. Inactive metabolites of the hormones may have active binding and functioning when bound to the SHBG/SHBGrecptor complex.

So the SHBG molecule is a functional hormone not just  a carrier molecule and should probably left alone since we don’t completely know what it does.‎