T Nation

Testing Free T vs Bioavailable T

Guys, for my upcoming blood work I was only able to get Total Test and Bio Available Test, but not Free Test. Is Bio Available on par or better/more accurate then Free Test? Do the same ratios apply? Do the numbers of free and bio T usually mirror each other? Thanks…

Are you able to get SHBG? Albumin?

Most testosterone is bound by SHBG, a carrier protein and roughly half of it, depending on your reference. The remainder is considered bioavailable and of that, approximately 2% is free. Free testosterone is what works in the cells. Bioavailable testosterone that is not free is bound by albumin, like SHBG, a carrier protein. However, albumin has a low binding affinity and albumin bound test can easily be break free do the good stuff.

If you measure albumin, with SHBG and total testosterone, free testosterone can be calculated.