Testosterone, Free and Weakly Bound LabCorp

Free and weakly bound testosterone (FWBT) (also known as bioavailable testosterone) is thought to reflect an individual's biologically active and circulating testosterone in the body. Free and weakly bound testosterone includes free testosterone and testosterone that is bound to albumin. FWBT does not include sex hormond binding globulin-bound testosterone. The SHBG-bound fraction is biologically inactive because of the high binding affinity of SHBG for testosterone. The rapid dissociation o f"weakly bound" testosterone from albumin results in the availability of essentially all albumin-bound testosterone for steroid-receptor interaction. 

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