Free, bio-available and total testosterone
Only 1 - 2% of circulating testosterone is not bound to protein. This fraction is termed free testosterone.11 Approximately 40 - 50% of circulating testosterone is weakly bound to albumin.11
The free and albumin-bound testosterone is referred to as bio-available. The remaining testosterone in circulation is strongly bound to SHBG. The amount of SHBG in circulation therefore influences the amount of bio-available testosterone. SHBG can be altered by factors such as age, hepatic cirrhosis and hepatitis, hyperthyroidism, obesity and the use of anticonvulsants.9
Total testosterone refers to circulating, bio-available and SHBG-bound testosterone.
Total testosterone refers to circulating, bio-available and SHBG-bound testosterone.
