Do you suspect that you have low levels of testosterone for your age? With our venous blood test, you can measure the total testosterone, albumin, and SHBG in your blood to estimate the amount of testosterone available in your body. Total testosterone is the amount of testosterone present in your body. However, not all this testosterone is available for the body to use because some of it is bound to a protein called sex hormone binding globulin (SHBG) and cannot be released to the cells. A proportion of testosterone is also loosely bound to another protein called albumin. The rest of the testosterone in the body (about 1-2%) is unbound or free for the cells to use.