"The only way to measure whether testosterone should be higher or lower is by trial and error. The best way to tell if your body needs more or less is by % Free Testosterone. If the "% Free" is low, and LH (Luteinizing Hormone) is high, then you need more testosterone. If LH is low, you don't need more.
Pretty simple. The only complication is FSH, because it indicates tumors, but for interpreting that you really do need a competent doctor."