Sex Hormone Binding Globulin (SHBG) test measures the level of SHBG in your blood. SHBG is a glycoprotein made by the liver that binds to the three sex hormones, estrogen, testosterone and dihydrotestosterone that is found in both women and men. SHBG carries these sex hormones throughout the blood. The hormone that is critical in this test is testosterone, although SHBG binds all the three hormones. SHBG controls the level of testosterone that can be used by the body tissue. Too much testosterone in women and too little testosterone in men can cause problems. The level of SHBG in the blood changes due to factors like age and sex. The level can also change due to several disorders like hyperthyroidism, liver disease, and obesity.