SHBG and hypogonadism: The determination of total testosterone concentration in blood serum is used as a screening test for the diagnosis of hypogonadism; however, if a disorder related to sex hormone-binding globulin (SHBG) is suspected or the measured total testosterone concentration is low (200–400 ng/dL), it is recommended to determine the concentration of free testosterone, especially necessary in patients with CKD [18].