SHBG and male infertility: With regard to male infertility, these include the aromatization of testosterone to estrogen in peripheral tissues, decreased sex hormone-binding globulin (SHBG) production in the liver [15,16], increased endorphin concentrations [leading to lower luteinizing hormone (LH) pulse and gonadotropin releasing hormone (GnRH) production] [17] and increased oxidative stress, which promotes sperm DNA damage [18].