There were no between-group differences in age, smoking habits, reasons for hyperprolactinemia, the body mass index, blood pressure, glucose, HOMA1-IR, thyrotropin, free thyroid hormones, total prolactin, monomeric prolactin, macroprolactin, FSH, LH, ACTH and IGF-1 (Table 1 and Table 2). This evidence concerns the gene PLOD1 and hyperprolactinemia.