Considering the reference limits for serum prolactin established by the laboratory where the determinations were made (non-pregnant women: 2–23 ng/mL, postmenopausal women: 3–15 ng/mL and men: 2–15 ng/mL), we identified hyperprolactinemia in 7.25% (3 women and 2 men) of patients in pre-dialysis stages and 43.2% (18 women and 18 men) among HD patients. The gene discussed is PRL; the disease is hyperprolactinemia.