Alfacalcidol [17], cholecalciferol, and ergocalciferol showed a positive impact on anemia in hemodialysis (HD) patients [18], while calcitriol improved hemoglobin Hb levels and reduced the need for EPO in CKD patients on conservative management and on dialysis [12, 19]; finally, a recent study evaluating 1-year treatment with paricalcitol in 12 HD patients previously treated with calcitriol, showed an amelioration of erythropoiesis during paricalcitol treatment [20]. Here, GSTM1 is linked to anemia (phenotype).