EPO and vitamin D deficiency: In addition, vitamin D shows anti-inflammatory properties that improve responsiveness to EPO through the reduced production of hepcidin and pro-inflammatory cytokines [7, 13], whose concentrations increase during vitamin D deficiency in bone marrow and impair erythropoiesis [14]; VDRs activation, conversely, up-regulates the lymphocytic release of anti-inflammatory interleukin-10 (IL-10) which exerts proliferative effects on erythroid progenitors [12, 15].