Iron Indices and Vitamin D Receptor Polymorphisms in Hemodialysis Patients

Cardiovascular disease caused by accelerated atherosclerosis is the major determinant of morbidity and mortality in chronic kidney disease patients. Vitamin D and its analogs provide survival benefit for hemodialysis (HD) patients. Vitamin D exerts its effects through the vitamin D receptor (VDR) that is coded for by a gene showing several polymorphisms that, in turn, are associated with a variety of diseases and differential responses to vitamin D. In this study, we evaluated the association between 4 VDR polymorphisms (ie, those identified by the restriction enzymes BsmI, ApaI, TaqI, and FokI) and iron indices (serum iron, transferrin, transferrin saturation, and ferritin) in 88 hemodialysis patients routinely treated with vitamin D. The absence or presence of the BsmI, ApaI, TaqI, and FokI restriction sites were denominated B and b, A and a, T and t, F and f, respectively. Our results show that in HD patients with transferrin saturation <20%, the F allele was more frequent than in HD patients with transferrin saturation >20% (P = .03). This relationship may provide a link between VDR alleles and iron and nutritional markers, which are highly predictive variables of cardiovascular morbidity and mortality in hemodialysis patients.

Index Words: Vitamin D receptor, Gene polymorphism, Chronic kidney disease, Hemodialysis, Iron indices, Transferrin saturation