Crossover Clinical Trial, Randomized, Double Blind, Placebo Controlled Trial

The purpose of this study is to determine the effect of inhibiting xanthine oxidase with allopurinol in patients with chronic kidney disease in asymptomatic hyperuricemia endothelial injury and vascular repair mechanisms, evaluating the plasma concentration of angiogenic factors, microparticles of endothelial cells and the cell number circulating endothelial progenitor.