Effect of the Treatment with Allopurinol on the Endothelial Function in Patients with Hyperuricemia

Background. Hyperuricemia has been associated with an increased risk of endothelial dysfunction (ED), cardiovascular and renal disease. The role of uric acid (UA) on vascular damage is still controversial because previous studies have included patients with other risk factor for ED. Objective. To determine if the treatment with allopurinol improved endothelial function in hyperuricemic patients without other risk factors for ED. Material and methods. In order to gain more insight about the contribution of UA to the ED, we screened 369 apparently healthy male individuals for UA in a period of 9 months. Only 9 patients fulfill the inclusion criteria: UA plasma levels > 7 mg/dL without other risk factors for ED such as hypercholesterolemia, obesity, diabetes and hypertension. Results. Endothelial function, assessed by flow mediated dilatation (FMD) in the brachial artery improved significantly after 30 days of allopurinol treatment (9.6% [6.3-13.3%] vs. 13.7% [11-14.7%], p = 0.036), concomitantly with a decrease of about 45% in the uric acid plasma levels. Other parameters were not modified by allopurinol treatment. Any No significant correlation was found (r=-0.367, p = 0.33) between the Delta UA plasma levels (UA after treatment UA in basal conditions) and Delta FMD (FMD after treatment - FMD in basal conditions). Conclusions. These results strongly suggest that allopurinol improves flow-mediated vasodilation regardless of uric acid plasma concentrations.