Uric acid nephrolithiasis

Abstract

Uric acid nephrolithiasis accounts for 5-10 % of all kidney stones in the general population in the United States (US) and is noted to be increasing in other parts of the world like Japan, previously known to have a low incidence of this condition. This increase is attributable, at least in part, to westernized eating habits. The prevalence of uric acid nephrolithiasis has continued to rise at alarming rates in high risk populations, such as patients with type 2 diabetes mellitus, obesity and metabolic syndrome. In these conditions, there are changes in the serum and urine chemistries leading to more acidic urine and chronically increased uric acid production, which are both pre-requisites for the formation of uric acid stones. The clinical presentation is similar to any other kidney stone that includes pain radiating from the flank into the pelvic area, as the stone moves downward, and concomitant associated symptoms such as nausea, vomiting, fever and hematuria can be also present. These stones are diagnosed by CT as plain x-rays are not helpful since uric acid stones are not radiopaque. The treatment for uric acid stones is well-defined nowadays; consisting of alkalinizing the urine and increasing fluid intake, and in selected cases, the use of xanthine oxidase inhibitors might be needed. In this review, we focus on the pathophysiology diagnoses, causes, treatment and prevention of uric acid stones.