A prospective case-control study on the evaluation of oxidative stress in renal stone formers

Association of increased oxidative stress (OS) with the pathophysiology of renal stone formation has not been explored greatly in the field of urolithiasis. In this prospective case-control study, we measured 24-h urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in patients with urolithiasis and compared them with matched healthy controls. We also measured 24-h urinary uric acid, calcium, oxalate, and citrate levels in patients with renal stone disease and studied their relation with urinary 8-OHdG levels. Seventy-five cases of renal stone disease and 75 well-matched controls were included. Median 24-h urinary 8-OHdG levels were significantly higher in cases compared to controls (7.6 vs. 3.7 µg/g of creatinine; p < 0.000). Receiver-operating curve (ROC) analysis for 8-OHdG between cases and controls revealed an area under the curve of 0.90. At 8-OHdG (µg/g of creatinine) value of 5 or more, a sensitivity and a specificity of 84% each were obtained. A positive correlation between 8-OHdG (µg/g of creatinine) and 24-h urinary oxalate level was noted (r = 0.461, p = 0.000). No correlation between 8-OHdG (µg/g of creatinine) and other variables was noted. On multivariate linear regression analysis, we noted 24-h urinary oxalate levels to be an independent predictor of urinary 8-OHdG levels. OS is significantly higher in patients with renal stone diseases compared to healthy controls. Urinary oxalate levels were significantly correlated with urinary 8-OHdG levels.