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

Abstract Objective: To compare oxidative stress (OS) between patients with renal stone disease and healthy volunteers by measuring 8-hydroxy- 2’-deoxyguanosine (8-OHdG) levels in urine. Methods: In this prospective case-control study, we measured 24-hour urinary 8-OHdG levels in patients with urolithiasis and compared them with matched healthy controls. We also measured 24-hour urinary uric acid, calcium, oxalate and citrate levels in patients with renal stone disease and studied their relation with urinary 8-OHdG levels. Results: In this study, 75 cases of renal stone disease and 75 well-matched controls were included. Median 24-hour urinary 8-OHdG levels were significantly higher in cases compared to controls (7.6vs. 3.7µg/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, sensitivity and specificity of 84% each were obtained. A positive correlation between 8-OHdG (µg/g of creatinine) and 24-hour 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-hour urinary oxalate levels to be an independent predictor of urinary 8-OHdG levels. Conclusion: Oxidative stress is significantly higher in patients with renal stone diseases compared to healthy controls. Urinary oxalate levels were significantly correlated with urinary 8-OHdG levels.