Evaluation of change in oxidative stress in urolithiasis patients following complete stone clearance: A prospective observational study.

Introduction: Prior studies showed that oxidative stress (OS) is increased in patients with urolithiasis. Urinary 8-hydroxy 2-deoxyguanosine (8-OHdG) is a well-established marker of OS, and its levels are elevated in patients with urolithiasis. It is unknown whether this increased OS persists even after stone removal. We aimed to evaluate the change in urinary 8-OHdG levels in patients with urolithiasis following complete stone clearance.

Methods: A prospective pre-post study was conducted at a single center (Institute Ethics Committee approval: NK/5965/MS/029). Patients with urolithiasis undergoing surgery for stone clearance were included. Patients with known comorbidities, malignancy, systemic illnesses, body mass index >30 kg/m², age >50 years, serum creatinine >1.5 mg/dl, and incomplete clearance were excluded. Twenty-four-hour urinary 8-OHdG levels were measured using the Enzyme-Linked Immunosorbent Assay method preoperatively and 3 months post-surgery.

Results: Forty patients (24 males) with a mean age of 34.65 (±11.02) years were analyzed. Thirty-seven patients had renal stones, while 3 had proximal ureteral stones (median stone size = 20 mm). Percutaneous nephrolithotripsy was performed in 33 patients, while 7 underwent various other surgical procedures for stone removal. There was no significant difference in urinary 8-OHdG levels following stone clearance; preoperative 25.770 (1.47-60.38)-μg/g-creatinine versus postoperative value of 32.00 (6.57-117.35)-μg/g-creatinine; P = 0.63. No significant correlation was found between age, gender, smoking or alcohol consumption, degree of hydronephrosis or stone burden, and urinary 8-OHdG levels.

Conclusions: The baseline OS in urolithiasis patients does not change after complete stone clearance. Whether this persistent OS is responsible for stone recurrence needs to be explored.