Bariatric Surgery in Patients with a History of Nephrolithiasis: 24-h Urine Profiles and Radiographic Changes After Roux-en-Y Gastric Bypass Versus Sleeve Gastrectomy

Background: To evaluate the differences in 24-h urine profiles, radiographic imaging, and stone events post-Roux-en-Y gastric bypass versus sleeve gastrectomy in patients with a history of nephrolithiasis.

Methods: A retrospective review was conducted on 102 patients with a history of nephrolithiasis who then underwent bariatric surgery at our tertiary academic center. Computed tomography imaging and 24-h urine profile values were performed pre-operatively and at 1-year follow-up.

Results: A total of 60 patients underwent Roux-en-Y gastric bypass and 42 had sleeve gastrectomy. The Roux-en-Y gastric bypass group had significant increases in oxalate and decreases in citrate (p = 0.009 and 0.003, respectively), while the sleeve gastrectomy group had decreases in oxalate and stable citrate (p = 0.013 and 0.906, respectively). Roux-en-Y gastric bypass was the only significant predictor of post-operative hyperoxaluria (OR 7.1 [95% CI 2.3-21.3], p = 0.001). Radiographically, 38.3% of the Roux-en-Y gastric bypass group and 26.2% of the sleeve gastrectomy group had an increase in stone burden, and post-operative stone procedure rate was 10.0% and 7.1%, respectively.

Conclusions: At 1-year post-bariatric surgery, patients who underwent Roux-en-Y gastric bypass had exacerbated lithogenic urinary profiles, while those in sleeve gastrectomy patients improved. Although not statistically significant, stone burden increase and stone procedure rate were higher post-Roux-en-Y gastric bypass and will likely worsen at a longer follow-up due to the group's lithogenic 24-h urine profiles. These findings support pre-bariatric counseling and urinary monitoring in patients with a history of kidney stones who undergo RYGB, with a multi-disciplinary approach between urologists and general surgeons.