Urolithiasis and sleeve gastrectomy: a prospective assessment of urinary biochemical variables

INTRODUCTION: to evaluate urinary biochemical alterations related to urolithogenesis processes after sleeve gastrectomy (SG). MATERIALS AND METHODS: : prospective study with 32 individuals without previous diagnosis of urolithiasis who underwent SG. A 24-h urine test was collected seven days prior to surgery and at 6-month follow-up. The studied variables were urine volume, urinary pH, oxalate, calcium, citrate, and magnesium and calcium oxalate super saturation (CaOx SS). RESULTS: patients were mainly women (81.2%), with mean age of 40.6 years. Mean pre- and postoperative BMI were 47.1 ± 8.3 Kg/m(2) and 35.5 ± 6.1 Kg/m(2), respectively (p<0.001). Urine volume was significantly lower at the postoperative evaluation in absolute values (2,242.50 ± 798.26 mL x 1,240.94 ± 352.39 mL, p<0.001) and adjusted to body weight (18.58 ± 6.92 mL/kg x 13.92 ± 4.65 mL/kg, p<0.001). CaOx SS increased significantly after SG (0.11 ± 0.10 x 0.24 ± 0.18, p<0.001). Moreover, uric acid levels were significantly lower at the postoperative evaluation (482.34 ± 195.80 mg x 434.75 ± 158.38 mg, p=0.027). Urinary pH, oxalate, calcium, citrate, and magnesium did not present significant variations between the pre- and postoperative periods. CONCLUSION: SG may lead to important alterations in the urinary profile. However, it occurs in a much milder way than that of RYGB.