Obesity-Related Kidney Disease in Bariatric Surgery Candidates

Background Obesity has a negative impact in kidney health. However, the hallmarks of kidney dysfunction in bariatric surgery candidates are poorly characterized. To address this knowledge gap, we used a propensity score-matched analysis to compare kidney lesion biomarkers in bariatric surgery candidates and living kidney donors. Methods Bariatric surgery candidates attending a single center for obesity treatment were pair-matched for sex and age to potential living kidney transplant donors (PLKD) using a 1:1 nearest-neighbor approach (N = 400, n = 200/group). A 24-h urine collection was used to analyze proteinuria and creatinine clearance. Results Patients with obesity (PWO) had higher creatinine clearance when compared to PLKD (143.35 +/- 45.50 mL/min vs 133.99 +/- 39.06 mL/min, p = 0.03), which was underestimated when correction for body surface area (BSA) was used (creatinine clearance corrected for BSA of 115.25 +/- 33.63 mL/min/1.73 m(2) in PWO vs 135.47 +/- 35.56 mL/min/1.73 m(2) in PLKD). Proteinuria was also higher in PWO compared to PLKD (139.82 +/- 353.258 mg/day vs 136.35 +/- 62.24 mg/day, p < 0.0001). Regression analysis showed that creatinine clearance was strongly correlated with proteinuria in PWO (HR 1.522, p = 0.005), but it was less evident in PLKD (HR 0.376, p = 0.001). Conclusion Hyperfiltration and disproportionate proteinuria are frequent in patients with obesity. Since hyperfiltration can be underestimated by adjusting creatinine clearance for BSA, this should not be used when evaluating kidney function in bariatric surgery candidates.