Proteinuria remission profiles in obesity-related kidney disease after bariatric surgery

Bariatric surgery improves obesity-related kidney dysfunction (ORKD), yet the determinants of full remission or persistent renal damage remain poorly understood. We evaluated factors associated with proteinuria remission after bariatric surgery in patients with ORKD. From a prospective cohort with 242 patients with obesity, a subgroup of 39 patients with obesity and proteinuria was followed for 21.3 mo after bariatric surgery. Pre- and postoperative assessments included anthropometric, metabolic, and renal parameters. Bariatric surgery led to a total weight loss of 38.5 ± 11.8%. Proteinuria and albuminuria declined significantly (Δproteinuria: -43.0%; Δalbuminuria: -14.3%). Higher preoperative percentage of albuminuria was associated with greater postoperative albuminuria reduction [hazard ratio (HR): 1.979; 95% confidence interval (CI): 0.686-3.272; P < 0.05]. Persistent proteinuria was observed in 25.6% of patients despite substantial weight loss and showed sex-related differences, as these patients were predominantly male (60.0% vs. 20.7%, P < 0.05). Persistent damage was also associated with lower serum creatinine (0.62 ± 0.07mg/dL vs. 0.72 ± 0.13mg/dL, P < 0.05), and higher estimated glomerular filtration rate (eGFR; 117.4 ± 8.8 vs. 104.8 ± 12.4mL/min/1.73 m², P < 0.05). In conclusion, patients with ORKD experienced marked reductions in proteinuria and albuminuria after bariatric surgery. However, a subset of patients-primarily males with higher baseline eGFR-had persistent proteinuria despite effective weight loss, suggesting the presence of potentially irreversible kidney damage.NEW & NOTEWORTHY In a carefully phenotyped, nondiabetic cohort with obesity-related kidney dysfunction, bariatric surgery markedly reduced proteinuria and albuminuria despite stable estimated glomerular filtration rate. Higher preoperative albuminuria was associated with greater postoperative improvement, whereas a substantial subset-predominantly males with higher baseline eGFR-showed persistent proteinuria despite effective weight loss. These exploratory findings suggest that renal recovery trajectories differ and support the existence of potentially irreversible kidney damage in selected patients.