Abstract Introduction The association between obesity and renal dysfunction has been widely studied. Albuminuria is a cardiovascular risk factor and the most prevalent marker of kidney injury in people with obesity. Despite the higher prevalence of hypertension and diabetes in those patients, other contributing factors are still unknown. We aimed to explore the factors related to albuminuria in obesity, analyzing its variation after bariatric surgery. Methods We evaluated 2518 patients undergoing bariatric surgery, of those, 1243 with preoperative albuminuria measurement were included in this study. Albuminuria was determined by the albumin-creatinine ratio (RAC) in an occasional urine sample (mg/g) or by the 24-hour urine albumin excretion rate (TEA) (mg/24h). Means and medians were compared using Student’s T-test or Mann-Whitney tests, respectively. Spearman correlation was used. Results Age (ρ = 0.073; p = 0.010), body mass index (BMI) (ρ = 0.139; p <0.001), waist circumference (WC) (ρ = 0.220; p <0.001), glycated hemoglobin (HbA1C) (ρ = 0.221; p <0.001), systolic blood pressure (SBP) (ρ = 0.203; p <0.001), diastolic blood pressure (DBP) (ρ = 0.134; p <0.001), uricemia (ρ = 0.141; p <0.001) and C-reactive protein (CRP) levels (ρ = 0.090; p = 0.017) were positively correlated with albuminuria.Patients with albuminuria (TEA / RAC≥30) had higher BMI (45.0 ± 6.0 vs.43.2 ± 5.6kg / m2; p <0.001), WC (129.3 ± 13.1 vs. 122.0 ± 12.9cm; p <0.001), SBP (142.7 ± 18.0 vs.134.1 ± 16.5mmHg; p <0.001), DBP (88.0 ± 12.6 vs.83, 2 ± 10.3mmHg; p <0.001), uricemia (6.1 ± 1.5 vs.5.4 ± 1.4mg / dL; p <0.001) and CRP (11.3 (16.4) vs.8, 3 (9.6) mg / L; p <0.001).Excluding patients with diabetes and hypertension, BMI and WC remained statistically positively correlated with urinary albumin excretion. After surgery, the decrease of albuminuria was correlated with the reduction of HbA1C (ρ = 0.144; p <0.001) and CRP (ρ = 0.113; p = 0.037). Conclusion Anthropometric, inflammatory and metabolic factors, namely WC, CRP and uricemia, may be involved in the etiopathogenesis of albuminuria in obese patients. Bariatric surgery is the most effective method to reverse obesity and it has been shown to be a promising therapy on the treatment of associated renal dysfunction.