Exploring Renal Changes after Bariatric Surgery in Patients with Severe Obesity

Obesity-related hyperfiltration leads to an increased glomerular filtration rate (GFR) and hyperalbuminuria. These changes are reversible after bariatric surgery (BS). We aimed to explore obesity-related renal changes post-BS and to seek potential mechanisms. Sixty-two individuals with severe obesity were prospectively examined before and 3, 6 and 12 months post-BS. Anthropometric and laboratory data, 24 h-blood pressure, renin-angiotensin-aldosterone system (RAS) components, adipokines and inflammatory markers were determined. Both estimated GFR (eGFR) and albuminuria decreased from the baseline at all follow-up times (p-for-trend <0.001 for both). There was a median (IQR) of 30.5% (26.2-34.4) reduction in body weight. Plasma glucose, glycosylated hemoglobin, fasting insulin and HOMA-index decreased at 3, 6 and 12 months of follow-up (p-for-trend <0.001 for all). The plasma aldosterone concentration (median (IQR)) also decreased at 12 months (from 87.8 ng/dL (56.8; 154) to 65.4 (56.8; 84.6), p = 0.003). Both leptin and hs-CRP decreased (p < 0.001) and adiponectine levels increased at 12 months post-BS (p = 0.017). Linear mixed-models showed that body weight (coef. 0.62, 95% CI: 0.32 to 0.93, p < 0.001) and plasma aldosterone (coef. -0.07, 95% CI: -0.13 to -0.02, p = 0.005) were the independent variables for changes in eGFR. Conversely, glycosylated hemoglobin was the only independent variable for changes in albuminuria (coef. 0.24, 95% CI: 0.06 to 0.42, p = 0.009). In conclusion, body weight and aldosterone are the main factors that mediate eGFR changes in obesity and BS, while albuminuria is associated with glucose homeostasis.

Automated summary

Obesity-related hyperfiltration causes an increase in GFR and hyperalbuminuria, which can be reversed after bariatric surgery. Body weight and aldosterone are the main factors mediating changes in eGFR in obesity and bariatric surgery, while albuminuria is associated with glucose homeostasis.