Improved renal function 12 months after bariatric surgery.

BACKGROUND: Obesity is a risk factor for developing chronic kidney disease (CKD) that may be improved with bariatric surgical weight reduction. The objective of this study was to investigate changes in the glomerular filtration rate (GFR) in severely obese patients 1 year after bariatric surgery.

METHODS: GFR was measured in 233 severely obese patients before and more than 12 months after bariatric surgery. Patients were separated by baseline GFR: hyperfiltration (GFR>125 mL/min), normal (GFR 125-90 mL/min), CKD stage 2 (GFR 89-60 mL/min), and CKD stage 3 (59-30 mL/min). The groups were reanalyzed 12 months after bariatric surgery.

RESULTS: Of the 233 patients, 61 (26.2%) had hyperfiltration, 127 (54.5%) were normal, 39 (16.7%) had CKD stage 2, and 6 (2.6%) had CKD stage 3. The mean GFR was 146.4±17.1 mL/min in the hyperfiltration group, 105.7±9.6 mL/min in the normal group, 76.8±16.7 mL/min in the CKD stage 2 group, and 49.5±6.6 mL/min in the CKD stage 3 group. The mean GFR 1 year after weight loss surgery decreased to 133.9±25.7 mL/min in the hyperfiltration group, increased to 114.2±22.2 mL/min in the normal group, increased to 93.3±20.4 mL/min in the CKD stage 2 group, and increased to 66.8±19.3 mL/min in the CKD stage 3 group.

CONCLUSIONS: Abnormal renal function was common in severely obese patients. Bariatric surgery-induced weight loss had positive effects on renal function at 1 year after surgery.