Effect of bariatric surgery on normal and abnormal renal function

Bariatric surgery does not have a negative effect on renal function as measured by the CR, whether CR at baseline is <1.3 or ≥1.3 mg/dL when monitored for ≥24 months. For those with impaired renal function and a CR ≥1.3 mg/dL, improvement in CR was seen in 76.7% at ≥2 years postoperatively, at a point at which the weight loss velocity, hydration, and nutritional status have stabilized. The weight loss associated with bariatric surgery could potentially have a positive effect on renal function at ≥24 months, such as was found in the present study by a stable or reduced CR level. The etiology for this might be a direct effect of weight loss on impaired renal function or an indirect effect by reducing the rates of co-morbidities, such as diabetes mellitus and hypertension, both risk factors for renal disease. Additional prospective studies, including weight-matched controls, are needed.