Resolution of Microalbuminuria and Dysmetabolism Following Bariatric Surgery: Prospective Study

Overview

Favorable effects of bariatric surgery have been demonstrated in particular regarding increased insulin sensitivity, decreased blood pressure, improved blood lipids and decreased cardiovascular risk. After surgery, weight loss also leads to improvement of the chronic inflammatory state related to obesity, a strong predictor of the metabolic status. Although obese patients are often affected with type 2 diabetes and hypertension, both related to renal impairment, the existence of a distinct mechanism by which obesity would cause chronic renal insufficiency has been suggested. The mechanisms underlying obesity-related nephropathy have been proposed to involve hyperfiltration, expansion of mesangial cells, hyperperfusion leading to proteinuria and glomerulosclerosis, as noted in obese dogs. In humans, improvements in renal function may be observed following bariatric surgery, although some reported a possibility of increased nephrolithiases. Whether biliopancreatic diversion and gastrectomy alone have similar effects is uncertain. More prospective studies are needed to assess the impact of all types of weight loss surgery to reverse chronic renal insufficiency. The objective of this study is to document changes in microalbuminuria and metabolic parameters in patients with altered renal function undergoing bariatric surgery. Patients enrolled in the study will show renal function impairment as demonstrated by albumin/creatinine ratio alterations in 2 out of 3 measurements taking place before surgery. We will perform a prospective study of renal function markers (albumin/creatinine ratio) and metabolic parameters (blood lipids, glucose, insulin, inflammatory markers) before and 6, 12, 24 months after surgery in patients with microalbuminuria at study onset (albumin/creatinine ratio 2.0-20.0 mg/mmol in men and 2.8-28.0 mg/mmol in women). Data will be analysed with repeated measures analyses in both subgroup. Thereafter, a linear regression model will be created to adjust for potentially confounding factors such as hypertension and diabetes. We hypothesize that patients with severe obesity and altered renal function, whether they are diabetic or not, have improved microalbuminuria and metabolic parameters following biliopancreatic diversion with sleeve gastrectomy or sleeve gastrectomy alone. The extent of renal function recovery will correlate directly with metabolic improvements.