The effect of bariatric surgery on renal function.

Area of Science:

• Nephrology
• Bariatric Surgery
• Metabolic Disorders

Background:

• Obesity is a significant risk factor for chronic kidney disease (CKD), often presenting with albuminuria and impaired renal function.
• Previous research indicated that Roux-en-Y gastric bypass (RYGB) can improve albuminuria in non-diabetic individuals.

Purpose of the Study:

• To evaluate the impact of RYGB and sleeve gastrectomy on renal function, specifically urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR).
• To assess changes in renal parameters one year after bariatric surgery in a larger cohort of patients with normal or mildly impaired renal function.

Main Methods:

• Retrospective analysis of patients undergoing RYGB or sleeve gastrectomy.
• Inclusion criteria: availability of preoperative and 1-year postoperative serum/urine albumin and creatinine, and weight.
• Exclusion criteria: preoperative chronic kidney disease (CKD) Stage 3 or higher, or macroalbuminuria (UACR ≥ 300 mg/g).

Main Results:

• 158 patients (84.2% White Hispanic, 91.8% female) were analyzed.
• Urinary albumin-to-creatinine ratio (UACR) significantly decreased from 21.5±3.2 mg/g preoperatively to 10.2±1.2 mg/g at 1 year (P<.0001).
• Microalbuminuria resolved in 82% of affected patients; mean eGFR decreased from 97.5±2.2 to 87.1±2.0 mL/min (P<.0001), with hyperfiltration resolving in nearly half.

Conclusions:

• Bariatric surgery led to a significant reduction in albuminuria, with microalbuminuria resolving in the majority of patients.
• A modest decrease in eGFR was observed, shifting from normal to Stage 2 CKD range at 1 year post-surgery.
• The study highlights the renal benefits of bariatric surgery in an obese, predominantly female minority population, but suggests the need for prospective research.