title: Nephrolithiasis after bariatric surgery: A review of pathophysiologic mechanisms and procedural risk.
abstract: Obesity alone is a known risk factor for nephrolithiasis, and bariatric surgery has been linked to a higher incidence of post-operative new-onset nephrolithiasis. The mean interval from bariatric surgery to diagnosis of nephrolithiasis, ranges from 1.5 to 3.6 years. The stone risk is greatest for purely malabsorptive procedures, intermediate for Roux-en-Y gastric bypass and lowest for purely restrictive procedures (laparoscopic adjustable gastric banding, laparoscopic sleeve gastrectomy) where it approaches or is reduced below that of non-operative obese controls. A history of nephrolithiasis and increasing age at the time of surgery are both associated with an increased risk of new stone formation post-operatively. The underlying pathophysiologic changes following bariatric surgery include increased colonic absorption of oxalate leading to hyperoxaluria, hypocitraturia and increased urinary calcium oxalate supersaturation, which predispose to stone formation. The majority of incident stones are medically managed, with some requiring interventions in the form of lithotripsy or ureteroscopy.
authors.affiliation: Aga Khan University Hospital, Department of Surgery, Stadium Road, P. O. Box 3500, Karachi, 74800, Pakistan.
authors.forename: Umer Hasan
authors.initials: UH
authors.lastname: Bhatti
authors.affiliation: Yale University School of Medicine, Department of Surgery, 40 Temple Street, Suite 7B, New Haven, CT, 06510, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Duffy
authors.affiliation: Yale University School of Medicine, Department of Surgery, 40 Temple Street, Suite 7B, New Haven, CT, 06510, USA.
authors.forename: Kurt Eric
authors.initials: KE
authors.lastname: Roberts
authors.affiliation: Aga Khan University Hospital, Department of Surgery, Stadium Road, P. O. Box 3500, Karachi, 74800, Pakistan. Electronic address: amir.shariff@aku.edu.
authors.forename: Amir Hafeez
authors.initials: AH
authors.lastname: Shariff
mesh_terms: D050110:Bariatric Surgery / Q000009:adverse effects* / Q000379:methods; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D006959:Hyperoxaluria / Q000150:complications; D015994:Incidence; D053040:Nephrolithiasis / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D011184:Postoperative Period; D012307:Risk Factors; D013997:Time Factors
keywords: Bariatric surgery; Complications; Enteric hyperoxaluria; Malabsorptive procedures; Nephrolithiasis; Restrictive procedures