Hyperoxaluria is a long-term consequence of Roux-en-Y Gastric bypass: a 2-year prospective longitudinal study.

Abstract

BACKGROUND:

Recent studies suggest that patients undergoing Roux-en-Y gastric bypass (RYGB) for morbid obesity are at risk for hyperoxaluria, nephrolithiasis, and oxalate nephropathy. Our objective was to conduct a long-term prospective longitudinal study to establish the incidence, clinical progression, and severity of hyperoxaluria after RYGB.

STUDY DESIGN:

Patients undergoing RYGB between December 2005 and April 2007 provided 24-hour urine collections for comprehensive stone risk analysis 1 week before and 3 months and 1 and 2 years after surgery. Primary outcomes were changes in 24-hour urinary oxalate excretion and relative supersaturation of calcium oxalate from baseline to 2 years post-RYGB.

RESULTS:

The cohort consisted of 21 patients, including 5 (24%) men and 16 (76%) women. Mean preoperative age and body mass index (calculated as kg/m(2)) were 48.2 +/- 10.5 years (range 25 to 64 years) and 50.5 +/- 9.1 (range 39.7 to 66.6), respectively. Urinary oxalate excretion increased significantly after RYGB (33 +/- 9 mg/day versus 63 +/- 29 mg/day; p <or= 0.001). De novo hyperoxaluria developed in 11 (52%) patients. Increasing age at the time of surgery was predictive of de novo hyperoxaluria developing (odds ratio = 1.162; 95% CI, 1.002-1.347; p = 0.046). The percentage of patients with hypocitraturia increased from 10% at baseline to 48% at 2 years. The relative supersaturation of calcium oxalate was unchanged (1.73 +/- 0.67 versus 2.20 +/- 2.07; p = 0.27).

CONCLUSIONS:

RYGB is associated with a long-term increase in urinary oxalate excretion and decrease in urinary citrate excretion. Although calcium oxalate relative supersaturation increases early in the postoperative period, this returns to baseline with long-term follow-up. These data suggest that patients who have undergone RYGB are at risk for oxalate nephropathy developing.

• Authors: Branden G Duffey, Shaheen Alanee, Renato N Pedro, Bryan Hinck, Carly Kriedberg, Sayeed Ikramuddin, Todd Kellogg, Michelle Stessman, Angela Moeding, Manoj Monga
• Journal: Journal of the American College of Surgeons (J Am Coll Surg) Vol. 211 Issue 1 Pg. 8-15 (Jul 2010) ISSN: 1879-1190 [Electronic] United States
• PMID: 20610243 (Publication Type: Journal Article)
• Copyright: Copyright (c) 2010. Published by Elsevier Inc.

Topics

• Adult
• Age Factors
• Female
• Gastric Bypass (adverse effects)
• Humans
• Hyperoxaluria (etiology, urine)
• Longitudinal Studies
• Male
• Middle Aged
• Obesity, Morbid (surgery)
• Prospective Studies
• Risk Factors
• Statistics, Nonparametric