Steatorrhea and hyperoxaluria occur after gastric bypass surgery in obese rats regardless of dietary fat or oxalate.

Abstract

PURPOSE:

We determined the effect of dietary fat and oxalate on fecal fat excretion and urine parameters in a rat model of Roux-en-Y gastric bypass surgery.

MATERIALS AND METHODS:

Diet induced obese Sprague-Dawley® rats underwent sham surgery as controls (16), or Roux-en-Y gastric bypass surgery (19). After recovery, rats had free access to a normal calcium, high fat (40%) diet with or without 1.5% potassium oxalate for 5 weeks and then a normal (10%) fat diet for 2 weeks. Stool and urine were collected after each period. Fecal fat was determined by gas chromatography and urine metabolites were evaluated by assay spectrophotometry.

RESULTS:

Daily fecal fat excretion remained low in controls on either diet. However, Roux-en-Y gastric bypass rats ingested a food quantity similar to that of controls but had eightfold higher fecal fat excretion (p <0.001) and heavier stools (p = 0.02). Compared to controls, gastric bypass rats on the high fat diet with potassium oxalate had a fivefold increase in urine oxalate excretion (p <0.001), while gastric bypass rats without potassium oxalate had a twofold increase in urine calcium (p <0.01). Lowering dietary fat in gastric bypass rats with potassium oxalate led to a 50% decrease in oxalate excretion (p <0.01), a 30% decrease in urine calcium and a 0.3 U increase in urine pH (p <0.001).

CONCLUSIONS:

In this Roux-en-Y gastric bypass model high fat feeding resulted in steatorrhea, hyperoxaluria and low urine pH, which were partially reversible by lowering the dietary fat and oxalate content. Roux-en-Y gastric bypass rats on normal fat and no oxalate diets excreted twice as much oxalate as age matched, sham operated controls. Although Roux-en-Y gastric bypass hyperoxaluria appears primarily mediated by gut and diet, secondary causes of oxalogenesis from liver or other mechanisms deserve further exploration.

• Authors: Benjamin K Canales, Joseph Ellen, Saeed R Khan, Marguerite Hatch
• Journal: The Journal of urology (J Urol) Vol. 190 Issue 3 Pg. 1102-9 (Sep 2013) ISSN: 1527-3792 [Electronic] United States
• PMID: 23499748 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Chemical References

• Dietary Fats
• Oxalates

Topics

• Animals
• Dietary Fats (metabolism)
• Disease Models, Animal
• Feces (chemistry)
• Gastric Bypass (adverse effects, methods)
• Hyperoxaluria (etiology, physiopathology)
• Male
• Obesity (complications, surgery)
• Oxalates (metabolism)
• Postoperative Complications (epidemiology, physiopathology)
• Random Allocation
• Rats
• Rats, Sprague-Dawley
• Reference Values
• Risk Assessment
• Steatorrhea (etiology, physiopathology)
• Treatment Outcome
• Urinalysis