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J Urol. 2013 Sep;190(3):1102-9. doi: 10.1016/j.juro.2013.02.3229. Epub 2013 Mar 14.

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

Author information

1
Department of Urology, University of Florida, Gainesville, Florida 32610, USA. benjamin.canales@urology.ufl.edu

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.

KEYWORDS:

DIO; FM; GI; LBM; Ox; RYGB; Roux-en-Y gastric bypass; calcium oxalate; diet induced obesity; fat mass; gastric bypass; gastrointestinal; lean body mass; morbid; obesity; oxalate; steatorrhea; urinary bladder

PMID:
23499748
PMCID:
PMC3771491
DOI:
10.1016/j.juro.2013.02.3229
[Indexed for MEDLINE]
Free PMC Article
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