Effects of jejunoileal bypass on oxalate and mineral metabolism in rats.

OBJECTIVE

To reassess the effects of jejunoileal bypass on the gastrointestinal absorption and bone metabolism of certain minerals in rats, and to see if jejunoileal bypass in rats was a suitable model in which to study formation of calcium oxalate renal stones.

DESIGN

Controlled study.

SETTING

Division of Experimental Surgery, University of Erlangen, Germany.

MATERIAL

43 male Sprague-Dawley rats.

INTERVENTION

23 rate underwent jejunoileal bypass, and 20 laparotomy, with transsection and anastomosis of the jejunum and ileotomy and suture (sham operation).

RESULTS

Rats that had undergone jejunoileal bypass ate less and gained less weight than those that had had sham operations. Absorption of calcium and phosphorus from the intestine was impaired, but that of magnesium was unchanged. Absorption of oxalate from the small intestine was unchanged, but that from the colon was increased. There were no signs of hyperoxaluria or urolithiasis. Serum mineral homeostasis was not affected by jejunoileal bypass nor were bone volume, density, or mineral concentrations. Serum concentrations of parathyroid hormone and 1,25-dihydroxycholecalciferol remained low, suggesting that jejunoileal bypass might have induced some calcium flux towards the vascular space.

CONCLUSIONS

Jejunoileal bypass halts weight increase in rats; the model may be helpful in elucidating associations between enteric factors and calciotropic hormones, and several metabolic features that are altered by jejunoileal bypass in man are not altered in rats.