Small bowel resection-associated urinary calcium loss in rats on long-term total parenteral nutrition

This study was designed to study the effects of small bowel resection on daily urinary excretion patterns, plasma and bone levels of magnesium, phosphorus and calcium in rats on long-term total parenteral nutrition (TPN). Male Sprague-Dawley rats weighing 300 to 350 g were randomly divided into two groups with six rats in each group. Control consists of rats whose small intestines were transected but anastomosed. Resected rats had 70% of their small intestine removed. After intestinal resection and transection, rats were infused with a balanced TPN solution for 17 days. Resected rats excreted significantly more calcium than transected rats during the first 10 days of TPN infusion. Peak excretion occurred between day 3 and 4 followed by a trend toward a slightly higher than normal level of calcium excretion between days 10 and 17. Urinary losses of phosphorus and magnesium were not influenced by bowel resection. Plasma and tibia calcium, phosphorus and magnesium levels were not altered. The effects of small bowel resection on urinary calcium loss is specific and our data demonstrate the involvement of gut in regulating urinary calcium excretion and suggest that gut may play a significant role in TPN induced metabolic bone disease.