Weight Loss Surgery May Be Associated With Bone Loss

With the growing epidemic of obesity, many people are opting for surgical procedures to help promote weight loss. While these procedures result in significant and sustained weight loss and reverse many of the complications of obesity, this new study shows there may be harmful effects on calcium and bone metabolism.

"Our research shows that deficiencies of calcium and vitamin D absorption occur following gastric bypass surgery," said Dr. Shonni J. Silverberg, professor of medicine at Columbia University College of Physicians & Surgeons in New York, N.Y., and coauthor of the study. "When analyzing hip bone density, we found that those who lost the most weight also lost the most bone."

In this study, researchers evaluated 23 morbidly obese men and women who underwent gastric bypass surgery. Dr. Silverberg and her colleagues measured serum calcium, vitamin D, and parathyroid hormone levels before surgery and at three, six, and twelve months after surgery. Researchers also measured bone mineral density before and after surgery using dual-energy x-ray absorptiometry (DXA). One year after weight loss surgery, patients had lost an average of 99 pounds and had significant declines in hip bone mineral density (both total hip and femoral neck measurements).

"The calcium and vitamin D deficiencies may be due to the alterations in the gastrointestinal tract that take place during these procedures," said Dr. Silverberg. "These deficiencies may be restored if the amount of calcium and vitamin D supplementation is increased appropriately."

The findings from this study highlight the importance of assessing calcium sufficiency and skeletal health in the increasing numbers of individuals undergoing these procedures, said Dr. Silverberg. She adds that further studies are needed to discover how these findings relate to bone quality and fracture risk.

Other researchers working on the study include J. Fleischer, E.M. Stein, M. Della Badia, D.J. McMahon, M. Bessler, N. Restuccia, and L. Olivero-Rivera of Columbia University College of Physicians in New York, N.Y.