The impact of bariatric surgery on bone metabolism

Abstract

Purpose of review: Obesity is a worldwide epidemic. As the rate of obesity continues to soar, so too does the number of bariatric surgeries performed. Many of these surgeries achieve weight loss by limiting food intake or its absorption. The malabsorption results in an increased risk of developing calcium and vitamin D deficiencies. Whether or not this increasing population is at greater risk of osteoporosis or fractures has yet to be determined. Recent findings: A number of studies have shown that after bariatric surgery there are a number of changes in bone metabolism. Increased rates of vitamin D deficiency, secondary hyperparathyroidism, hypocalcemia, bone turnover and bone loss have all been reported. Summary: It is clear that bariatric surgery causes changes in bone metabolism. It appears that the degree of change is dependent on the amount of weight loss and malabsorption achieved. Nonsurgical weight loss and purely restrictive procedures cause moderate increases in bone turnover and moderate decreases in bone density. The procedures inducing malabsorption are associated with more significant increases in bone turnover and decreases in bone density. There is also an increased incidence of vitamin D deficiency and secondary hyperparathyroidism. Abbreviations BMC: bone mineral content; BMD: bone mineral density; BPD/DS: biliopancreatic diversion and duodenal switch; LAGB: laparoscopic adjustable gastric banding; PTH: parathyroid hormone; RYGB: Roux-en-Y gastric bypass; TFCA: true fractional calcium absorption; VBG: vertical banded gastroplasty.