Bone loss after bariatric surgery: causes, consequences, and management

Abstract

Bariatric surgery is an effective and increasingly common treatment for severe obesity and its many comorbidities. The side-effects of bariatric surgery can include detrimental effects on bone and mineral metabolism. Bone disease in patients who have had bariatric surgery is affected by preoperative abnormalities in bone and mineral metabolism related to severe obesity. Changes that arise after bariatric surgery are specific to procedure type: the most pronounced abnormalities in calciotropic hormones and bone loss are noted after procedures that result in the most malabsorption. The most consistent site for bone loss after all bariatric procedures is at the hip. There are limitations of dual-energy x-ray absorptiometry technology in this population, including artefact introduced by adipose tissue itself. Bone loss after bariatric surgery is probably multifactorial. Proposed mechanisms include skeletal unloading, abnormalities in calciotropic hormones, and changes in gut hormones. Few data for fracture risk in the bariatric population are available, and this is a crucial area for additional research. Treatment should be geared toward correction of nutritional deficiencies and study of bone mineral density in high-risk patients. We explore the skeletal response to bariatric surgery, potential mechanisms for changes, and strategies for management.

Figure 1

Common Bariatric Surgery Procedures (from Atlas of Metabolic and Weight Loss Surgery, Jones et al. Cine-Med, 2010.

Figure 2

Relationship between decline in BMD at the hip (FN and TH) and extent of weight loss at 1 year after RYGB. From Fleisher et al. JCEM 2008.

Figure 3

Association between change in PTH and cortical area, cortical thickness, cortical density and total density by HR-pQCT at the tibia. From Stein et al. JCEM 2013.

Figure 4

Cumulative incidence of fracture among Olmsted County, Minnesota, residents following bariatric surgery in 1985–2004 (solid line) vs. expected incidence among community men and women (dashed line). From Nakamura et al. Osteoporosis Int 2013.