Vitamin D deficiency can be a problem after bariatric surgery because many patients have low vitamin D levels before surgery, some of the surgeries are designed to create malabsorption, and patients eat less food and different kinds of food after surgery. In the worst cases, patients may develop secondary hyperparathyroidism or bone loss, and there have been case reports of osteomalacia.
All the studies used DXA scans to assess bone density after bariatric surgery, but DXA assessment may be biased in the setting of marked weight loss because of changes in soft tissue surrounding the bones. The informal consensus among experts is that the bone density losses reported by studies are real, "but we need nonbiased methods of assessing bone mineral density" for future studies of bariatric surgery’s effects, she said.
Dr. Schafer said that she has no relevant conflicts of interest.