Abstract
BackgroundLittle is known about changes in bone mineral density (BMD) following weight loss after one-anastomosis gastric bypass (OAGB) and the role of serum vitamin D and its supplementation on bone metabolism. We evaluated BMD after OAGB as a function of vitamin D supplementation with respect to a minimum threshold of 25-hydroxy-vitamin-D [25(OH)D] concentration, which could prevent or decelerate an eventual bone loss.MethodsFifty bariatric patients who participated in the randomized controlled trial were included in this analysis. BMD and anthropometric measurements by DXA and laboratory parameters were assessed before (T0), at 6 (T6), and 12 months (T12) after surgery.ResultsOAGB resulted in a 36% total body weight loss with a decrease in body fat and an increase in lean body mass. A significant decrease in BMD was seen in lumbar spine by 7%, left hip 13%, and total body 1%, but not in forearm. Bone turnover markers increased significantly but with normal parathyroid hormone concentrations. Weight loss was not associated with changes in BMD. A serum 25(OH)D concentration > 50 nmol/l at T6 and T12 (adequate-vitamin-D-group; AVD) showed a significant lower bone loss, compared to the inadequate-vitamin-D-group (IVD; < 50 nmol/l). Lower bone loss in the left hip showed a strong correlation with higher 25(OH)D concentrations (r = 0.635, p = 0.003).ConclusionThese findings support a dose effect of vitamin D supplementation on bone health and suggest that 25(OH)D concentrations need to be above 50 nmol/l at least during the first postoperative year to decelerate bone loss in patients undergoing OAGB.Clinical Trial Registry Number and WebsiteClinicaltrials.gov (NCT02092376) at https://clinicaltrials.gov/.EudraCT (2013-003546-16) at https://eudract.ema.europa.eu/.
Highlights
Little is known about changes in bone mineral density (BMD) following weight loss after one-anastomosis gastric bypass (OAGB)
We could demonstrate that OAGB resulted in a large reduction in body weight by 36% in morbidly obese patients with a decrease in total body fat and an increase in lean body mass
Over 12 months, a significant decrease in BMD was seen when measured in the lumbar spine (7%), left hip (13%), and in total body (1%), but not in the forearm
Summary
Little is known about changes in bone mineral density (BMD) following weight loss after one-anastomosis gastric bypass (OAGB). Low vitamin D concentrations and elevated parathyroid hormone (PTH) levels as mediators of bone loss are common findings in obese patients. Bariatric surgery affects bone metabolism by decreasing mechanical loading and subsequent reduction in the differentiation of osteoblasts [9]. Loss of adipose tissue mass and changes in anatomy and physiology of the gastrointestinal tract lead to altered hormone and adipokine secretion further affecting bone metabolism [9]. Little is known about changes in bone mineral density (BMD) following weight loss after one-anastomosis gastric bypass (OAGB) and the role of serum vitamin D and its supplementation on bone metabolism. We evaluated BMD after OAGB as a function of vitamin D supplementation with respect to a minimum threshold of 25-hydroxy-vitamin-D [25(OH)D] concentration, which could prevent or decelerate an eventual bone loss
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