Impact of marked weight loss induced by bariatric surgery on bone mineral density and remodeling

Abstract

Data about the impact of bariatric surgery (BS) and subsequent weight loss on bone are limited. The objective of the present study was to determine bone mineral density (BMD), bone remodeling metabolites and hormones that influence bone trophism in premenopausal women submitted to BS 9.8 months, on average, before the study (OGg, N = 16). The data were compared to those obtained for women of normal weight (CG, N = 11) and for obese women (OG, N = 12). Eight patients in each group were monitored for one year, with the determination of BMD, of serum calcium, phosphorus, magnesium, parathyroid hormone, 25-hydroxyvitamin D, insulin-like growth factor-I (IGF-I) and osteocalcin, and of urinary calcium and deoxypyridinoline. The biochemical determinations were repeated every three months in the longitudinal study and BMD was measured at the end of the study. Parathyroid hormone levels were similar in the three groups. IGF-I levels (CG = 332 ± 62 vs OG = 230 ± 37 vs OGg = 128 ± 19 ng/ mL) were significantly lower in the operated patients compared to the non-operated obese women. Only OGg patients presented a significant fall in BMD of 6.2% at L1-L4, of 10.2% in the femoral neck, and of 5.1% in the forearm. These results suggest that the weight loss induced by BS is associated with a significant loss of bone mass even at sites that are not influenced by weight overload, with hormonal factors such as IGF-I being associated with this process.

Increased vertebral morphometric fracture in patients with postsurgical hypoparathyroidism despite normal bone mineral density

“…Although, no woman of the control group was receiving calcium and vitamin D supplementation, they exhibited normal serum levels of 25-OHD. In agreement with these results, we did not observe a high frequency of hypovitaminosis D in this region of the state of São Paulo, Brazil, in previous studies [34,35]. As vitamin D deficiency is associated with worse bone outcome, it is likely that our groups were in advantageous conditions compared to other populations with a higher incidence of vitamin D deficiency [36].…”

Bone Metabolism After Bariatric Surgery

“…(22) Several longitudinal studies lack preoperative measurements of bone density and therefore can only describe skeletal changes in the postoperative period. (24,25) Lastly, although there are a few RYGB studies that utilize more advanced bone imaging technology, (20,26,27) all studies of SG and AGB rely solely on dual-energy X-ray absorptiometry (DXA) bone density measurements that may be affected by soft tissue artifact related to weight loss (see "Controversies regarding skeletal imaging after bariatric surgery" below). With these caveats in mind, the results of metabolic bone studies in bariatric surgery patients are summarized below, by surgery type.…”

“…(29) Case reports have identified bone pain, height loss, and hypocalcemia, (30) as well as histologically confirmed osteomalacia (31) and osteitis fibrosa cystica (32) after RYGB. Numerous studies document elevated urinary and serum bone turnover markers, (17,19,20,(23)(24)(25)(26)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43) beginning as early as 3 months after surgery (19,34,35,42,43) that remain elevated throughout the second postoperative year (19,36,44) (Table 2). The typical increase in bone resorption markers far exceeds the increase in bone formation, consistent with net bone loss.…”

“…In the last decade, numerous longitudinal studies describe striking declines in bone density by DXA after RYGB (17)(18)(19)(20)(22)(23)(24)(25)(26)(33)(34)(35)39,(45)(46)(47)(48) (Table 1, Fig. 2, and Fig.…”

GLP-1 and exendin-4 can reverse hyperlipidic-related osteopenia

“…Although obesity has been traditionally considered protective for the skeleton, increasing evidence suggests otherwise. It now seems to be clear that this apparent protection is a consequence of the mechanical loading imposed by high body weight in this condition (Rosen & Bouxsein 2006, Pereira et al 2007. In fact, hypercholesterolemia appears to contribute to the pathogenesis of osteoporosis in postmenopausal women, which might justify the use of cholesterol-lowering statins as putative therapies in this situation (Herrington & Potvin Klein 2001, Tanko et al 2003, Majima et al 2007).…”