Effects of weight loss on bone status after bariatric surgery: association between adipokines and bone markers

The PYY/Y2R-deficient male mouse is not protected from bone loss due to Roux-en-Y gastric bypass

BACKGROUND

Peptide YY (PYY) is an anorexigenic gut hormone that also has anti-osteogenic effects, inhibiting osteoblastic activity and inducing catabolic effects. It has been postulated that increases in PYY after Roux-en-Y gastric bypass (RYGB) contribute to declines in bone mineral density (BMD) and increases in bone turnover. The aim of this study is to determine the role of the PYY Y2-receptor in mediating bone loss post-RYGB in mice.

METHODS

We compared adult male wildtype (WT) and PYY Y2 receptor-deficient (KO) C57BL/6 mice that received RYGB (WT: n = 8; KO: n = 9), with sham-operated mice (Sham; WT: n = 9; KO: n = 10) and mice that were food-restricted to match the weights of the RYGB-treated group (Weight-Matched, WM; WT: n = 7; KO: n = 5). RYGB or sham surgery was performed at 15-16 weeks of age, and mice sacrificed 21 weeks later. We characterized bone microarchitecture with micro-computed tomography (μCT) at the distal femur (trabecular) and femoral midshaft (cortical). Differences in body weight, bone microarchitecture and biochemical bone markers (parathyroid hormone, PTH; C-telopeptide, CTX; and type 1 procollagen, P1NP) were compared using 2-factor ANOVA with Tukey's adjustments for multiple comparisons.

RESULTS

Body weights were similar in the WT-RYGB, WT-WM, KO-RYGB, and KO-WM: 41-44 g; these groups weighed significantly less than the Sham surgery groups: 55-57 g. Trabecular BMD was 31-43 % lower in RYGB mice than either Sham or WM in WT and KO groups. This deficiency in trabecular bone was accompanied by a lower trabecular number (19 %-23 %), thickness (22 %-30 %) and increased trabecular spacing (25 %-34 %) in WT and KO groups (p < 0.001 for all comparisons vs. RYGB). RYGB led to lower cortical thickness, cortical tissue mineral density, and cortical bone area fraction as compared to Sham and WM in WT and KO groups (p ≤ 0.004 for all). There were no interactions between genotype and bone microarchitecture, with patterns of response to RYGB similar in both WT and KO groups. CTX and P1NP were significantly higher in RYGB mice than WM in WT and KO groups. PTH did not differ among groups.

CONCLUSIONS

RYGB induced greater trabecular and cortical deficits and high bone turnover than observed in weight-matched mice, with a similar pattern in the WT and Y2RKO mice. Thus, skeletal effects of RYGB are independent of weight loss, and furthermore, PYY signaling through Y2R is not a key mediator of bone loss post-RYGB.

Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on Bone Mineral Density in Zucker Diabetic Fatty Rats: A Short-Term Comparative Study

BACKGROUND

While bariatric surgery could result in weight loss as well as glycaemia improvement, the short-term impact on bone health in a high glycemic environment following Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) remains intriguing.

OBJECTIVE

The aim of this study was to compare the short-term effects of RYGB and SG procedures on bone health in Zucker diabetic fatty (ZDFfa/fa) rats.

METHODS

Thirty age-matched male ZDFfa/fa rats were randomized into RYGB, SG, and sham groups after establishment of the diabetic model. Body weight, blood glucose, bone mineral density (BMD), the level of bone turnover markers (BTM), vitamin D, and serum calcium and phosphorus were measured 4 weeks after the operation.

RESULTS

The RYGB procedure brought about lower blood glucose, BMD, serum calcium and phosphorus levels, as well as a relatively higher bone turnover rate and 1,25(OH)2VD level, compared to the SG and sham groups, while the influences of the SG procedure were not significant. 25(OH)VD demonstrated no significant difference among the 3 groups.

CONCLUSIONS

Despite its excellent ability to provide short-term glycemic control, the RYGB procedure could led to more severe impairment of bone health compared to the SG procedure. Bone health should be procured after bariatric surgery, especially with the RYGB procedure. Early detection of BMD and BTM may help to avoid deterioration of bone.

Barocrinology: The Endocrinology of Obesity from Bench to Bedside

Obesity has reached pandemic proportions. Hormonal and metabolic imbalances are the key factors that lead to obesity. South Asian populations have a unique phenotype, peculiar dietary practices, and a high prevalence of consanguinity. Moreover, many lower middle-income countries lack appropriate resources, super-specialists, and affordability to manage this complex disorder. Of late, there has been a substantial increase in both obesity and diabesity in India. Thus, many more patients are being managed by different types of bariatric procedures today than ever before. These patients have many types of endocrine and metabolic disturbances before and after bariatric surgery. Therefore, these patients should be managed by experts who have knowledge of both bariatric surgery and endocrinology. The authors propose “Barocrinology”, a novel terminology in medical literature, to comprehensively describe the field of obesity medicine highlighting the role of knowing endocrine physiology for understating its evolution, insights into its complications and appreciating the changes in the hormonal milieu following weight loss therapies including bariatric surgery. Barocrinology, coined as a portmanteau of “baro” (weight) and endocrinology, focuses upon the endocrine and metabolic domains of weight physiology and pathology. This review summarizes the key pointers of bariatric management from an endocrine perspective.

Bariatric Surgery: Remission of Inflammation, Cardiometabolic Benefits, and Common Adverse Effects

Obesity is associated with increased mortality as a result of several comorbidities which occur in tandem with the obese state. Chronic inflammation is well documented in obesity, and evidence from numerous studies support the notion that the increased inflammation in individuals with obesity accentuates the comorbidities seen in this condition. The remission of comorbidities such as metabolic, cardiovascular, and neurological complications occurs following bariatric procedures. Bariatric surgery significantly reduces mortality and results in remarkable weight loss and reversal in several obesity-related comorbidities. There is indisputable evidence that the resolution of inflammation that occurs after bariatric surgery mitigates some of these comorbidities. With the increasing use of bariatric surgery for the treatment of severe obesity, it is pivotal to elucidate the underlying mechanisms responsible for the notable improvements seen after the procedure. This review summarizes underlying mechanisms responsible for the remission of obesity-related abnormalities and discusses the common adverse effects of bariatric surgery. Well-stratified, large-scale studies are still needed for a proper evaluation of these underlying mechanisms.

Association of Bariatric Surgery With Risk of Fracture in Patients With Severe Obesity

IMPORTANCE

Given the complex relationship between body mass index, body composition, and bone density and the correlative nature of the studies that have established the prevailing notion that higher body mass indices may be protective against osteopenia and osteoporosis and, therefore, fracture, the absolute risk of fracture in patients with severe obesity who undergo either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) compared with those who do not undergo bariatric surgery is unknown.

OBJECTIVE

To assess the rates of fractures associated with obesity and compare rates between those who do not undergo bariatric surgery, those who undergo RYGB, and those who undergo SG.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective multicenter cohort study of Medicare Standard Analytic Files derived from Medicare parts A and B records from January 2004 to December 2014, patients classified as eligible for bariatric surgery using the US Centers of Medicare & Medicaid criteria who either did not undergo bariatric surgery or underwent RYGB or SG were exactly matched in a 1:1 fashion based on their age, sex, Elixhauser Comorbidity Index, hypertension, smoking status, nonalcoholic fatty liver disease, hyperlipidemia, type 2 diabetes, osteoporosis, osteoarthritis, and obstructive sleep apnea status. Data were analyzed from November to December 2019.

EXPOSURES

RYGB or SG.

MAIN OUTCOMES AND MEASURES

The primary outcome measured in this study was the odds of fracture overall based on exposure to bariatric surgery. Secondary outcomes included the odds of type of fracture (humerus, radius or ulna, pelvis, hip, vertebrae, and total fractures) based on exposure to bariatric surgery.

RESULTS

A total of 49 113 patients were included and were equally made up of 16 371 bariatric surgery-eligible patients who did not undergo weight loss surgery, 16 371 patients who had undergone RYGB, and 16 371 patients who had undergone SG. Each group consisted of an equal number of 4109 men (25.1%) and 12 262 women (74.9%) and had an equal distribution of ages, with 11 780 patients (72.0%) 64 years or younger, 4230 (25.8%) aged 65 to 69 years, 346 (2.1%) aged 70 to 74 years, and 15 (0.1%) aged 75 to 79 years. Patients undergoing RYGB were found to have no significant difference in odds of fractures compared with bariatric surgery-eligible patients who did not undergo surgery. Patients undergoing undergone SG were found to have decreased odds of fractures of the humerus (odds ratio [OR], 0.57; 95% CI, 0.45-0.73), radius or ulna (OR, 0.38; 95% CI, 0.25-0.58), hip (OR, 0.49; 95% CI, 0.33-0.74), pelvis (OR, 0.34; 95% CI, 0.18-0.64), vertebrae (OR, 0.60; 95% CI, 0.48-0.74), or fractures in general (OR, 0.53; 95% CI, 0.46-0.62). Compared with patients undergoing SG, patients undergoing RYGB had a significantly greater risk of total fractures (OR, 1.79; 95% CI, 1.55-2.06) and humeral fractures (OR, 1.60; 95% CI, 1.24-2.07).

CONCLUSIONS AND RELEVANCE

In this cohort study, bariatric surgery was associated with a reduced risk of fracture in bariatric surgery-eligible patients. Sleeve gastrectomy might be the best option for weight loss in patients in which fractures could be a concern, as RYGB may be associated with an increased fracture risk compared with SG.

Determining changes in bone metabolism after bariatric surgery in postmenopausal women

BACKGROUND

Accelerated bone loss is a known complication after bariatric surgery. Bone mineral density has been shown to decrease significantly after Laparoscopic Roux-en-Y gastric bypass (RYGB). Laparoscopic sleeve gastrectomy (SG) effects on bone density are largely unknown. This should be considered for those with increased preoperative risk for bone loss, such as postmenopausal females.

METHODS

This prospective clinical trial included postmenopausal patients, with BMI ≥ 35 k/m2, being evaluated for either RYGB or SG. Patients with history of osteoporosis, estrogen hormone replacement therapy, active smoking, glucocorticoid use, or weight > 295 lb were excluded. Patients underwent DEXA scans preoperatively and 1 year postoperatively with measurement of total body bone mineral density (BMD) and bone mineral content (BMC) as well as regional site-specific BMD and BMC.

RESULTS

A total of 28 patients were enrolled. 16 (57.1%) patients underwent RYGB and 12 (42.9%) patients underwent SG. Median preoperative BMI was 44.2 k/m2 (IQR 39.9, 46.6). Median change in BMI at 12 months was - 11.3 k/m2 (IQR - 12.8, - 7.9). A significant reduction in total body BMC was seen when comparing preoperative measurements to postoperative measurements (2358.32 vs 2280.68 grams; p = 0.002). Regional site BMC and BMD significantly decreased in the ribs and spine postoperatively (p = < 0.02) representing the greatest loss in the axial skeleton. Comparing those who underwent RYGB to SG there was no significant difference between the two groups when evaluating changes in total or regional site BMD.

CONCLUSION

Postmenopausal women were found to have decreased BMD and BMC after RYGB and SG, suggesting that high-risk women may benefit from postoperative DEXA screening. Further study is needed to determine the clinical significance of these findings. It is unknown if these changes in BMD are due to modifiable factors (Vitamin D level, activity level, hormone status, etc.), and whether BMD and BMC is recovered beyond 1 year.

Unacylated ghrelin is correlated with the decline of bone mineral density after Roux-en-Y gastric bypass in obese Chinese with type 2 diabetes

BACKGROUND

Bariatric surgery is an effective and therapeutic way for different metabolic diseases. It has become a focus of attention about the effects and molecular mechanisms to bone metabolism.

OBJECTIVE

We aim to assess the changes of bone mineral density (BMD) among Chinese obese individuals with type 2 diabetes who have undergone Roux-en-Y gastric bypass surgery (RYGB). Two ghrelin gene products, namely unacylated ghrelin (UAG) and obestatin, were evaluated the roles in this pathologic process.

SETTING

University-affiliated hospital, China.

METHODS

Thirty patients who had received RYGB were enrolled in the study. Changes in anthropometric parameters, metabolic indexes, and serum UAG and obestatin were assessed preoperatively, 6, 12, and 24 months postoperatively. BMD at lumbar spine (LS), femoral neck (FN), and total hip (TH) were identified.

RESULTS

RYGB resulted in statistical reductions of BMD in 3 different skeletal parts. After the first 6 months, BMD began to reduce and maintained a declining trend until 24 months postoperatively. Comparing to baseline, the maximal reduction of BMD was as high as 10.28% in total hip. The plasma concentration of UAG increased after 6 months (51.61 ± 55.21 versus 71.95 ± 64.91 pg/mL; P < .01), as well as the serum obestatin level (1.65 ± 0.88 versus 1.71 ± 0.99 ng/mL; P > .05). Although there was a slight drop of both peptides in the first year, they were still above the baseline. Notably, in the second year, UAG and obestatin rose to their peak values, respectively (91.90 ± 77.11 pg/mL and 1.74 ± 1.09 ng/mL). There was a negative correlation between UAG and BMD in all sites. Multiple linear regression analysis showed that the UAG level was the independent parameter associated with BMD at baseline (FN: β = -.407, P = .012 and TH: β = -0.396, P = .030 respectively), as well as the changes of UAG that were independently related with reduction percentage of LS BMD after 24 months (β = - .379, P = .046).

CONCLUSION

The reduction of BMD in obese Chinese with type 2 diabetes was observed after RYGB. The pronounced increase of serum UAG acts as an independent risk factor for the decrease of BMD.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

Thin bones: Vitamin D and calcium handling after bariatric surgery

Bariatric surgery has proven to be a valuable treatment option for morbid obesity. However, these procedures can lead to impaired intestinal absorption of calcium and vitamin D, thereby challenging calcium homeostasis and possibly contributing to bone loss leading to an increased fracture risk. Besides calcium and vitamin D malabsorption, hormonal changes occurring after surgery can also be the source of observed bone loss. In this review, first, a case report will be discussed, highlighting the relevance of this topic. Afterwards, changes in bone density and fracture risk, after the two most performed types of bariatric surgery, Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) will be discussed. In addition, we discuss the putative underlying mechanisms leading to bone changes based on both preclinical and clinical observations. Nonetheless, it is clear further research is needed to further elucidate the exact mechanisms of bone loss following bariatric surgery and subsequently identify potential treatment options for bone preservation.

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Bariatric surgery induces bone loss and leads to increased fracture risk.

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Bone resorption increases after both SG and, more strongly, after RYGB.

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Malabsorption and adipose tissue-related hormones likely contribute to bone loss.

The Effect of a Muscle Weight-Bearing and Aerobic Exercise Program on the Body Composition, Muscular Strength, Biochemical Markers, and Bone Mass of Obese Patients Who Have Undergone Gastric Bypass Surgery

BACKGROUND

The effect of an exercise program on the body composition, muscular strength (MS), biochemical markers, and bone mineral density (BMD) of individuals undergoing gastric bypass is unclear. We assessed lean mass (LM), MS, bone remodeling markers, and BMD before and after supervised weight-bearing and aerobic exercise training in obese patients who underwent Roux-en-Y gastric bypass (RYGB).

METHODS

This study included 37 obese patients (81.1% women, mean age 38.2 years, mean body mass index 42.4 ± 0.5 kg/m²). Whole body densitometry was used to evaluate pre- and postoperative BMD, total body fat, and LM. Serum calcium, parathyroid hormone, 25-hydroxyvitamin D, and bone remodeling markers were measured. MS was determined through the concentric 10 repetition maximum test. Postoperatively, participants were divided into two groups: the training group, who followed an exercise program (TG, n = 18), and the control group, who did not (CG, n = 19).

RESULTS

After 1 year, the TG showed a lower decrease in total BMD and at the lumbar spine and right hip compared with the CG (p < 0.001). The TG had lower mass reduction and an increase in upper limb LM compared with the CG (both p < 0.05). There was no significant difference between groups in bone markers or calcium metabolism. MS was higher in the TG than the CG (p < 0.05).

CONCLUSION

The supervised exercise program attenuated lumbar spine and right hip BMD loss and improved LM in the arms and overall MS but did not affect bone remodeling.

Outcomes of laparoscopic sleeve gastrectomy in elderly obese Japanese patients

AIM

Laparoscopic sleeve gastrectomy (LSG) has proven to be the most effective strategy for the treatment of morbid obesity, however its efficacy and safety in an aging population has not yet been confirmed. In this study, we evaluated the effectiveness and safety of LSG in elderly obese Japanese patients.

METHODS

Three obese individuals aged >60 years and 11 obese individuals aged <60 years who underwent LSG were enrolled. Pre- and postoperative changes after at least 12 months were examined, including bodyweight, body mass index, total weight loss, excess weight loss, bone mineral density and bone-related markers.

RESULTS

There were no significant differences between patients aged <60 years and >60 years in terms of percent total weight loss (24.4 ± 11 vs 23 ± 4.4%, respectively) and percent excess weight loss (49.1 ± 23.4 vs 47.6 ± 10 %, respectively). Dual-energy X-ray absorptiometry was carried out before and 12 months after LSG. There were no significant differences in bone mineral density changes at the lumbar spine and femoral neck between the two groups (0.01 ± 0.06 vs 0.02 ± 0.03 g/cm² , -0.03 ± 0.06 vs -0.08 ± 0.02 g/cm² , respectively). There were no peri- and postoperative complications. All three patients aged >60 years had reduced bone mineral density in the femoral neck after LSG; one was diagnosed with osteoporosis.

CONCLUSIONS

Although the present results suggest that LSG could be of considerable benefit to elderly obese Japanese patients, long-term careful observation after bariatric surgery is especially important in elderly patients to prevent future osteoporosis. Geriatr Gerontol Int 2017; 17: 2068-2073.

Changes in bone metabolism after bariatric surgery by gastric bypass or sleeve gastrectomy

Bariatric surgery results in rapid weight loss and beneficial metabolic effects, but may have negative effects on the skeleton. The objective of this prospective study was to evaluate changes in bone metabolism in response to bariatric surgery with two surgical techniques. 46 morbidly obese subjects (mean 44.9years, BMI 42.1) with (n=19) or without (n=27) type 2 diabetes (T2DM) at baseline underwent either Roux-en-Y gastric bypass (RYGB, n=21) or sleeve gastrectomy (SG, n=25). Bone turnover markers (CTX, PINP, TRAcP5b, TotalOC and ucOC) were measured before and six months after surgery. Volumetric bone mineral density (vBMD) at lumbar spine and vertebral bone marrow (VBM) fat were measured in 21 subjects (7 RYGB and 14 SG) with three-dimensional quantitative computer tomography and ¹H MR spectroscopy, respectively. 25 non-obese subjects were recruited as controls (mean 45.8years, BMI 23.0) and assessed at a single cross-sectional visit. Obese subjects had significantly lower bone turnover at baseline when compared to non-obese controls. Bone metabolic markers markedly increased post-operatively (p<0.0001 for all). The activation of bone remodeling was significantly higher after RYGB than after SG and was particularly observed in patients, whose type 2 diabetes was in remission after weight loss. There was no change in volumetric BMD or marrow fat at lumbar spine six months after surgery in our sample. In conclusion, severe obesity decreases bone remodeling, which is activated after bariatric surgery. The increase in bone turnover after surgery is affected by the choice of surgical technique and by the post-surgery remission of T2DM.

Long-term effects of a very-low-carbohydrate weight-loss diet and an isocaloric low-fat diet on bone health in obese adults

OBJECTIVE

Compromised bone health is a frequently cited concern of very-low-carbohydrate (LC) diets, although limited data are available from long-term, well-controlled, randomized studies. This study compared the effects of an energy-restricted LC diet and traditional, higher-carbohydrate, low-fat (LF) diet on bone health after 12 mo.

METHODS

One hundred eighteen abdominally obese adults were randomized to consume either an energy-restricted (∼6-7 MJ/d [∼1450-1650 kcal/d]), planned isocaloric LC, or LF diet for 12 mo. Body weight, total body bone mineral content and bone mineral density (BMD), and serum bone crosslaps were assessed pre- and postintervention.

RESULTS

Sixty-five participants completed the study (LC = 32, LF = 33; age: 51.3 ± 7.1 y; BMI: 33.4 ± 4.0 kg/m(2)). Weight loss was similar in both groups (LC: -14.5 ± 9.8 kg, LF: -11.7 ± 7.3 kg; P = 0.26). By 1 y, total body bone mineral content had not changed in either group (LC: 2.84 ± 0.47 to 2.88 ± 0.49 kg, LF: 3.00 ± 0.52 to 3.00 ± 0.51 kg; P = 0.07 time × diet effect). In both groups, total body BMD decreased (LC: 1.26 ± 0.10 to 1.22 ± 0.09 g/cm(2), LF: 1.26 ± 0.09 to 1.23 ± 0.08 g/m(2); P < 0.001 time) and bone serum crosslaps increased (LC: 319.3 ± 142.6 to 396.5 ± 172.0 ng/L, LF: 276.3 ± 100.6 to 365.9 ± 154.2 ng/L; P < 0.001 time) independent of diet composition (P ≥ 0.25 time × diet effect). Future studies would be strengthened by the assessment of regional BMD at clinically relevant sites (i.e., hip and spine) and multiple markers of bone turnover.

CONCLUSIONS

Weight loss following a hypocaloric LC diet compared with an LF diet does not differentially affect markers of bone health over 12 mo in overweight and obese adults.

Effects of omega-loop gastric bypass on vitamin D and bone metabolism in morbidly obese bariatric patients

BACKGROUND

Bariatric patients often suffer from nutrient deficiencies. Little is known about vitamin D levels and bone metabolism in patients undergoing omega-loop gastric bypass (OLGB). We, therefore, evaluated parameters of vitamin D metabolism preoperatively and during the first postoperative year.

METHODS

Within our cohort study, we retrospectively evaluated the respective parameters pre-, 3, 6, and 12 months postoperatively in patients with OLGB, between February 2011 and February 2013.

RESULTS

In patients [n = 50; age 46 (15) years, mean (SD); 12 male, 38 female] BMI was 45.4 (6.6) kg/m(2) preoperatively and decreased to 29.1 (3.8) kg/m(2) after 12 months, corresponding to a total body weight loss of 36 %. Preoperatively, the prevalence of vitamin D deficiency was 96 and 30 % demonstrated elevated parathyroid hormone yielding a prevalence of secondary hyperparathyroidism of 17 %. Postoperatively, subjects received individually adjusted vitamin D3 supplementation (95 % CI 200-3000 IU/day), according to the available guidelines at that time. Nevertheless, every third patient was vitamin D deficient at 12 months (80 %). In patients with preoperative BMI >45 vs. <45 kg/m(2), we observed a 3-fold higher risk for vitamin D deficiency over 12 months [OR = 3.10, 95 % CI (1.01-9.51), p = 0.048].

CONCLUSIONS

To avoid vitamin D deficiency, morbidly obese patients, particularly those with higher preoperative BMI, should be regularly screened pre- and postoperatively. Standard postsurgical supplementation has not been adequate to restore 25-OHD status and current guidelines are not very specific in terms of timing and dosing of vitamin D3 supplementation. Consequently, further trials to enhance the evidence on vitamin D supplementation are warranted.

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status

Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.

Changes in bone mineral density after sleeve gastrectomy or gastric bypass: relationships with variations in vitamin D, ghrelin, and adiponectin levels

BACKGROUND

A major long-term concern after gastric bypass (GBP) is the risk of osteoporosis; however, little is known about this complication in patients undergoing sleeve gastrectomy (SG).

OBJECTIVE

To evaluate changes in bone mineral density (BMD) after GBP and SG, and its relationship with changes in vitamin D, parathyroid hormone (PTH), ghrelin, and adiponectin.

METHODS

Twenty-three women undergoing GBP (BMI 42.0 ± 4.2 kg/m2; 37.3 ± 8.1 years) and 20 undergoing SG (BMI 37.3 ± 3.2 kg/m2; 34.2 ± 10.2 years) were studied before and 6 and 12 months after surgery. BMD was measured by dual-energy X-ray absorptiometry. Plasma PTH, 25-hydroxyvitamin D (25-OHD), ghrelin, and adiponectin concentrations were determined. Food as well as calcium and vitamin D supplement intake was recorded.

RESULTS

Excess weight loss (mean ± SE), adjusted by baseline excess weight, was 79.1±3.8% and 74.9 ± 4.1% 1 year after GBP and SG, respectively (p = 0.481). Significant reduction in BMD for total body (TB), lumbar spine (LS), and femoral neck (FN) was observed after GBP. In the SG group, reduction in BMD was significant only for TB. Adjusted by baseline BMD, the difference between change in BMD for GBP vs. SG was not significant for TB, LS, or FN. Percent reduction in ghrelin concentration was a main factor related to total BMD loss (GBP group) and LS BMD loss (GBP and SG groups).

CONCLUSIONS

One year after gastric bypass, bone mineral density was significantly affected, mainly at the femoral neck. Decreases in bone mineral density were more dramatic among patients who had greater baseline BMD and greater reduction in ghrelin concentrations.

Skeletal effects of bariatric surgery: examining bone loss, potential mechanisms and clinical relevance

Bariatric surgery is the most effective therapeutic approach to morbid obesity, resulting in substantial weight loss and improved cardiometabolic profiles; however, a growing body of evidence suggests that bariatric procedures increase both skeletal fragility and the risk of related future fracture secondary to excessive bone loss. Prospective evidence shows that areal bone mineral density (BMD) assessed by dual energy X-ray absorptiometry (DXA) declines by as much as 14% in the proximal femoral regions, including the femoral neck and total hip, 12 months postoperatively. Lumbar spine areal BMD outcomes show greater 12-month postoperative variability across surgical procedures (-8 to +6%) and contrast with no change in volumetric BMD outcomes measured by quantitative computed tomography. Diminished mechanical loading, micronutrient deficiency and malabsorption, along with neurohormonal alterations, offer plausible underlying mechanisms to explain these observed post-bariatric bone changes, but most remain largely unsubstantiated in this population. Importantly, DXA-based skeletal imaging may have limited utility in accurately detecting bone change in people undergoing bariatric surgery; partly because excessive tissue overlying bone increases the variability of areal BMD outcomes. Moreover, a paucity of fracture and osteoporosis incidence data raises questions about whether marked post-bariatric surgery bone loss is clinically relevant or a functional adaptation to skeletal unloading. Future studies that use technology which is able to accurately capture the site-specific volumetric BMD and bone architectural changes that underpin bone strength in people undergoing bariatric surgery, that consider mechanical load, and that better quantify long-term fracture and osteoporosis incidence are necessary to understand the actual skeletal effects of bariatric surgery.

Effect of weight loss on bone mineral density determined by ultrasound of phalanges in obese women after Roux-en-y gastric bypass: conflicting results with dual-energy X-ray absorptiometry

The rapid weight loss that occurs in obese patients submitted to Roux-en-y gastric bypass (RYGB) as well as the changes in dietary pattern and the intestinal malabsorption result in changes in bone mineral density (BMD). The objective of the present study was to assess the changes in BMD after the weight loss induced by RYGB using ultrasound of the phalanges and compare the results with those obtained by dual-energy X-ray absorptiometry (DXA). We conducted a 1-yr prospective longitudinal study on women with grade III obesity submitted to RYGB. Anthropometric (weight, height, body mass index, and abdominal circumference) and body composition measurements by electrical bioimpedance, assessment of food consumption by 24-h recall, biochemical evaluation, and assessment of BMD by ultrasonography of the phalanges and DXA (BMD values are from the 33% radius site) were performed during the preoperative period and 3, 6, and 12 mo after surgery. The mixed-effects linear regression model was used to analyze the effect of postoperative time on the variable of interest, and the kappa coefficient (p < 0.05) was used to compare the concordance of the methods used for BMD evaluation. Twenty-nine patients were included in the study. During the 1-yr follow-up, a reduction of 39 ± 8 kg (71 ± 15% of excess weight) and 29 ± 7 kg of fat mass was observed. Calcium and zinc concentrations were reduced after 12 mo. No difference in caffeine, calcium, or sodium consumption was observed between the preoperative and postoperative periods. Analysis of BMD by ultrasonography of the phalanges 1 yr after surgery showed increased values of amplitude-dependent speed of sound (2064.6 ± 59.4 vs 2154.7 ± 63 m/s; p < 0.001) and ultrasound bone profile index (0.73 ± 0.13 vs 0.76 ± 0.14; p < 0.001). Analysis of BMD by DXA showed a reduction of BMD values (0.6 ± 0.04 vs 0.57 ± 0.05 g/cm³; p < 0.001) in the sixth month and maintenance of the values from the sixth to the 12th month. At the end of the study, there was no concordance between the methods for BMD analysis. This study showed improvement in bone quality and quantity assessed by ultrasonography. However, the DXA results showed a reduction in BMD after 12 mo of RYGB. Thus, the BMD measurement methods were discordant.

Bone metabolism after bariatric surgery

Bariatric surgery is a popular and effective treatment for severe obesity but may have negative effects on the skeleton. This review summarizes changes in bone density and bone metabolism from animal and clinical studies of bariatric surgery, with specific attention to Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG). Skeletal imaging artifacts from obesity and weight loss are also considered. Despite challenges in bone density imaging, the preponderance of evidence suggests that bariatric surgery procedures have negative skeletal effects that persist beyond the first year of surgery, and that these effects vary by surgical type. The long-term clinical implications and current clinical recommendations are presented. Further study is required to determine mechanisms of bone loss after bariatric surgery. Although early studies focused on calcium/vitamin D metabolism and mechanical unloading of the skeleton, it seems likely that surgically induced changes in the hormonal and metabolic profile may be responsible for the skeletal phenotypes observed after bariatric surgery.

Interrelationship among muscle, fat, and bone: connecting the dots on cellular, hormonal, and whole body levels

While sarcopenia and sarcopenic obesity have been recognized in the last decade, a combined concept to include decreased muscle mass and strength, as well as decreased bone mass with coexistence of adiposity is discussed here. We introduce a new term, osteopenic obesity, and operationalize its meaning within the context of osteopenia and obesity. Next, we consolidate osteopenic obesity with the already existing and more familiar term, sarcopenic obesity, and delineate the resulting combined condition assigning it the term osteosarcopenic obesity. Identification and possible diagnosis of each condition are discussed, as well as the interactions of muscle, fat and bone tissues on cellular level, considering their endocrine features. Special emphasis is placed on the mesenchymal stem cell commitment into osteoblastogenic, adipogenic and myogenic lineages and causes of its deregulation. Based on the presented evidence and as expounded within the text, it is reasonable to say that under certain conditions, osteoporosis and sarcopenia could be the obesity of bone and muscle, respectively, with the term osteosarcopenic obesity as an encompassment for all.

Short- and mid-term changes in bone mineral density after laparoscopic sleeve gastrectomy

BACKGROUND

Bariatric surgery is the most effective treatment for achieving a significant weight loss. Morbidities present a significant reduction after bariatric surgery, but it may also result in several health complications, related to nutritional deficiencies, including bone metabolism. Several studies have reported a decrease in bone mineral density (BMD), but most of them referring to malabsorptive procedures. Restrictive procedures do not imply changes in gastrointestinal anatomy, so that one may expect fewer metabolic disturbances.

METHODS

We performed a retrospective observational study of all morbidly obese patients undergoing LSG between 2008 and 2011 at our institution. Bone densitometry was performed before surgery and 1 and 2 years after the intervention. Body size measurements, analytical variables and densitometric values in the lumbar spine (BMD, t score and z score) were investigated.

RESULTS

Forty-two patients were included, 39 females and 3 males. Mean BMI was 51.21 kg/m(2). Mean excessive BMI loss was 79.9 % after 1 year and 80.6 % after 2 years. Mean BMD values for spine increased progressively, reaching statistical significance at 1 and at 2 years. Percentage of BMD increase was 5.7 % at 1 year and 7.9 % at 2 years. An inverse correlation was observed between BMD increase and parathyroid hormone (PTH) decrease and a direct correlation between BMD and vitamin D increase.

CONCLUSION

Bone mineral density showed a progressive increase during the first and second year after sleeve gastrectomy. BMD changes are not associated with weight loss, but showed a direct correlation with vitamin D and an inverse correlation with PTH levels.

Gastric bypass in obese rats causes bone loss, vitamin D deficiency, metabolic acidosis, and elevated peptide YY

BACKGROUND

Metabolic bone disease and bariatric surgery have long been interconnected. The objective of this study is to better understand the mechanisms of bone mass loss after Roux-en-Y gastric bypass (RYGB) surgery. We evaluated mineral homeostasis and bone mass in diet-induced obese (DIO) rats after RYGB or sham surgery.

METHODS

Twelve DIO male Sprague Dawley rats underwent RYGB (n = 8) or sham (n = 4) surgery at 21 weeks of age. Postoperatively, animals ate an ad libitum 40% fat, normal calcium diet and were euthanized 22 weeks later. Serum and urine chemistries, insulin, leptin, bone turnover markers (BTM), and calciotropic and gut hormones were measured before and 22 weeks after surgery. Femurs were analyzed using microcomputed tomography (µCT).

RESULTS

Compared to sham, RYGB animals had lower serum bicarbonate, calcium, 25-hydroxyvitamin D, insulin, and leptin levels with higher serum parathyroid hormone, peptide YY, and urinary calcium at 43 weeks of age. Sham control rats gained weight and had coupled decreases in formation (P1NP and OC) and unchanged resorption (CTX) BTMs. Comparatively, RYGB animals had higher serum CTX and OC but even lower P1NP levels than controls. µCT revealed lower trabecular bone volume, number, and thickness and lower cortical bone volume, thickness, and moment of inertia relative to controls.

CONCLUSION

In rats with DIO, long-term RYGB-associated bone resorption appears to be driven in part by vitamin D malabsorption and secondary hyperparathyroidism. Other mechanisms, such as chronic acidosis, changes in fat-secreted hormones, and persistently elevated gut-derived hormone peptide YY, may also contribute to observed bone mass differences. Further investigation of these potential contributors to bone loss may lead to new targets for skeletal maintenance after RYGB.

[Changes in bone metabolism markers in women after Roux-en-Y gastric bypass]

OBJECTIVE

To evaluate bone turnover markers and bone mineral density (BMD) in women after Roux-en-Y (RYGB) gastric bypass.

SUBJECTS AND METHODS

In a cross-sectional study, 48 women post-RYGB after three years, and 41 healthy women were evaluated.

EVALUATIONS

body mass index (BMI); physical activity; food intake; serum levels of calcium, phosphorus, magnesium, alkaline phosphatase, C-terminal telopeptide (CTX), intact parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), osteocalcin, urinary calcium and BMD.

RESULTS

Significantly higher levels were observed for osteocalcin (p < 0.001), CTX (p < 0.001), and PTH (p < 0.001) in the RYGB group when compared with the control group; 25OHD deficiency/insufficiency was more frequent in the RYGB group (p = 0.010), even after adjusted for nutritional status, and it was associated with secondary hyperparathyroidism (p = 0.025); there was no difference in BMD between the groups. Energy (p = 0.036) and protein intake (p = 0.004) were lower in the RYGB group.

CONCLUSION

Patients submitted to RYGB showed a significantly higher frequency of vitamin D deficiency, secondary hyperparathyroidism, and increase in bone remodeling markers, with no difference in BMD status.

[Bariatric surgery - significance, risks, long term consequences]

In recent years the number of bariatric surgery has markedly increased in industrial nations. Surgery provides a more rapid decrease of body weight than conservative approach. However a long term conservative follow up therapy is mandatory to stabilize reduced weight. Due to increasing knowledge from long term follow up of surgically treated obese patients there is a growing body of evidence that frequently there is necessity of reoperations and of substitution both of trace elementsand of minerals or vitamins due to their hampered enteral resorption. Additionally therapy of surgery induced endocrine alterations not seldom is necessary.These insights are of outstanding importance because meanwhile an enlargement of the indications for bariatric surgery as a therapeutic option for metabolic disorders is being discussed. This review refers to the recent internationally published papers concerning consequences of bariatric surgery.

Bone mineral changes in spine and proximal femur in individual obese women after laparoscopic sleeve gastrectomy: a short-term study

BACKGROUND

The aim of the study was to establish longitudinal bone changes in obese women after laparoscopic sleeve gastrectomy (LSG).

METHODS

Twenty-nine women at baseline mean age of 40.41 ± 9.26 years and with mean body mass index (BMI) of 43.07 ± 4.99 kg/m(2) were included in a 6-month study. Skeletal status at hip [femoral neck (FN) and total hip (TH)] and spine was assessed at baseline, as well as in 3 and 6 months after surgery. Body size was measured at baseline and follow-up (weight, height, BMI, and waist).

RESULTS

Baseline body weight was 117.5 ± 18.4 kg. The mean body weight and BMI decreased by 17.9 % during the first 3 months after surgery to obtain 28.4 % after 6 months. At 6 months, BMD decreased significantly for spine by 1.24 %, FN 6.99 %, and TH 5.18 %. The changes after 3 months in individual subjects showed that, in the majority of subjects, FN and TH BMD decreased significantly (in 52 % and 69 % of subjects, respectively), and in 24 % loss of BMD was found at the spine. After 6 months, the corresponding, significant decreases in individual subjects were found in 72 %, 86 %, and 38 % of woman, respectively. Those with a significant loss of FN BMD tended to lose more weight (30 ± 9.47 versus 23.25 ± 6.08 kg, p = 0.061) than others; women with a significant decrease of FN BMD lost more weight than those with no such decrease (30.43 ± 8.07 versus 15 ± 1.91 kg).

CONCLUSION

LSG proved efficient for body weight reduction, however, with a parallel decline in bone mineral density.

The prolonged survival of fibroblasts with forced lipid catabolism in visceral fat following encapsulation in alginate-poly-L-lysine

Although alginate-poly-L-lysine (AP(L)) encapsulation of cells producing bioactive peptides has been widely tested, it is unknown whether AP(L) supports lasting catabolic functions of encapsulated cells in adipose tissue, which are required for obesity reduction. We tested functions of AP(L)-encapsulated fibroblasts isolated from wild-type (WT) and aldehyde dehydrogenase 1a1 knockout mice (KO), which resist obesity on a high-fat (HF) diet, have a higher metabolic rate, and express increased levels of thermogenic uncoupling protein-1 (Ucp1) in their deleterious visceral fat depots compared to WT mice. To enable in vivo detection and quantification, fibroblasts were stably transfected with green-fluorescent protein. WT- or KO-containing microcapsules were injected into two visceral depots of WT mice fed an HF diet. Eighty days after transplantation, microcapsules were located in vivo using magnetic resonance imaging. KO microcapsules prevented weight gain in obese WT mice compared to a mock- and WT capsule-injected groups on an HF diet. The weight loss in KO-treated mice corresponded to lipid reduction and induction of thermogenesis in the injected visceral fat. The non-treated subcutaneous fat was not altered. Our data suggest that the AP(L) polymer supports long-term catabolic functions of genetically-modified fibroblasts, which can be potentially used for depot-specific obesity treatment.

Bariatric surgery and bone disease: from clinical perspective to molecular insights

The use of bariatric surgery for the treatment of morbid obesity has increased annually for the last decade. Although many studies have demonstrated the efficacy and durability of bariatric surgery for weight loss, there are limited data regarding long-term side effects of these procedures. Recently, there has been an increased focus on the impact of bariatric surgery on bone metabolism. Bariatric surgery utilizes one or more of three mechanisms of action resulting in sustained weight loss. These include restriction (gastric banding, vertical banded gastroplasty and sleeve gastrectomy), malabsorption surgery with or without associated restriction (Roux en Y gastric bypass, duodenal switch, biliopancreatic diversion and jejunoileal bypass) and changes in gut-derived hormones that control energy metabolism also referred to as neuro-hormonal control of energy metabolism (Roux en Y gastric bypass, duodenal switch, biliopancreatic diversion, jejunoileal bypass, surgical procedures as above and gastric sleeve). Weight reduction has been associated with increased bone resorption but the mechanisms behind this have not yet been fully elucidated. Each of the mechanisms of action of bariatric surgery (restriction, malabsorption, neuro-hormonal control of energy metabolism) may uniquely affect bone resorption. In this paper we will review the current state of knowledge regarding the relationship between bariatric surgery and bone metabolism with emphasis on possible mechanisms of action such as malnutrition, hormonal interactions and mechanical unloading of the skeleton. Further, we suggest a future research agenda.

Peptide YY regulates bone remodeling in mice: a link between gut and skeletal biology

Background & Aims

Gastrointestinal peptides are increasingly being linked to processes controlling the maintenance of bone mass. Peptide YY (PYY), a gut-derived satiety peptide of the neuropeptide Y family, is upregulated in some states that also display low bone mass. Importantly, PYY has high affinity for Y-receptors, particularly Y1R and Y2R, which are known to regulate bone mass. Anorexic conditions and bariatric surgery for obesity influence circulating levels of PYY and have a negative impact on bone mass, but the precise mechanism behind this is unclear. We thus examined whether alterations in PYY expression affect bone mass.

Methods

Bone microstructure and cellular activity were analyzed in germline PYY knockout and conditional adult-onset PYY over-expressing mice at lumbar and femoral sites using histomorphometry and micro-computed tomography.

Results

PYY displayed a negative relationship with osteoblast activity. Male and female PYY knockout mice showed enhanced osteoblast activity, with greater cancellous bone mass. Conversely, PYY over-expression lowered osteoblast activity in vivo, via a direct Y1 receptor mediated mechanism involving MAPK stimulation evident in vitro. In contrast to PYY knockout mice, PYY over expression also altered bone resorption, as indicated by greater osteoclast surface, despite the lack of Y-receptor expression in osteoclastic cells. While evident in both sexes, cellular changes were generally more pronounced in females.

Conclusions

These data demonstrate that the gut peptide PYY is critical for the control of bone remodeling. This regulatory axis from the intestine to bone has the potential to contribute to the marked bone loss observed in situations of extreme weight loss and higher circulating PYY levels, such as anorexia and bariatric obesity surgery, and may be important in the maintenance of bone mass in the general population.

Examining the link between bariatric surgery, bone loss, and osteoporosis: a review of bone density studies

As the popularity of bariatric surgery to treat morbid obesity has risen, so has a concern of increased skeletal fragility secondary to accelerated bone loss following bariatric procedures. We reviewed cross-sectional and prospective literature reporting bone density outcomes following bariatric surgical treatment for morbid obesity. Prospective research provides evidence of hip and lumbar spine areal bone mineral density (aBMD) reductions primarily in women despite calcium and vitamin D supplementation. Femoral neck aBMD declines of 9-11% and lumbar spine aBMD reductions up to 8% were observed at the first post-operative year following malabsorptive procedures. Mean T- and Z-scores up to 25 years following surgery remained within normal and healthy ranges. Of those studies reporting development of osteoporosis following gastric bypass, one woman became osteoporotic after 1 year. Despite observed bone loss in the hip region post-surgery, data do not conclusively support increased incidence of osteoporosis or increased fracture risk in post-bariatric patients. However, given the limitations of dual energy X-ray absorptiometry technology in this population and the relative lack of long-term prospective studies that include control populations, further research is needed to provide conclusive evidence regarding fracture outcomes in this population.

Alveolar bone loss and periodontal status in a bariatric patient: a brief review and case report

To review the effects of obesity surgery on oral health and to present a case report of the periodontal condition of an obese woman who underwent bariatric surgery. A search of studies related to bariatric surgery and oral health was made in PubMed. For case report, BMI, salivary flow, and periodontal condition were evaluated during three different periods. The oral health problems found were dental wear, periodontal diseases, xerostomia, and dental caries. The patient who was evaluated before bariatric surgery and was followed up for 2 years, lost 40.4 kg, presented normal blood glucose levels and controlled hypertension without medication. Salivary flow remained of equal value in the first year, there was an increase in mean probing depth and there existed low bone density in these sites. Patients who have undergone bariatric surgery need to be closely monitored after surgery to prevent the development of oral complications, especially periodontal conditions.

[Follow-up after bariatric surgery]

BACKGROUND

The number of bariatric surgical procedures in Norway is increasing. Patients who undergo bariatric surgery may experience surgical, medical and nutritional complications. Follow-up of these patients is therefore important.

METHODS

The article is based on non-systematic literature searches in PubMed and on the clinical experience of the authors.

RESULTS

Bariatric surgery induces significant and sustained weight loss and improves obesity-related disorders. Gastric bypass is the most commonly performed bariatric procedure in Norway. This procedure is associated with a 30-day mortality of below 0.5 %, while severe complications occur in approximately 5 % of patients. Late complications include internal herniation, intestinal ulcers and gallbladder disease. After surgery all patients are given iron, vitamin D/calcium and vitamin B12 supplements to prevent vitamin and mineral deficiencies. Gastrointestinal symptoms and postprandial hypoglycaemia after surgery can be improved by dietary modifications, and the need for anti-diabetic and blood pressure lowering medications is reduced. Dose adjustment of other medications may also be necessary. Pregnancy is not recommended during the first year after bariatric surgery. Many patients need plastic surgery after the operation.

INTERPRETATION

Complications after bariatric surgery may manifest in the long term. Regular follow-up is required. General practitioners should be responsible for follow-up in the long term, and should be familiar with common and serious complications as well as normal symptomatology after bariatric surgery.

Ultrasonic value is not useful to detect bone changes following a biliopancreatic diversion

To study the evolution of the bone mass by ultrasonic transmission after biliopancreatic diversion. Forty eight morbid obese patients were prospectively studied during 36 months following the Larrad biliopancreatic diversion. The bone metabolism was studied by PTHi and the urinary pirydinolines. The bone mass by echography and bone densitometry, which correlate to the levels of PTHi and pyridinolines. After 3 years the bone mass decreased from 50.15 +/- 7.31 kg/m(2), preoperatively, to 34.03 +/- 4.53 kg/m2 (p < 0.001). There was an increase of the PTHi value (from 71.4 +/- 79.6 to 91.65 +/- 43.06 pg/ml) (p = 0.01), and the urinary pirydinolines (from 7.93 +/- 4.06 an 11.4 +/- 10.12 nM/mM) (p < 0.05). The ultrasonic transmission speed increased (from 1,990.93 +/- 62.38 to 2,035.25 +/- 53.98 m/s). However, the bone mineral content (BMC) did not show changes (from 3,016.5 +/- 562.8 to 2,909.6 +/- 304.2 g), as well as the Bone Mineral Density (BMD) (of 1,174.2 +/- 98.8 g/cm2). Neither correlation was found between the BMD (r = 0.212; p = 0.6), the BMC (r =-0.125; p = 0.768), and the T-score (r = 0.592, p = 0.093). The study of the bone mass through ultrasonic transmission speed revealed low sensitivity during the assessment of the morbid obese patients. A percentage of cases of osteopenia were observed despite the fact that they are not reflected in the bone content or in the bone mass. Ultrasonic evaluation of bone mass has no value in the morbidly obese, by the clear negative correlation between ultrasound velocity and thickness of soft tissue.

Moderate weight gain does not influence bone metabolism in skeletally mature female rats

Bone mass is correlated with body weight during growth. However, it is unclear how bone mass is influenced by weight gain following skeletal maturity. The purpose of this study was to determine the effects of weight maintenance and two rates of weight gain on bone metabolism using skeletally mature female rats. Eight-month-old female rats were fed one of 3 diets for 13 weeks: Lieber-DeCarli liquid diet ad lib (control diet), the same diet with caloric restriction to maintain initial body weight (calorie-restricted diet), and the same diet fed ad lib with the exception that appetite was enhanced (calorie-increased diet) by replacing a small quantity of maltose-dextran isocalorically with ethanol (0.5% caloric intake). Compared to baseline, rats fed the calorie-restricted, control, and calorie-increased diets changed in weight by -1+/-2% (mean+/-SE), 10+/-3%, and 21+/-2%, respectively. Weight gain was associated with a significant increase in serum leptin, a putative regulator of bone formation. In contrast, significant differences in tibial bone mineral content and density were not detected among treatments groups following dietary intervention or between treatment groups and the baseline group. Similarly, indices of cancellous bone architecture (area, trabecular number, thickness, and separation) and bone turnover (mineralizing perimeter, mineral apposition rate, and bone formation rate) did not differ among groups following dietary intervention. Our findings suggest that neither weight gain nor increased serum leptin levels, over the range evaluated, influence bone metabolism in skeletally mature female rats.

[Abnormalities of bone metabolism in bariatric surgery]

Obesity is an ever-increasing disease in our environment, and a major risk factor for the development of other chronic diseases that increase morbidity and mortality. Bariatric surgery is an effective treatment for obesity, since it not only allows a significant and sustained loss of weight, but also an important reduction of its co-morbidities. However, this treatment is not free of complications, since along with weight loss, frequent nutritional and metabolic deficiencies have been described. These complications are particularly frequent when mixed surgical procedures with a restrictive and malabsortive component such as Roux-en-Y gastric bypass and biliopancreatic diversion are performed. The nutritional deficiencies observed include, to a greater or lesser extent, malabsorption of fat and liposoluble vitamins, as well as other micronutrients such as calcium. As a result, disorders of bone mineral metabolism with skeletal manifestations that include bone mass reduction, increased bone turnover and defective bone mineralization may develop.

Contraceptive use among women with a history of bariatric surgery: a systematic review

BACKGROUND

Weight loss after bariatric surgery often improves fertility but can pose substantial risks to maternal and fetal outcomes. Women who have undergone a bariatric surgical procedure are currently advised to delay conception for up to 2 years.

STUDY DESIGN

We conducted a systematic review of the literature, from database (PubMed) inception through February 2009, to evaluate evidence on the safety and effectiveness of contraceptive use among women with a history of bariatric surgery.

RESULTS

From 29 articles, five met review inclusion criteria. One prospective, noncomparative study reported 2 pregnancies among 9 (22%) oral contraceptive (OC) users following biliopancreatic diversion, and one descriptive study reported no pregnancies among an unidentified number of women taking OCs following laparoscopic adjustable gastric banding. Of two pharmacokinetic studies, one found lower plasma levels of norethisterone and levonorgestrel among women having had a jejunoileal bypass, as compared to nonoperated, normal-weight controls. The other study found no difference in plasma levels of D-norgestrel between women having a jejunoileal bypass of either 1:3 or 3:1 ratio between the length of jejunum and ileum left in continuity, but women with a 1:3 ratio had significantly higher plasma levels of D-norgestrel than extremely obese controls not operated upon.

CONCLUSIONS

Evidence regarding OC effectiveness following a bariatric surgical procedure is quite limited, although no substantial decrease in effectiveness was identified from available studies. Evidence on failure rates for other contraceptive methods and evidence on safety for all contraceptive methods was not identified.

Increase of bone resorption and the parathyroid hormone in postmenopausal women in the long-term after Roux-en-Y gastric bypass

BACKGROUND

The effects of Roux-en-Y Gastric Bypass (RYGB) on bone in the long-term remains unclear. We assessed bone metabolism and bone mineral density (BMD) 1 to 5 years after RYGB.

METHODS

We designed a retrospective cohort study in 26 postmenopausal women (58.0+/-3.9 years old) with RYGB 3.5+/-1.1 years before (body mass index (BMI) 29.5+/-3.8 kg/m2, presurgery 43.6+/-5.5 kg/m2) and 26 nonoperated women (57.5+/-4.7 years old, BMI 29.2+/-4.1 kg/m2) matched by age and BMI. The main measures were BMD, serum carboxy telopeptide (CTx), total alkaline phosphatases (ALP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), and ghrelin.

RESULTS

RYGB group, compared to nonoperated women, had higher CTx (0.71+/-0.21 vs. 0.43+/-0.15 ng/ml; P<0.01) and PTH (68.3+/-35 vs. 49.4+/-16 pg/ml; P=0.02). There were no differences between RYGB and nonoperated women in: calcium and vitamin D intake (759+/-457 vs. 705+/-460 mg/day; 176+/-160 vs. 111+/-86 UI/day), ghrelin (763+/-336 vs. 621+/-274 pg/ml), ALP (101+/-22 vs. 94+/-25 UI/l), 25OHD (18.8+/-7.6 vs. 17.4 +/- 5.9 ng/ml), lumbar spine BMD (1.059+/-0.32 vs. 1.071+/-0.207 g/cm2), or femoral neck BMD (0.892+/-0.109 vs. 0.934+/-1.1 g/cm2).

CONCLUSIONS

RYGB is associated to high bone resorption and hyperparathyroidism prevalence in postmenopausal women in the long-term. This occurs independently of the intake of calcium, vitamin D status, or ghrelin and does not seem to affect BMD after RYGB.

Elevated expression of osteopontin may be related to adipose tissue macrophage accumulation and liver steatosis in morbid obesity

OBJECTIVE

Osteopontin (OPN) plays an important role in the development of insulin resistance and liver complications in dietary murine models. We aimed to determine the expression pattern of OPN and its receptor CD44 in obese patients and mice according to insulin resistance and liver steatosis.

RESEARCH DESIGN AND METHODS

OPN and CD44 expressions were studied in 52 morbidly obese patients and in mice. Cellular studies were performed in HepG2 cells.

RESULTS

Hepatic OPN and CD44 expressions were strongly correlated with liver steatosis and insulin resistance in obese patients and mice. This increased OPN expression could be due to the accumulation of triglycerides, since fat loading in HepG2 promotes OPN expression. In contrast, OPN expression in adipose tissue (AT) was enhanced independently of insulin resistance and hepatic steatosis in obese patients. The elevated OPN expression in AT was paralleled with the AT macrophage infiltration, and both phenomena were reversed after weight loss. The circulating OPN level was slightly elevated in obese patients and was not related to liver steatosis. Further, AT did not appear to secrete OPN. In contrast, bariatric surgery-induced weight loss induced a strong increase in circulating OPN.

CONCLUSIONS

The modestly elevated circulating OPN levels in morbidly obese patients were not related to liver steatosis and did not appear to result from adipose tissue secretion. In subcutaneous AT, expression of OPN was directly related to macrophage accumulation independently from liver complications. In contrast, hepatic OPN and CD44 expressions were related to insulin resistance and steatosis, suggesting their local implication in the progression of liver injury.

Changes in bone mineral density, body composition and adiponectin levels in morbidly obese patients after bariatric surgery

BACKGROUND

Gastric bypass surgery (GBP) is increasingly used as a treatment option in morbid obesity. Little is known about the effects of this surgery on bone mineral density (BMD) and the underlying mechanisms. To evaluate changes on BMD after GBP and its relation with changes in body composition and serum adiponectin, a longitudinal study in morbid obese subjects was conducted.

METHODS

Forty-two women (BMI 45.0 +/- 4.3 kg/m(2); 37.7 +/- 9.6 years) were studied before surgery and 6 and 12 months after GBP. Percentage of body fat (%BF), fat-free mass (FFM), and BMD were measured by dual-energy X-ray absorptiometry and serum adiponectin levels by RIA.

RESULTS

Twelve months after, GBP weight was decreased by 34.4 +/- 6.5% and excess weight loss was 68.2 +/- 12.8%. Significant reduction (p < 0.001) in total BMD (-3.0 +/- 2.1%), spine BMD (-7.4 +/- 6.8%) and hip BMD (-10.5 +/- 5.6%) were observed. Adiponectin concentration increased from 11.4 +/- 0.7 mg/L before surgery to 15.7 +/- 0.7 and 19.8 +/- 1.0 at the sixth and twelfth month after GBP, respectively (p < 0.001). Thirty-seven percent of the variation in total BMD could be explained by baseline weight, initial BMD, BF reduction, and adiponectin at the twelfth month (r (2) = 0.373; p < 0.001). Adiponectin at the twelfth month had a significant and positive correlation with the reduction of BMD, unrelated to baseline and variation in body composition parameters (adjusted correlation coefficient: r = 0.36).

CONCLUSION

GBP induces a significant BMD loss related with changes in body composition, although some metabolic mediators, such as adiponectin increase, may have an independent action on BMD which deserves further study.

The bone-adipose axis in obesity and weight loss

Body fat and lean mass are correlated with bone mineral density, with obesity apparently exerting protection against osteoporosis. The pathophysiological relevance of adipose tissue in bone integrity resides in the participation of adipokines in bone remodeling through effects on deposition and resorption. On the other hand, the skeleton has recently emerged as an endocrine organ with effects on body weight control and glucose homeostasis through the actions of bone-derived factors such as osteocalcin and osteopontin. The cross-talk between adipose tissue and the skeleton constitutes a homeostatic feedback system with adipokines and molecules secreted by osteoblasts and osteoclasts representing the links of an active bone-adipose axis. Given the impact of bariatric surgery on absorption and the adipokine secretory pattern, to focus on the changes taking place following surgical-induced weight loss on this dynamic system merits detailed consideration.

Hyperparathyroidism and Vitamin D Deficiency after Laparoscopic Gastric Bypass

Hyperparathyroidism (HPT) can occur after gastric bypass because of the alteration in vitamin D and calcium absorption. Adequate serum vitamin D concentrations have not been clearly defined in this patient population. Vitamin D (Vit D) and parathyroid hormone (PTH) were assessed 1 year after laparoscopic gastric bypass (LGB). The prevalence of HPT and Vit D deficiency were determined and their association was evaluated using Fisher's exact test. Ninety-three patients (aged 44 ± 1.1 years, 49.6 ± 0.67 kg/m2 body mass index, 79.6% female, 69.6% white) were evaluated. The prevalence of Vit D deficiency (less than 20 ng/mL) and HPT (greater than 65 pg/mL) was 23.6 per cent (n = 22) and 25.7 per cent (n = 28), respectively. Among patients with HPT, only eight of 28 (28.6%) had Vit D deficiency, and of those with Vit D deficiency, only eight of 22 (36.4%) had HPT. There was a weak inverse correlation (r = –0.37) between PTH and Vit D. Blacks are at higher risk for Vit D deficiency. There was no significant association between Vit D deficiency and HPT, Vit D deficiency and Roux limb length, or HPT and Roux limb length. After LGB, Vit D deficiency and hyperparathyroidism occur commonly. Body mass index and Roux limb length are not associated with these two conditions, but racial differences do exist. There is a weak inverse correlation between Vit D and PTH. Further research is needed to elucidate the causes, treatments, and significance of HPT after LGB.