Bariatric surgery and bone disease: from clinical perspective to molecular insights. Int J Obes (Lond). 2012;36:1373-1379. [PMID: 22828943 DOI: 10.1038/ijo.2012.115]

Short-term effects of Roux-en-Y gastric bypass or gastric sleeve on bone mineral density and calciotropic hormones: a systematic review and meta-analysis

Roux-en-Y gastric bypass (RYGB) and gastric sleeve (GS) have been associated with significant reductions in bone mineral density (BMD) and fluctuations in serum levels of calciotropic hormones. These changes pose a risk to bone health. The study assessed the short-term (12 and 24 months) effects of RYGB and GS on BMD and calciotropic hormones. PubMed, Embase, and Cochrane Library databases were searched. Analyses considered follow-up (12 and 24 months) with BMD as main outcome at three sites (femoral neck, total hip, and lumbar spine) and one for each calciotropic hormone (25 OH vitamin D and parathyroid hormone [PTH]). Estimated effect sizes were calculated as standardized mean differences (SMD), confidence interval of 95%, and P value. Nine studies totaling 473 participants (RYGB = 261 and GS = 212) were included. RYGB resulted in lower BMD than GS at 12 months for femoral neck (SMD = -0.485, 95% CI [-0.768, -0.202], P = .001), lumbar spine (SMD = -0.471, 95% CI [-0.851, -0.092], P = .015), and total hip (SMD = -0.616, 95% CI [-0.972, -0.259], P = .001), and at 24 months for total hip (SMD = -0.572, 95% CI [-0.907, -0.238], P = .001). At 24 months, 25 OH vitamin D was lower in RYGB than GS (SMD = -0.958 [-1.670, -0.245], P = .008) and PTH levels were higher in RYGB than in GS (SMD = 0.968 [0.132, 1.804, P = .023]). RYGB demonstrated significant reduction in regional BMD. It also induces lower serum 25 OH vitamin D and higher PTH levels than GS. The results support the need for preventive bone health measures in the short-term postoperative period, especially in the case of RYGB.

Ghrelin enhances tubular magnesium absorption in the kidney

Osteoporosis after bariatric surgery is an increasing health concern as the rate of bariatric surgery has risen. In animal studies mimicking bariatric procedures, bone disease, together with decreased serum levels of Ca2+, Mg2+ and the gastric hormone Ghrelin were described. Ghrelin regulates metabolism by binding to and activating the growth hormone secretagogue receptor (GHSR) which is also expressed in the kidney. As calcium and magnesium are key components of bone, we tested the hypothesis that Ghrelin-deficiency contributes to osteoporosis via reduced upregulation of the renal calcium channel TRPV5 and the heteromeric magnesium channel TRPM6/7. We expressed GHSR with TRPV5 or TRPM6/7 channel in HEK293 cells and treated them with purified Ghrelin. Whole-cell current density was analyzed by patch-clamp recording. Nephron-specific gene expression was performed by tubular microdissection followed by qPCR in wild-type (WT) mice, and immunofluorescent imaging of GHSR-eGFP mice. Tubular magnesium homeostasis was analyzed in GHSR-null and WT mice at baseline and after caloric restriction. After Ghrelin exposure, whole-cell current density did not change for TRPV5 but increased for TRPM6/7 in a dose-dependent fashion. Applying the Ghrelin-mimetic (D-Trp7, Ala8,D-Phe10)-α-MSH (6-11) amide without and with the GHSR antagonist (D-Lys3)-GHRP6, we confirmed the stimulatory role of Ghrelin towards TRPM6/7. As GHSR initiates downstream signaling via protein kinase A (PKA), we found that the PKA inhibitor H89 abrogated TRPM6/7 stimulation by Ghrelin. Similarly, transfected Gαs, but not the Gαs mutant Q227L, nor Gαi2, Gαq, or Gα13 upregulated TRPM6/7 current density. In microdissected TALs and DCTs similar levels of GHSR mRNA were detected. In contrast, TRPM6 mRNA was expressed in the DCT and also detected in the TAL at 25% expression compared to DCT. Immunofluorescent studies using reporter GHSR-eGFP mice showed a strong eGFP signal in the TAL but surprisingly displayed no eGFP signal in the DCT. In 3-, 6-, and 9-month-old GHSR-null and WT mice, baseline serum magnesium was not significantly different, but 24-h urinary magnesium excretion was elevated in 9-month-old GHSR-null mice. In calorically restricted GHSR-null mice, we detected excess urinary magnesium excretion and reduced serum magnesium levels compared to WT mice. The kidneys from calorically restricted WT mice showed upregulated gene expression of magnesiotropic genes Hnf1b, Cldn-16, Cldn-19, Fxyd-2b, and Parvalbumin compared to GHSR-null mice. Our in vitro studies show that Ghrelin stimulates TRPM6/7 via GHSR and Gαs-PKA signaling. The murine studies are consistent with Ghrelin-GHSR signaling inducing reduced urinary magnesium excretion, particularly in calorically restricted mice when Ghrelin levels are elevated. This effect may be mediated by Ghrelin-upregulation of TRPM6 in the TAL and/or upregulation of other magnesiotropic genes. We postulate that rising Ghrelin levels with hunger contribute to increased renal Mg2+ reabsorption to compensate for lack of enteral Mg2+ uptake.

Improved femoral micro-architecture in adult male individuals with overweight: fracture resistance due to regional specificities

BACKGROUND

It is still unclear whether femoral fracture risk is positively or negatively altered in individuals with overweight. Considering the lack of studies including men with overweight, this study aimed to analyze regional specificities in mechano-structural femoral properties (femoral neck and intertrochanteric region) in adult male cadavers with overweight compared to their normal-weight age-matched counterparts.

METHODS

Ex-vivo osteodensitometry, micro-computed tomography, and Vickers micro-indentation testing were performed on femoral samples taken from 30 adult male cadavers, divided into the group with overweight (BMI between 25 and 30 kg/m2; n = 14; age:55 ± 16 years) and control group (BMI between 18.5 and 25 kg/m2; n = 16; age:51 ± 18 years).

RESULTS

Better quality of trabecular and cortical microstructure in the inferomedial (higher trabecular bone volume fraction, trabecular thickness, and cortical thickness, coupled with reduced cortical pore diameter, p < 0.05) and superolateral femoral neck (higher trabecular number and tendency to lower cortical porosity, p = 0.043, p = 0.053, respectively) was noted in men with overweight compared to controls. Additionally, the intertrochanteric region of men with overweight had more numerous and denser trabeculae, coupled with a thicker and less porous cortex (p < 0.05). Still, substantial overweight-induced change in femoral osteodensitometry parameters and Vickers micro-hardness was not demonstrated in assessed femoral subregions (p > 0.05).

CONCLUSIONS

Despite the absence of significant changes in femoral osteodensitometry, individuals with overweight had better trabecular and cortical femoral micro-architecture implying higher femoral fracture resistance. However, the microhardness was not significantly favorable in the individuals who were overweight, indicating the necessity for further research.

Mechanisms of action of incretin receptor based dual- and tri-agonists in pancreatic islets

Simultaneous activation of the incretin G-protein-coupled receptors (GPCRs) via unimolecular dual-receptor agonists (UDRA) has emerged as a new therapeutic approach for type 2 diabetes. Recent studies also advocate triple agonism with molecules also capable of binding the glucagon receptor. In this scoping review, we discuss the cellular mechanisms of action (MOA) underlying the actions of these novel and therapeutically important classes of peptide receptor agonists. Clinical efficacy studies of several UDRAs have demonstrated favorable results both as monotherapies and when combined with approved hypoglycemics. Although the additive insulinotropic effects of dual glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) agonism were anticipated based on the known actions of either glucagon-like peptide-1 (GLP-1) or glucose-dependent insulinotropic peptide (GIP) alone, the additional benefits from GCGR were largely unexpected. Whether additional synergistic or antagonistic interactions among these G-protein receptor signaling pathways arise from simultaneous stimulation is not known. The signaling pathways affected by dual- and tri-agonism require more trenchant investigation before a comprehensive understanding of the cellular MOA. This knowledge will be essential for understanding the chronic efficacy and safety of these treatments.

Biomechanical CT to Assess Bone After Sleeve Gastrectomy in Adolescents With Obesity: A Prospective Longitudinal Study

Sleeve gastrectomy (SG) is effective in treating cardiometabolic complications of obesity but is associated with bone loss. Our aim was to determine the effect of SG on the lumbar spine by biomechanical CT analysis in adolescents/young adults with obesity. We hypothesized that SG would lead to a decrease in strength and bone mineral density (BMD) compared with nonsurgical controls. In a 12-month prospective nonrandomized study, adolescents/young adults with obesity underwent SG (n = 29, 18.0 ± 2.1 years, 23 female) or were followed without surgery (controls, n = 30, 17.95 ± 3.0 years, 22 female). At baseline and 12 months, participants underwent quantitative computed tomography (QCT) of L1 and L2 for biomechanical assessment and MRI of the abdomen and mid-thigh for body composition assessment. Twelve-month changes between groups and within groups were assessed. Analyses were controlled for baseline and 12-month changes in body mass index (BMI) by multivariable analyses. Regression analysis was performed to evaluate the effect of body composition on bone parameters. Our institutional review board (IRB) approved the study, and informed consent/assent was obtained. Participants in the SG group had a higher baseline BMI than controls (p = 0.01) and lost an average of 34.3 ± 13.6 kg 12 months after surgery, whereas weight was unchanged in controls (p < 0.001). There were significant reductions in abdominal adipose tissue and thigh muscle area in the SG group compared with controls (p < 0.001). Bone strength, bending stiffness, and average and trabecular volumetric BMD decreased in the SG group compared with controls (p < 0.001). After controlling for change in BMI, a 12-month reduction in cortical BMD was significant in the SG group compared with controls (p = 0.02). Reductions in strength and trabecular BMD were associated with reductions in BMI, visceral adipose tissue, and muscle (p ≤ 0.03). In conclusion, SG in adolescents decreased strength and volumetric BMD of the lumbar spine compared with nonsurgical controls. These changes were associated with decreases in visceral fat and muscle mass. © 2023 American Society for Bone and Mineral Research (ASBMR).

Intestinal Calcium Absorption Decreases After Laparoscopic Sleeve Gastrectomy Despite Optimization of Vitamin D Status

CONTEXT

Laparoscopic sleeve gastrectomy (LSG), now the most commonly performed bariatric operation, is a highly effective treatment for obesity. While Roux-en-Y gastric bypass is known to impair intestinal fractional calcium absorption (FCA) and negatively affect bone metabolism, LSG's effects on calcium homeostasis and bone health have not been well characterized.

OBJECTIVE

We determined the effect of LSG on FCA, while maintaining robust 25-hydroxyvitamin D (25OHD) levels and recommended calcium intake.

DESIGN, SETTING, PARTICIPANTS

Prospective pre-post observational cohort study of 35 women and men with severe obesity undergoing LSG.

MAIN OUTCOMES

FCA was measured preoperatively and 6 months postoperatively with a gold-standard dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and bone mineral density (BMD) by dual-energy X-ray absorptiometry and quantitative computed tomography.

RESULTS

Mean ± SD FCA decreased from 31.4 ± 15.4% preoperatively to 16.1 ± 12.3% postoperatively (P < 0.01), while median (interquartile range) 25OHD levels were 39 (32-46) ng/mL and 36 (30-46) ng/mL, respectively. Concurrently, median 1,25-dihydroxyvitamin D level increased from 60 (50-82) pg/mL to 86 (72-107) pg/mL (P < 0.01), without significant changes in parathyroid hormone or 24-hour urinary calcium levels. Bone turnover marker levels increased substantially, and areal BMD decreased at the proximal femur. Those with lower postoperative FCA had greater areal BMD loss at the total hip (ρ = 0.45, P < 0.01).

CONCLUSIONS

FCA decreases after LSG, with a concurrent rise in bone turnover marker levels and decline in BMD, despite robust 25OHD levels and with recommended calcium intake. Decline in FCA could contribute to negative skeletal effects following LSG.

Risk of fracture following gastric surgery for benign and malignant conditions: A study level pooled analysis of population-based cohort studies

BACKGROUND

Metabolic changes may occur following gastric surgery, which has been reported to contribute to bone loss, osteoporosis and even bone fracture. However, the evidence regarding the relationship between gastric surgery for benign and malignant conditions and risk of fracture is controversial. This study was conducted with the aim to evaluate whether gastric surgery is associated with a high risk of fracture.

METHODS

Major electronic databases were searched from inception through October 2021 for population-based cohort studies investigating the associations between gastric surgery (including bariatric gastric surgeries and surgeries for gastric benign and malignant gastric tumors) and risk of fracture compared with controls. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were derived using the random-effects Mantel-Haenszel model. Multiple subgroup analyses and sensitivity analyses were carried out to test sources of heterogeneity stratified by various study characteristics and the robustness of the results.

RESULTS

A total of 14 studies comprising 693134 individuals were identified for analysis. The RR for the risk of fracture in people undergoing gastric surgery was 1.45 [95% confidence interval (CI) 1.23 - 1.72; I^{2 =} 95.8%; P < 0.001] compared with that in control populations, among which the fracture sites of upper limb, spine, lower limb, pelvis and hip showed consistent significant results (all P < 0.05), whereas nonsignificant associations was noted for other fracture sites. Significant associations were also observed for patients having total or subtotal gastrectomy (RR 2.22, 95% CI 1.66 to 3.00), gastric bypass (RR 1.48, 95% CI 1.26 to 1.74), and a similar trend was observed for preserved passage procedures (including sleeve gastrectomy, gastric banding, vertical banded gastroplasty and other procedures that preserved the passage through the duodenum and proximal small bowel, in contrast to gastric bypass), though the difference did not reach statistically significant (RR 1.10, 95% CI 0.95 to 1.26). An evident increased risk in the age range from 40-59 years was observed (40-49 years: RR 1.36, 95% CI 1.19-1.55; 50-59 years: RR 2.48, 95% CI 1.58-3.90).

CONCLUSION

From this large pooled analysis of population-based cohort studies, evidence supports that fracture risk is increased in gastric surgery survivors compared with the control population. Early prevention and effective intervention strategies of bone fracture should be taken from clinicians and health policy makers.

CLINICAL TRIAL REGISTRATION

PROSPERO (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=291394), identifier CRD42021291394.

Changes in Sex Steroids and Enteric Peptides After Sleeve Gastrectomy in Youth in Relation to Changes in Bone Parameters

CONTEXT

Sleeve gastrectomy (SG) improves metabolic endpoints but is associated with impaired bone outcomes.

OBJECTIVE

To determine mechanisms contributing to impaired bone health in youth following SG.

METHODS

12-month longitudinal observational study in a multidisciplinary tertiary-care hospital, including 64 youth 13-25 years old with moderate-to-severe obesity (51 females); 30 underwent SG and 34 were nonsurgical (NS) controls. SG was undertaken after a combined decision-making process between treatment team and patient. The main outcome measures were fasting blood for enteric peptides, sex steroids, sclerostin, and bone turnover markers (N-terminal propeptide of type 1 procollagen [P1NP] and C-terminal cross-linking telopeptide [CTX]); dual-energy X-ray absorptiometry measures of areal bone mineral density (aBMD) and body composition; high resolution peripheral quantitative computed tomography; measures of volumetric BMD (vBMD); microfinite element analysis of strength estimates (distal radius and tibia).

RESULTS

SG had greater reductions in body mass index (BMI) z-scores, serum estrone, and the free androgen index (FAI) (P ≤ .046), and greater increases in sclerostin, P1NP, and CTX (P ≤ .010) than NS controls. Fasting ghrelin decreased in SG vs NS (P < .0001); fasting peptide YY did not change. Most changes were driven by female SG participants. Among females (the majority of study participants), after controlling for baseline age and race, reductions in total hip aBMD Z-scores were positively associated with changes in BMI, lean mass, estrone, FAI, and ghrelin, and inversely with changes in sclerostin.. Decreases in total vBMD of the radius and tibia were associated positively with decreases in BMI. Increases in CTX were associated with decreases in BMI, lean mass, and ghrelin, and increases in sclerostin.

CONCLUSION

Bone loss after SG in youth is associated with changes in body composition, sex steroids, sclerostin, and enteric peptides. These are potential targets for future preventative or therapeutic strategies.

The Impact of Bariatric Surgery on Bone Health: State of the Art and New Recognized Links

Bariatric surgery (BS) is the most effective therapy for severe obesity, which improves several comorbidities (such as diabetes, hypertension, dyslipidemia, among others) and results in marked weight loss. Despite these consensual beneficial effects, sleeve gastrectomy and Roux-en-Y gastric bypass (the two main bariatric techniques) have also been associated with changes in bone metabolism and progressive bone loss. The objective of this literature review is to examine the impact of bariatric surgery on bone and its main metabolic links, and to analyze the latest findings regarding the risk of fracture among patients submitted to bariatric surgery.

Bone Response to Weight Loss Following Bariatric Surgery

Obesity is a global health challenge that warrants effective treatments to avoid its multiple comorbidities. Bariatric surgery, a cornerstone treatment to control bodyweight excess and relieve the health-related burdens of obesity, can promote accelerated bone loss and affect skeletal strength, particularly after malabsorptive and mixed surgical procedures, and probably after restrictive surgeries. The increase in bone resorption markers occurs early and persist for up to 12 months or longer after bariatric surgery, while bone formation markers increase but to a lesser extent, suggesting a potential uncoupling process between resorption and formation. The skeletal response to bariatric surgery, as investigated by dual-energy X-ray absorptiometry (DXA), has shown significant loss in bone mineral density (BMD) at the hip with less consistent results for the lumbar spine. Supporting DXA studies, analyses by high-resolution peripheral quantitative computed tomography (HR-pQCT) showed lower cortical density and thickness, higher cortical porosity, and lower trabecular density and number for up to 5 years after bariatric surgery. These alterations translate into an increased risk of fall injury, which contributes to increase the fracture risk in patients who have been subjected to bariatric surgery procedures. As bone deterioration continues for years following bariatric surgery, the fracture risk does not seem to be dependent on acute weight loss but, rather, is a chronic condition with an increasing impact over time. Among the post-bariatric surgery mechanisms that have been claimed to act globally on bone health, there is evidence that micro- and macro-nutrient malabsorptive factors, mechanical unloading and changes in molecules partaking in the crosstalk between adipose tissue, bone and muscle may play a determining role. Given these circumstances, it is conceivable that bone health should be adequately investigated in candidates to bariatric surgery through bone-specific work-up and dedicated postsurgical follow-up. Specific protocols of nutrients supplementation, motor activity, structured rehabilitative programs and, when needed, targeted therapeutic strategies should be deemed as an integral part of post-bariatric surgery clinical support.

Understanding the Experience of Osteoporosis Risk in Bariatric Surgical Patients

Despite what is known about risk factors, preventive treatment, and increased prevalence of fragility fractures in post-bariatric surgical patients, little is known about how patient perspectives of osteoporosis risk inform their commitment to bone health. The purpose of this study was to examine the lived experience of osteoporosis risk in people who have had bariatric surgery. Interpretive phenomenology was used to explore osteoporosis from the perspectives of patients who have had bariatric surgery. Eligibility criteria included female, age older than 18 years, and able to understand and speak English. This research provided an understanding of the risk of osteoporosis from the constructed realities and experiences of those who have had bariatric surgery. Participants in this study incorrectly felt they had little to no risk for osteoporosis after bariatric surgery. Patients need to be aware of an increased risk for osteoporosis leading to the potential for fragility fractures after bariatric surgery; nurses are well positioned to enhance osteoporosis prevention efforts in this population through pre- and postoperative education.

Adequate vitamin D supplementation does not ameliorate bone loss following long limb-biliopancreatic diversion in morbidly obese women

OBJECTIVES

The objective of this study is to investigate the effect of adequate vitamin D supplementation on bone mineral density (BMD) following long limb-biliopancreatic diversion (LL-BPD), a malabsorptive bariatric operation.

BACKGROUND

Marked weight loss following bariatric surgery is associated with significant decrease in BMD, attributed to the weight loss and to nutritional, mineral, and vitamin D deficiencies resulting in secondary hyperparathyroidism.

METHODS

Two groups, of 35 and 37 healthy, obese (BMI, 50.4 + 6.6 and 46.5 + 4.8 g/cm²), premenopausal, normally menstruating women underwent LL-BPD. Both groups received high-calcium diets, 600 IU of vitamin D, and 1000 mg elemental calcium daily, while group B received an extra dose of vitamin D (10,000 IU/day) during the first postoperative month, followed by dose adjustment in order to maintain 25OHD concentration higher than 30 μg/L. Areal BMD (aBMD) was measured at the lumbar spine preoperatively and 1 year postoperatively.

RESULTS

One year postoperatively, BMI decreased by approximately 19 kg/m² in both groups, while 25-OH-vitamin D levels did not change in group A (18.7 + 9.1 to 20.2 + 13.0 μg/L, (p = 0.57)) and increased in group B (15.58 ± 5.73 to 52.97 ± 15.46 μg/L, (p = < 0.001). PTH levels increased in group A (from 38.5 ± 12.2 to 51.2 ± 32.8 pg/ml) (p = 0.047) and decreased in group B (from 51.61 ± 18.7 to 45.1 ± 17.8 pg/ml) (p = 0.042). Lumbar spine aBMD decreased similarly in both groups (p = 0.311, for the comparison between groups) from 1.198 + 0.14 to 1.103 + 0.15 g/cm² in group A (p < 0.001) and from 1.157 + 0.14 to 1.076 + 0.14 g/cm² in group B (p < 0.001) and Z-score from 0.93 + 0.97 to 0.19 + 1.02, (p < 0.001) and from 1.15 + 1.29 to 0.419 + 1.28, (p < 0.001), respectively.

CONCLUSIONS

LL-BPD leads to similar and significant bone mass reduction 1 year postoperatively, irrespective of adequate vitamin D replacement and in the absence of secondary hyperparathyroidism.

Adherence to Nutritional Supplementation Determines Postoperative Vitamin D Status, but Not Levels of Bone Resorption Marker, in Sleeve-Gastrectomy Patients

BACKGROUND

Taking advantage of isomeric form of vitamin E in the supplement, adherence to supplement could be evaluated by changes in circulating α- and γ-tocopherol concentrations. Accordingly, effects of supplementation on postoperative nutrition and bone metabolism were studied in terms of adherence.

METHODS

Thirty-eight SG patients were all prescribed a postoperative nutritional supplement containing a low dose of vitamin D (600 IU) and calcium (200 mg). Blood samples were collected prior to (M0) and 6 months after (M6) surgery and concentrations of nutrients and C-terminal telopeptide of type I collage (CTX), a marker of bone resorption, were measured. Adherence and non-adherence were stratified according to change (△, M6-M0) in serum α-tocopherol concentrations (> 0 vs. ≤ 0, respectively).

RESULTS

When M0 and M6 were compared, there were significant increases in serum concentrations of 25(OH)D, α-tocopherol and selenium, whereas there were reductions in parathyroid hormone, ferritin, and γ-tocopherol. At M6, the prevalence of vitamin D insufficiency (25(OH)D < 30 ng/mL) and high CTX were 72 and 26%, respectively. When comparison was made between adherence and non-adherence, only △25(OH)D concentrations, but no other nutrients nor postoperative CTX differed. Multiple linear regression demonstrated that postoperative vitamin D status was independently associated with its preoperative concentrations (β = 0.85, p < 0.001) and adherence (β = 0.52, p < 0.05).

CONCLUSION

SG patients' adherence to supplementation, even with a low dose of vitamin D and calcium, determined vitamin D status but not bone resorption marker concentrations, at least within 6 months after surgery.

Short-Term Changes on Body Composition and Bone Mass After One-Anastomosis Gastric Bypass: a Prospective Observational Study

PURPOSE

Bariatric surgery generates a large weight loss. It is considered a successful surgery when 50% of the excess weight loss is reached. However, this measure does not include some variables that may have a direct impact on a patient's health, such as fat-free mass (FFM) or bone mass. Therefore, the aim of this study is to evaluate body composition and bone mass in patients undergoing one-anastomosis gastric bypass (OAGB).

METHODS

A prospective observational study was performed in patients undergoing OAGB. Body composition and bone mass were evaluated by bioelectrical impedance analysis at baseline (1 day prior to surgery), at 6 and 12 months after surgery.

RESULTS

A total of 94 patients (67% females and 33% males) were included in the study. The excess BMI loss at 6 and 12 months after surgery was 97.9 ± 20.1% and 110.2 ± 30.5% respectively. The FFM showed a reduction of 6.6 ± 4.8 kg (p < 0.01) 6 months after surgery and of 7.9 ± 4.9 kg (p < 0.01) at 12 months, meaning a decrease of 10.5 ± 7.3% and a 12.9 ± 6.6% respectively. The bone mass decrease was 10.1 ± 6.9% (p < 0.01) and 12.9 ± 6.5% (p < 0.01) at 12 months after OAGB.

CONCLUSIONS

OAGB obtains a relevant weight loss in patients with morbid obesity, mainly, due to fat mass reductions. However, this procedure also provokes FFM and bone mass decreases, especially in females, but not significantly greater than other restrictive or mixed procedures.

Long-Term Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on Bone Mineral Density: a 4-Year Longitudinal Study

INTRODUCTION

Bone mineral density (BMD) declines in the initial years after bariatric surgery, but long-term skeletal effects are unclear and comparisons between sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are rare.

DESIGN AND METHODS

An observational longitudinal study of obese patients undergoing SG or RYGB was performed. Whole-body (WB) BMD, along with BMD of the total hip (TH), femoral neck (FN), and lumbar spine (LS), was measured by dual-energy X-ray absorptiometry (DXA) before surgery and yearly thereafter for 4 years. Calciotropic hormones were also measured.

RESULTS

Forty-seven patients undergoing RYGB surgery and 28 patients undergoing SG were included. Four years after RYGB, BMD declined by 2.8 ± 5.8% in LS, 8.6 ± 5% in FN, 10.9 ± 6.3% in TH, and 4.2 ± 6.2% in WB, relative to baseline. For SG, BMD declined by 8.1 ± 5.5% in FN, 7.7 ± 6% in TH, 2.0 ± 7.2% in LS, and 2.5 ± 6.4% in WB after 4 years, relative to baseline. Vitamin D levels increased with supplementation in both groups. Whereas parathyroid hormone levels increased slightly in the RYGB group, they decreased modestly in the SG group (P < 0.05 in both groups).

CONCLUSIONS

Bone loss after 4 years was comparable between the two procedures, although RYGB was associated with a slightly greater decrease at the TH than SG. Bone health should therefore be monitored after both RYGB and SG.

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.

A scoping review of the phenomenon of osteoporosis in post bariatric surgical patients

BACKGROUND

Risk factors, preventive treatment, and increased prevalence of fragility fractures in post-bariatric surgical patients have been researched, however, little is known about how patients' perspectives of osteoporosis risk determine their commitment to bone health.

PURPOSE

The purpose of this review was to provide an overview and appraisal of the research regarding osteoporosis in post bariatric surgical patients, as well as to identify gaps in the literature in this area.

METHODS

Data bases searched included OVID Medline, CINAHL, and EMBASE which included ahead of print articles that had not yet been indexed. Relevant key words were used independently and in combination: "osteoporosis," "morbid obesity," and "bariatric surgery."

RESULTS

A total of 24 quantitative studies and 15 qualitative studies were retrieved for this review; none of the qualitative studies examined both osteoporosis and bariatric surgery.

CONCLUSION

The current trend in bariatric surgical patients regarding osteoporosis is to examine the degree of bone loss based on significant influences including extent of weight loss, years since surgery, type of procedure performed, and subject selection. Patient perceptions about osteoporosis risk after bariatric surgery were rarely addressed.

Bone Density and Trabecular Morphology at Least 10 Years After Gastric Bypass and Gastric Banding

Roux-en-Y gastric bypass (RYGB) instigates high-turnover bone loss in the initial 5 years after surgery, whereas skeletal changes after adjustable gastric banding (AGB) are less pronounced. Long-term skeletal data are scarce, and the mechanisms of bone loss remain unclear. We sought to examine bone density and microarchitecture in RYGB and AGB patients a decade after surgery and to determine whether prior published reports of bone loss represent an appropriate adaptation to new postsurgical weight. In this cross-sectional study, 25 RYGB and 25 AGB subjects who had bariatric surgery ≥10 years ago were matched 1:1 with nonsurgical controls for age, sex, and current body mass index (BMI). We obtained bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), volumetric BMD and microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT), trabecular morphology by individual trabecular segmentation, and metabolic bone laboratory results. As compared with BMI-matched controls, RYGB subjects had significantly lower hip BMD, and lower total volumetric BMD at the distal radius and tibia. Substantial deficits in cortical and trabecular microarchitecture were observed in the RYGB group compared to controls, with reduced trabecular plate bone volume fraction and estimated failure load at both the radius and tibia, respectively. Bone turnover markers CTX and P1NP were 99% and 77% higher in the RYGB group than controls, respectively, with no differences in serum calcium, 25-hydroxyvitamin D, or parathyroid hormone. In contrast, the AGB group did not differ from their BMI-matched controls in any measured bone density, microarchitecture, or laboratory parameter. Thus, RYGB, but not AGB, is associated with lower than expected hip and peripheral BMD for the new weight setpoint, as well as deleterious changes in bone microarchitecture. These findings suggest that pathophysiologic processes other than mechanical unloading or secondary hyperparathyroidism contribute to bone loss after RYGB, and have important clinical implications for the long-term care of RYGB patients. © 2020 American Society for Bone and Mineral Research.

Effects of Sleeve Gastrectomy on Bone Marrow Adipose Tissue in Adolescents and Young Adults with Obesity

CONTEXT

Sleeve gastrectomy (SG), the most common metabolic and bariatric surgery in adolescents, is associated with bone loss. Marrow adipose tissue (MAT) is a dynamic endocrine organ that responds to changes in nutrition and might serve as a novel biomarker for bone health. Two types of MAT have been described, which differ in anatomic location-proximal regulated MAT vs distal constitutive MAT.

OBJECTIVE

To determine the effects of SG on volumetric bone mineral density (vBMD) and MAT in adolescents with obesity. We hypothesized that SG would lead to a decrease in vBMD and differential changes in MAT.

DESIGN

12-month prospective study in 52 adolescents with moderate-to-severe obesity (38 female; mean age:17.5 ± 2.2 years; mean BMI 45.2 ± 7.0 kg/m2), comprising 26 subjects before and after SG and 26 nonsurgical controls.

MAIN OUTCOME MEASURES

Lumbar vBMD by quantitative computed tomography; MAT of the lumbar spine, femur and tibia by proton magnetic resonance spectroscopy; abdominal fat and thigh muscle by magnetic resonance imaging.

RESULTS

Adolescents lost 34.1 ± 13.1 kg after SG vs 0.3 ± 8.4 kg in the control group (P < 0.001). Lumbar vBMD decreased in the SG group (P = 0.04) and this change was associated with a reduction in weight and muscle area (P < 0.05) and an increase in lumbar MAT (P = 0.0002). MAT of the femur and tibia decreased after SG vs controls (P < 0.05); however, the differences were no longer significant after controlling for change in weight.

CONCLUSION

SG in adolescents decreased lumbar vBMD associated with an increase in lumbar MAT and decrease in extremity MAT. This demonstrates differential changes of regulated MAT in the lumbar spine and constitutive MAT in the distal skeleton in adolescents in response to SG.

The Skeletal Consequences of Bariatric Surgery

PURPOSE OF REVIEW

This review outlines the recent findings regarding the impact of bariatric surgery on bone. It explores potential mechanisms for skeletal changes following bariatric surgery and strategies for management.

RECENT FINDINGS

Bone loss following bariatric surgery is multifactorial. Probable mechanisms include skeletal unloading, abnormalities in calciotropic hormones, and changes in gut hormones. Skeletal changes that occur after bariatric surgery are specific to procedure type and persist for several years post-operatively. Studies suggest that while bone loss begins early, fracture risk may be increased later in the post-operative course, particularly after Roux-en-Y gastric bypass (RYGB). Further research is needed to assess the extent to which skeletal changes following bariatric surgery result in fragility. Current management should be geared toward prevention of bone loss, correction of nutritional deficiencies, and incorporation of weight bearing exercise. Pharmacologic treatment should be considered for high-risk patients.

Clinical factors correlated with vitamin D deficiency in patients with obesity scheduled for bariatric surgery: A single center experience

We aim to assess the prevalence of vitamin D deficiency (VDD) in patients scheduled for bariatric surgery (BS), and to identify factors that might be associated with VDD. We conducted a cross-sectional observational study involving all consecutive patients scheduled for BS from 2017 to 2019. The exclusion criteria were missing data for vitamin D levels, intake of vitamin D supplements in the 3 months prior to serum vitamin D determination, and renal insufficiency. A total of 206 patients (mean age and body mass index [BMI] of 34.9 ± 10.7 years, and 44.3 ± 6.99 kg/m², respectively) met the inclusion criteria and were enrolled for data analysis. VDD (<19.9 ng/mL), severe VDD (<10 ng/mL), and vitamin D insufficiency (20-29.9 ng/mL) were present in 68.8 %, 12.5 %, and 31.2 % of patients, respectively. A significant inverse correlation was found between vitamin D levels and initial BMI, parathyroid hormone, and homeostatic model assessment of insulin resistance (r = -0.280, p < 0.05; r = -0.407, p = 0.038; r = -0.445, p = 0.005), respectively. VDD was significantly more prevalent in patients with higher BMI [-0.413 ± 0.12, CI95 % (-0.659; -0.167), p = 0.006], whereas no significant association between hypertension [-1.005 ± 1.65, CI95 % (-4.338; 2.326), p = 0.001], and diabetes type 2 (T2D) [-0.44 ± 2.20, CI95 % (-4.876; 3.986), p = 0.841] was found. We observed significant association between female sex and levels of vitamin D [6.69 ± 2.31, CI95 % (2.06; 11.33), p = 0.006]. The present study shows that in patients scheduled for BS, VDD deficiency is common and was associated with higher BMI, and female sex.

The Impact of Roux-en-Y Gastric Bypass on Bone Remodeling Expressed by the P1NP/βCTX Ratio: a Single-Center Prospective Cohort Study

BACKGROUND

Bariatric surgery seems to decrease bone mineral density and increase the risk of fatigue fractures. P1NP (bone formation) and βCTX (bone resorption) were recently validated as reference bone turnover markers (BTM).

OBJECTIVE

To assess changes in bone remodeling in severely obese patients undergoing Roux-en-Y gastric bypass (RYGB) by using a new composite biomarker, the P1NP/βCTX ratio.

METHODS

We prospectively collected blood samples preoperatively, at 1 month and at 1 year from 114 consecutive RYGB patients from 12/2012 to 04/2014. Repeated measures ANOVA and multiple regression were used for data analysis. Cumulative incidence of fractures was assessed in 06/2018.

RESULTS

The P1NP/βCTX ratio decreased significantly (P < 0.001) from baseline to 1 month and 1 year (180 ± 6.6, 110 ± 4.1, and 132 ± 5.4). The 1-year P1NP/βCTX ratio did not correlate with BMI or ΔBMI, but inversely correlated with age (r = - 0.23, P = 0.014) and with hsCRP (r = - 0.26, P = 0.009), even after adjustment for age, sex, BMI, and lifestyle, and linearly correlated with albumin (r = 0.2, P = 0.037). At baseline, none of these correlations were detectable. Serum for all time-points was available from > 94% of the patients. At a median follow-up of 4.7 years, 8 patients (7.3%) had a bone fracture, all of them traumatic.

CONCLUSION

Following RYGB, bone remodeling increases, with a shift toward degradation. This effect seems to be weight-loss independent and shows a correlation with age, with the level of systemic inflammation, and with nutritional state. The risk of fractures should be assessed systematically in bariatric patients and measures of prevention should be improved accordingly.

Serum Parathyroid Hormone and 25-Hydroxyvitamin D Concentrations Before and After Biliopancreatic Diversion

BACKGROUND

Biliopancreatic diversion with duodenal switch (BPD-DS) decreases vitamin D and calcium absorption, which may result in secondary hyperparathyroidism. This study aimed at evaluating the prevalence of vitamin D deficiency and secondary hyperparathyroidism before and after BPD-DS.

METHODS

A retrospective analysis of patients who had undergone BPD-DS at a tertiary bariatric center between 2003 and 2010 and for whom simultaneous measurements of serum 25-hydroxyvitamin D and parathyroid hormone were available within 5 years post-op was performed. The prevalence of vitamin D deficiency (< 20 ng/ml) and secondary hyperparathyroidism (> 65 pg/mL) at different time points was calculated.

RESULTS

Included were 1436 patients (mean ± SD, age 42.7 ± 10.4 years; BMI 51.5 ± 8.6 kg/m²; 69.8% women). Prevalence of vitamin D deficiency decreased up to 6-12 months after surgery (from 35.8% at baseline down to 6-9%) then rose progressively, plateauing at 15.5% after 36 months. Prevalence of hyperparathyroidism was 28.5% before surgery and rose progressively after surgery, reaching 68.6% at 5 years. Mean serum corrected calcium increased from 0 to 6 months then decreased up to 36 months. Preoperatively, the prevalence of hypocalcemia was 7.3%. It increased after 12 months, attaining 26.9% at 48 months.

CONCLUSIONS

Prevalence of vitamin D deficiency and secondary hyperparathyroidism is high before BPD-DS. Despite a low prevalence of vitamin D deficiency after surgery, prevalence of hyperparathyroidism increased steadily 1 year after surgery, preceded by a decrease in serum calcium. Factors explaining the high prevalence of secondary hyperparathyroidism after BPD-DS and its long-term impact on bone health should be addressed.

Endocrine implications of bariatric surgery: a review on the intersection between incretins, bone, and sex hormones

Bariatric surgery is now the most widely used intervention for the treatment of human obesity. A large body of literature has demonstrated its efficacy in sustained weight loss and improvement in its associated comorbidities. Here, we review the effect of bariatric surgery in gut hormone physiology, bone remodeling and the reproductive axis. Rapid improvements in insulin release and sensitivity appear to be weight loss independent and occur immediately after surgery. These effects on pancreatic beta cells are mostly due to increased gut hormone secretion due to augmented nutrient delivery to the small intestine. Bone remodeling is also affected by gut hormones. Phenotypic skeletal changes observed in mice deficient in GLP-1 or GIP suggest that increased incretins may improve bone density. However, these positive effects may be counterbalanced by the association between weight loss and a reduction in bone density. Finally, studies have shown a marked improvement following bariatric surgery in infertility and PCOS in women and hypogonadism in men. Thus, the net effect on endocrine systems after bariatric surgery will likely vary on an individual basis and depend on factors such as comorbidities, peri-menopausal state, amount of weight loss, and likelihood to adhere to vitamin supplementation after surgery.

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.

Transient osteoporosis of the hip after bariatric surgery

Transient osteoporosis is a rare manifestation of acute hip pain which typically resolves with weight-bearing restrictions and pain management. Our case report presents a patient who experienced atraumatic right hip pain a few weeks after an uncomplicated bariatric surgery and was diagnosed with transient osteoporosis of the hip. Her condition resolved after weeks of protected weight-bearing restrictions and nonsteroidal anti-inflammatories. Transient osteoporosis should be considered in the differential diagnosis of hip pain in patients who have undergone previous bariatric surgery.

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.

CHANGES IN BONE MINERAL PARAMETERS AFTER SLEEVE GASTRECTOMY: RELATIONSHIP WITH GHRELIN AND PLASMA ADIPOKINE LEVELS

CONTEXT

Metabolic surgery is currently the most efficient treatment for obesity, but concern is raised about the possible long-term nutritional side effects. Bone metabolism is often adversely affected after surgery, but literature data are contradictory.

OBJECTIVE

The aim of this study was to evaluate the evolution of bone mass parameters in the first year after laparoscopic sleeve gastrectomy in relation to anthropometric and body composition parameters and specific hormones of obesity.

DESIGN

We conducted a prospective study on 75 patients with obesity that underwent metabolic surgery over a course of 18 months at our center, with a follow-up period of 12 months.

SUBJECTS AND METHODS

All patients underwent a complex preoperative assessment and were required to return for medical follow-up at 6 and 12 months after surgery. Each visit included anthropometric parameters, DEXA and determination of specific hormonal parameters.

RESULTS

We noticed a significant improvement in anthropometric and body composition parameters after surgery. The value of adiponectin presented a significant increase after surgery and leptin showed a significant decrease at 6 and 12 months postoperative; ghrelin level decreased postoperative compared to preoperative, but without statistical significance. We observed no reduction in BMD after surgery, but a significant improvement in BMC at 12 months after surgery compared to preoperative. Ghrelin negatively correlated to BMD preoperative.

CONCLUSIONS

Despite the significant alterations in anthropometric, body composition and hormonal parameters, we found no negative effect on BMD and BMC in our study population.

Impact of bariatric surgery on bone tissue

The important prevalence and morbidity of obesity has generated an increase in bariatric surgery. It has a positive effect in obesity-related comorbidities. However, it's detrimental to bone health. The underline pathophysiological mechanisms are complex and heterogeneous. The knowledge of these factors may lead us to develop an adequate therapeutic intervention.

Effects of Gastric Bypass Surgery on Bone Mass and Microarchitecture Occur Early and Particularly Impact Postmenopausal Women

Roux-en-Y gastric bypass (RYGB) surgery is a highly effective treatment for obesity but negatively affects the skeleton. Studies of skeletal effects have generally examined areal bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), but DXA may be inaccurate in the setting of marked weight loss. Further, as a result of modestly sized samples of mostly premenopausal women and very few men, effects of RYGB by sex and menopausal status are unknown. We prospectively studied the effects of RYGB on skeletal health, including axial and appendicular volumetric BMD and appendicular bone microarchitecture and estimated strength. Obese adults (N = 48; 27 premenopausal and 11 postmenopausal women, 10 men) with mean ± SD body mass index (BMI) 44 ± 7 kg/m² were assessed before and 6 and 12 months after RYGB. Participants underwent spine and hip DXA, spine QCT, radius and tibia HR-pQCT, and laboratory evaluation. Mean 12-month weight loss was 37 kg (30% of preoperative weight). Overall median 12-month increase in serum collagen type I C-telopeptide (CTx) was 278% (p < 0.0001), with greater increases in postmenopausal than premenopausal women (p = 0.049). Femoral neck BMD by DXA decreased by mean 5.0% and 8.0% over 6 and 12 months (p < 0.0001). Spinal BMD by QCT decreased by mean 6.6% and 8.1% (p < 0.0001); declines were larger among postmenopausal than premenopausal women (11.6% versus 6.0% at 12 months, p = 0.02). Radial and tibial BMD and estimated strength by HR-pQCT declined. At the tibia, detrimental changes in trabecular microarchitecture were apparent at 6 and 12 months. Cortical porosity increased at the radius and tibia, with more dramatic 12-month increases among postmenopausal than premenopausal women or men at the tibia (51.4% versus 18.3% versus 3.0%, p < 0.01 between groups). In conclusion, detrimental effects of RYGB on axial and appendicular bone mass and microarchitecture are detectable as early as 6 months postoperatively. Postmenopausal women are at highest risk for skeletal consequences and may warrant targeted screening or interventions. © 2017 American Society for Bone and Mineral Research.

A meta-analysis of the effects of bariatric surgery on fracture risk

Bariatric surgery effectively treats morbid obesity. However, the negative effect of this surgery on the bone is concerning. The aim of this meta-analysis was to investigate the fracture risk associated with bariatric surgery in morbidly obese subjects. Relevant studies published from database inception to September 2017 were identified in PubMed, Embase and the Cochrane Library. The Newcastle-Ottawa Scale was used to evaluate the quality of the observational studies, and the Jadad score evaluated randomized controlled trials. Among the 1003 studies initially identified, five observational trials and one randomized controlled trial were eligible for inclusion. All studies included in the meta-analysis were considered high quality. Risk for any type of fracture was higher in the surgical group than in the non-surgical group (risk ratio [RR] 1.29, 95% confidence interval [CI] 1.18-1.42). After surgery, the fracture risk in non-vertebral sites was significantly increased, especially in the upper limbs (RR 1.42, 95% CI 1.08-1.87; and RR 1.68, 95% CI 1.15-2.45). Compared with those with restrictive procedures, subjects who underwent mixed restrictive and malabsorptive procedures tended to have an increased fracture risk (RR 1.54, 95% CI 0.96-2.46). To conclude, bariatric surgery is associated with an increased risk of total and non-vertebral fractures, especially in the upper limbs.

Unraveling the compromised biomechanical performance of type 2 diabetes- and Roux-en-Y gastric bypass bone by linking mechanical-structural and physico-chemical properties

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with obesity and hyperglycemia. Roux-en-Y gastric bypass (RYGB) surgery is a common treatment for severely obese patients and T2DM. Both RYGB and T2DM are linked to increased skeletal fragility, though the exact mechanisms are poorly understood. Our aim was to characterize the structural, mechanical and compositional properties of bones from diet-induced obese and RYGB-treated obese (bypass) mice to elucidate which the exact factors are contributing to the increased skeletal fragility. To achieve this, a combinatory approach including microfocus X-ray computed tomography, 3-point bending, finite element modeling and Raman spectroscopy, was used. Compared to aged-matched lean controls, the obese mice displayed decreased cortical thickness, trabecular bone loss, decreased stiffness and increased Young’s modulus. For the bypass mice, these alterations were even more pronounced, and additionally they showed low mineral-to-matrix ratio in the cortical endosteal area. Accumulation of the advanced glycation end-product (AGE) pentosidine was found in the cortex of obese and bypass groups and this accumulation was correlated with an increased Young’s modulus. In conclusion, we found that the increased fracture risk in T2DM- and post-RYGB bones is mainly driven by accumulation of AGEs and macro-structural alterations, generating biomechanical dysfunctionality.

Vitamin D Metabolism in Bariatric Surgery

Hypovitaminosis D is common in obese patients and persists after roux-en-Y gastric bypass and sleeve gastrectomy. Several societies recommend screening for vitamin D deficiency before bariatric surgery, and replacement doses of 3000 IU/d and up to 50,000 IU 1 to 3 times per week, in case of deficiency, with periodic monitoring. These regimens are mostly based on expert opinion. Large trials are needed to assess the vitamin D dose response, by type of bariatric surgery, and evaluate the effect on surrogate markers of skeletal outcomes. Such data are essential to derive desirable vitamin D levels in this population.

INCREASED BONE TURNOVER IN TYPE 2 DIABETES PATIENTS RANDOMIZED TO BARIATRIC SURGERY VERSUS MEDICAL THERAPY AT 5 YEARS

OBJECTIVE

The aim of our study was to determine the 5-year outcomes of bariatric surgery versus intensive medical therapy on bone turnover in patients with type 2 diabetes mellitus (T2DM) from the STAMPEDE trial.

METHODS

This was an ancillary investigation of a 5-year randomized control trial at a single tertiary care center involving 95 patients aged 48.5 ± 8 years with obesity (body mass index [BMI], 36.5 ± 3.6 kg/m²) and uncontrolled T2DM (glycated hemoglobin 9.3 ± 1.6% [78 mmol/mol]). Patients were randomized to intensive medical therapy (IMT; n = 25), Roux-en-Y gastric bypass (RYGB; n = 37), or sleeve gastrectomy (SG; n = 33) for diabetes treatment. Bone formation marker osteocalcin (OC), bone resorption marker serum C-telopeptide of type 1 collagen (CTX), and intact parathyroid hormone (PTH) were assessed at baseline and 5 years postintervention. Analysis with key clinical parameters and outcomes (i.e., age, menopausal status, gender, weight loss) was performed.

RESULTS

Percent change in CTX at 5 years increased in both surgical groups, by 137 ± 108% in RYGB ( P<.001) and 61.1 ± 90% in SG ( P<.001) compared to 29.8 ± 93% in IMT ( P = .12). OC also increased from baseline in the surgical cohorts, by 138 ± 19% in RYGB ( P<.001) and 71 ± 69% in SG ( P<.001) compared to 43.8 ± 121.1% in IMT ( P = .83). Increases in both CTX and OC correlated linearly with increases in PTH levels in RYGB patients ( P<.001). Increase in CTX correlated with decreased BMI in SG patients ( P = .039).

CONCLUSION

In patients with T2DM, bone turnover remains chronically elevated at 5 years following RYGB, and to a lesser extent in SG patients.

ABBREVIATIONS

BMI = body mass index; BTM = bone turnover marker; CTX = C-telopeptide of type 1 collagen; HbA1c = glycated hemoglobin; IMT = intensive medical therapy; OC = osteocalcin; PPI = proton-pump inhibitor; PTH = parathyroid hormone; RYGB = Roux-en-Y gastric bypass; SG = sleeve gastrectomy; T2DM = type 2 diabetes mellitus; TZD = thiazolidinedione.

Bariatric surgery and long-term nutritional issues

Bariatric surgery is recognized as a highly effective therapy for obesity since it accomplishes sustained weight loss, reduction of obesity-related comorbidities and mortality, and improvement of quality of life. Overall, bariatric surgery is associated with a 42% reduction of the cardiovascular risk and 30% reduction of all-cause mortality. This review focuses on some nutritional consequences that can occur in bariatric patients that could potentially hinder the clinical benefits of this therapeutic option. All bariatric procedures, to variable degrees, alter the anatomy and physiology of the gastrointestinal tract; this alteration makes these patients more susceptible to developing nutritional complications, namely, deficiencies of macro- and micro-nutrients, which could lead to disabling diseases such as anemia, osteoporosis, protein malnutrition. Of note is the evidence that most obese patients present a number of nutritional deficits already prior to surgery, the most important being vitamin D and iron deficiencies. This finding prompts the need for a complete nutritional assessment and, eventually, an adequate correction of pre-existing deficits before surgery. Another critical issue that follows bariatric surgery is post-operative weight regain, which is commonly associated with the relapse of obesity-related co-morbidities. Nu-tritional complications associated with bariatric surgery can be prevented by life-long nutritional monitoring with the administration of multi-vitamins and mineral supplements according to the patient's needs.

A Systematic Review: Vitamin D Status and Sleeve Gastrectomy

BACKGROUND

Bariatric patients regularly present with insufficient vitamin D status before and after surgery, which requires substantial supplementation to treat. This review aims to assess the effect of sleeve gastrectomy on vitamin D status and the effectiveness of vitamin D supplementation.

METHODS

This review was conducted in accordance with the Guidelines for Meta-Analyses and Systematic Reviews of Observational Studies.

RESULTS

The current guidelines recommend initial vitamin D supplementation of at least 3000 IU/day post-operatively, with no need for follow-up testing after sleeve gastrectomy. Only one study has trialled a dose in line with the recommendations for this patient group. They found that it was effective in improving VitD status.

CONCLUSIONS

On-going monitoring of vitamin D status is necessary, as the recommended level is not often reached.

Vitamin D and intestinal calcium transport after bariatric surgery

Bariatric surgery is a highly effective treatment for obesity, but it may have detrimental effects on the skeleton. Skeletal effects are multifactorial but mediated in part by nutrient malabsorption. While there is increasing interest in non-nutritional mechanisms such as changes in fat-derived and gut-derived hormones, nutritional factors are modifiable and thus represent potential opportunities to prevent and treat skeletal complications. This review begins with a discussion of normal intestinal calcium transport, including recent advances in our understanding of its regulation by vitamin D, and areas of continued uncertainty. Human and animal studies of vitamin D and intestinal calcium transport after bariatric surgery are then summarized. In humans, even with optimized 25-hydroxyvitamin D levels and recommended calcium intake, fractional calcium absorption decreased dramatically after Roux-en-Y gastric bypass (RYGB). In rats, intestinal calcium absorption was lower after RYGB than after sham surgery, despite elevated 1,25-dihyroxyvitamin D levels and intestinal gene expression evidence of vitamin D responsiveness. Such studies have the potential to shed new light on the physiology of vitamin D and intestinal calcium transport. Moreover, understanding the effects of bariatric surgery on these processes may improve the clinical care of bariatric surgery patients.

LONG-TERM BONE HEALTH AFTER ROUX-EN-Y GASTRIC BYPASS: A PILOT STUDY

OBJECTIVE

This cross-sectional study was undertaken to assess metabolic bone disease by examining bone mineral density (BMD), fracture prevalence, and nutritional factors pertinent to bone in a cohort >9 years post-Rouxen-Y gastric bypass (RYGB).

METHODS

Fifty-one subjects 9.4 to 36.0 years (mean 17.0 ± 8.1) post-RYGB provided a focused history. Dietary calcium and protein were assessed. Dual-energy X-ray absorptiometry (DXA) BMD at the spine, hip, and radius and routine serum chemistries, magnesium, phosphorus, parathyroid hormone, vitamin D, vitamin K, and micronutrients were analyzed. Sixteen subjects provided 24-hour urine for measurement of calcium.

RESULTS

The mean maximum weight loss was 70.3 ± 20 kg (47.4 ± 8.9%), and mean net weight loss was 46.9 ± 23.1 kg (31.2 ± 12.5%). The prevalence rates of fracture, secondary hyperparathyroidism, and vitamin D deficiency were 15.7%, 37%, and 39%, respectively. BMD was in the osteoporotic range in 27.5%. The mean calcium:creatinine clearance ratio was 0.0124 ± 0.0131. Median intakes of dietary calcium, total calcium, protein, and vitamin D were 582.5 mg, 947.5 mg, 50.2 g, and 1,000 IU, respectively. Mean Z-scores at all sites were <0 (P<.01). A negative correlation (P<.05) was noted between distal radius Z-score and net change in BMI. Net change in BMI was greater for those with osteoporosis than those without. (P<.05) Conclusion: Many years after RYGB, BMD remains lower than expected compared to an age-, sex-, race-, and weight-matched reference population and is correlated with the amount of weight lost. Deficiencies of Vitamin D and calcium are prevalent.

ABBREVIATIONS

BMD = bone mineral density BMI = body mass index Ca:Cr = calcium:creatinine DXA = dual-energy X-ray absorptiometry PTH = parathyroid hormone RYGB = Roux-en-Y gastric bypass UD = ultradistal WHO = World Health Organization.

Fracture Risk After Bariatric Surgery: Roux-en-Y Gastric Bypass Versus Adjustable Gastric Banding

The long-term consequences of bariatric surgery on fracture risk are unclear but are likely to vary by procedure type. In physiologic studies, Roux-en-Y gastric bypass (RYGB) and adjustable gastric banding (AGB) have differential effects on rates of bone loss. Therefore, our objective was to compare fracture risk in obese adults after RYGB and AGB procedures. Using claims data from a US commercial health plan, we analyzed rates of nonvertebral fractures within a propensity score-matched cohort (n = 15,032) of morbidly obese adults who received either RYGB or AGB surgery between 2005 and 2013. A total of 281 nonvertebral fractures occurred during a mean follow-up time of 2.3 ± 1.9 years. RYGB patients had an increased risk of nonvertebral fracture (hazard ratio [HR] = 1.43, 95% confidence interval [CI] 1.13-1.81) compared with AGB patients. In fracture site-specific analyses, RYGB patients had increased risk of fracture at the hip (HR = 1.54, 95% CI 1.03-2.30) and wrist (HR = 1.45, 95% CI 1.01-2.07). Nonvertebral fracture risk associated with RYGB manifested >2 years after surgery and increased in subsequent years, with the highest risk in the fifth year after surgery (HR = 3.91, 95% CI 1.58-9.64). In summary, RYGB is associated with a 43% increased risk of nonvertebral fracture compared with AGB, with risk increasing >2 years after surgery. Fracture risk should be considered in risk/benefit discussions of bariatric surgery, particularly among patients with high baseline risk of osteoporosis who are deciding between RYGB and AGB procedures. © 2017 American Society for Bone and Mineral Research.

Hypocalcemia and osteomalacia after bariatric surgery

INTRODUCTION

Obesity has become a major health problem not only in industrialized societies but also in developing countries. Multiple studies have shown that bariatric surgery has been effective in reducing substantial amount of weight and also the comorbidities and is being performed more frequently as an established treatment. Due to anatomical and physiological alterations after surgery that impairs absorption of vitamin D and calcium, two fundamental factors in bone formation, their intestinal absorption is highly compromised.

CASE REPORT

We present a 48-year-old woman who was visited in emergency room for generalized bone pain, perioral paresthesia and carpopedal spasm. She had undergone bariatric surgery 15 years ago. Chvostek's sign and Trousseau's sign were positive. Examination of thoracic ribs elicited severe pain on palpation. Laboratory evaluation revealed: Ca = 6.1 mg/dL, P= 2.1 mg/dL, alkaline phosphatase = 432 (160-303), PTH=541 pg/mL, and 25(OH)D3= 3 ng/mL. Whole body bone scan showed increased uptake in the anterior arc of left 6th rib, posterior arc of left 6th and 12th ribs with increased uptake of costochondral joints.

CONCLUSION

Our case highlights the possible consequences that bariatric surgery may have on bone and mineral health and the need for regular and proactive follow-up of the patients.

Bilateral insufficiency hip fractures after bariatric surgery

Bariatric surgery is one of the most common surgeries within developed countries due to the increase in morbid obesity that has been observed in the past decades. The short-term alterations in the metabolism of calcium and vitamin D are well known after these procedures; however, the clinical and biochemical consequences may not be detected for years or even remain undiagnosed. We present the first case of bilateral insufficiency hip fracture after years of bariatric surgery. Although this is a long-term and rare complication, with the high number of gastric bypass performed in the past years, the number of these cases could increase with time. Moreover, it is important as an undiagnosed hip fracture can cause a displacement that could need an arthroplasty, with all the complications that entails. For that reason, this long-term complication highlights the need to reevaluate the optimal follow-up of these patients and the importance to continue monitoring metabolic bone diseases in the prevention of insufficiency fractures.

Effects of obesity treatments on bone mineral density, bone turnover and fracture risk in adults with overweight or obesity

BACKGROUND

New evidence suggests that obesity is deleterious for bone health, and obesity treatments could potentially exacerbate this.

MATERIALS AND METHODS

This narrative review, largely based on recent systematic reviews and meta-analyses, synthesizes the effects on bone of bariatric surgery, weight loss pharmaceuticals and dietary restriction.

RESULTS AND CONCLUSIONS

All three obesity treatments result in statistically significant reductions in hip bone mineral density (BMD) and increases in bone turnover relative to pre-treatment values, with the reductions in hip BMD being strongest for bariatric surgery, notably Roux-en Y gastric bypass (RYGB, 8%-11% of pre-surgical values) and weakest for dietary restriction (1%-1.5% of pre-treatment values). Weight loss pharmaceuticals (orlistat or the glucagon-like peptide-1 receptor agonist, liraglutide) induced no greater changes from pre-treatment values than control, despite greater weight loss. There is suggestive evidence that liraglutide may increase bone mineral content (BMC) - but not BMD - and reduce fracture risk, but more research is required to clarify this. All three obesity treatments have variable effects on spine BMD, probably due to greater measurement error at this site in obesity, suggesting that future research in this field could focus on hip rather than spine BMD. Various mechanisms have been proposed for BMD loss with obesity treatments, notably reduced nutritional intake/absorption and insufficient exercise, and these are potential avenues for protection against bone loss. However, a pressing outstanding question is whether this BMD reduction contributes to increased fracture risk, as has been observed after RYGB, and whether any such increase in fracture risk outweighs the risks of staying obese (unlikely).

Effects of Roux-en-Y gastric bypass and sleeve gastrectomy on bone mineral density and marrow adipose tissue

Bariatric surgery is associated with bone loss but skeletal consequences may differ between Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), the two most commonly performed bariatric procedures. Furthermore, severe weight loss is associated with high marrow adipose tissue (MAT); however, MAT is also increased in visceral adiposity. The purpose of our study was to determine the effects of RYGB and SG on BMD and MAT. We hypothesized that both bariatric procedures would lead to a decrease in BMD and MAT. We studied 21 adults with morbid obesity (mean BMI 44.1±5.1kg/m²) prior to and 12months after RYGB (n=11) and SG (n=10). All subjects underwent DXA and QCT of the lumbar spine and hip to assess aBMD and vBMD. Visceral (VAT) and subcutaneous (SAT) adipose tissue was quantified at L1-L2. MAT of the lumbar spine and femur was assessed by 1H-MR spectroscopy. Calcitropic hormones and bone turnover markers were determined. At 12months after surgery, mean weight and abdominal fat loss was similar between the RYGB and SG groups. Mean serum calcium, 25(OH)-vitamin D, and PTH levels were unchanged after surgery and within the normal range in both groups. Bone turnover markers P1NP and CTX increased within both groups and P1NP increased to a greater extent in the RYGB group (p=0.03). There were significant declines from baseline in spine aBMD and vBMD within the RYGB and SG groups, although the changes were not significantly different between groups (p=0.3). Total hip and femoral neck aBMD by DXA decreased to a greater extent in the RYGB than the SG group (p<0.04) although the change in femoral vBMD by QCT was not significantly different between groups (p>0.2). MAT content of the lumbar spine and femoral diaphysis did not change from baseline in the RYGB group but increased after SG (p=0.03). Within the SG group, 12-month change in weight and VAT were positively associated with 12-month change in MAT (p<0.04), suggesting that subjects with less weight and VAT loss had higher MAT. In conclusion, RYGB and SG are associated with declines in lumbar spine BMD, however, the changes are not significantly different between the groups. RYGB may be associated with greater decline of aBMD at the total hip and femoral neck compared to SG. MAT content increased after SG and this was associated with lower weight and VAT loss.

Change in fracture risk and fracture pattern after bariatric surgery: nested case-control study

OBJECTIVE

 To investigate whether bariatric surgery increases the risk of fracture.

DESIGN

 Retrospective nested case-control study.

SETTING

 Patients who underwent bariatric surgery in the province of Quebec, Canada, between 2001 and 2014, selected using healthcare administrative databases.

PARTICIPANTS

 12 676 patients who underwent bariatric surgery, age and sex matched with 38 028 obese and 126 760 non-obese controls.

MAIN OUTCOME MEASURES

 Incidence and sites of fracture in patients who had undergone bariatric surgery compared with obese and non-obese controls. Fracture risk was also compared before and after surgery (index date) within each group and by type of surgery from 2006 to 2014. Multivariate conditional Poisson regression models were adjusted for fracture history, number of comorbidities, sociomaterial deprivation, and area of residence.

RESULTS

 Before surgery, patients undergoing bariatric surgery (9169 (72.3%) women; mean age 42 (SD 11) years) were more likely to fracture (1326; 10.5%) than were obese (3065; 8.1%) or non-obese (8329; 6.6%) controls. A mean of 4.4 years after surgery, bariatric patients were more susceptible to fracture (514; 4.1%) than were obese (1013; 2.7%) and non-obese (3008; 2.4%) controls. Postoperative adjusted fracture risk was higher in the bariatric group than in the obese (relative risk 1.38, 95% confidence interval 1.23 to 1.55) and non-obese (1.44, 1.29 to 1.59) groups. Before surgery, the risk of distal lower limb fracture was higher, upper limb fracture risk was lower, and risk of clinical spine, hip, femur, or pelvic fractures was similar in the bariatric and obese groups compared with the non-obese group. After surgery, risk of distal lower limb fracture decreased (relative risk 0.66, 0.56 to 0.78), whereas risk of upper limb (1.64, 1.40 to 1.93), clinical spine (1.78, 1.08 to 2.93), pelvic, hip, or femur (2.52, 1.78 to 3.59) fractures increased. The increase in risk of fracture reached significance only for biliopancreatic diversion.

CONCLUSIONS

 Patients undergoing bariatric surgery were more likely to have fractures than were obese or non-obese controls, and this risk remained higher after surgery. Fracture risk was site specific, changing from a pattern associated with obesity to a pattern typical of osteoporosis after surgery. Only biliopancreatic diversion was clearly associated with fracture risk; however, results for Roux-en-Y gastric bypass and sleeve gastrectomy remain inconclusive. Fracture risk assessment and management should be part of bariatric care.

Fracture Risk After Bariatric Surgery: A 12-Year Nationwide Cohort Study

Bariatric surgery has been shown to impair bone health. This study aimed to investigate the fracture risk in patients after bariatric surgery versus propensity score-matched controls. The authors used the National Health Insurance Research Database of Taiwan and identified 2064 patients who underwent bariatric surgery during 2001 to 2009. These patients were matched to 5027 obese patients who did not receive bariatric surgery, using propensity score matching accounting for age, sex, Charlson Comorbidity Index, diabetes, hypertension, hyperlipidemia and the year morbid obesity was diagnosed. The authors followed the surgical and control cohorts to death, any diagnosis of fracture, or December 31, 2012, whichever occurred first. Cox proportional hazard regression models were used to calculate relative rates of fractures in the surgical group and control group. At the end of the 12-year study period, there were 183 fractures in the surgical group (mean follow-up 4.8 years) and 374 fractures in the matched control group (mean follow-up 4.9 years). Overall, there was a 1.21-fold [95% confidence interval (CI): 1.02-1.43] significantly increased risk of fracture in the surgical group compared with the control group. Stratified by surgical procedures, malabsorptive procedures showed a significantly higher fracture risk (1.47, 95% CI: 1.01-2.15). The Kaplan-Meier estimated fracture rates were 1.60% at 1 year, 2.37% at 2 years, 1.69% at 5 years, and 2.06% after 5 years for the surgical patients, compared with 1.51%, 1.65%, 1.53%, and 1.42%, respectively, for the matched controls. Adjusted analysis showed a trend towards an increased fracture risk, 1 to 2 years after bariatric surgery. (1.42, 95% CI: 0.99-2.05). Bariatric surgery was significantly associated with an increased risk of fractures, mainly with malabsorptive procedures, with a trend of an increased fracture risk 1 to 2 years after surgery. These results provide further evidence for the adverse effects of bariatric surgery on the risk of fractures.

Two-year changes in bone density after Roux-en-Y gastric bypass surgery

CONTEXT

Bariatric surgery is increasingly popular but may lead to metabolic bone disease.

OBJECTIVE

The objective was to determine the rate of bone loss in the 24 months after Roux-en-Y gastric bypass.

DESIGN AND SETTING

This was a prospective cohort study conducted at an academic medical center.

PARTICIPANTS

The participants were adults with severe obesity, including 30 adults undergoing gastric bypass and 20 nonsurgical controls.

OUTCOMES

We measured bone mineral density (BMD) at the lumbar spine and proximal femur by quantitative computed tomography (QCT) and dual-energy x-ray absorptiometry at 0, 12, and 24 months. BMD and bone microarchitecture were also assessed by high-resolution peripheral QCT, and estimated bone strength was calculated using microfinite element analysis.

RESULTS

Weight loss plateaued 6 months after gastric bypass but remained greater than controls at 24 months (-37 ± 3 vs -5 ± 3 kg [ mean ± SEM]; P < .001). At 24 months, BMD was 5-7% lower at the spine and 6-10% lower at the hip in subjects who underwent gastric bypass compared with nonsurgical controls, as assessed by QCT and dual-energy x-ray absorptiometry (P < .001 for all). Despite significant bone loss, average T-scores remained in the normal range 24 months after gastric bypass. Cortical and trabecular BMD and microarchitecture at the distal radius and tibia deteriorated in the gastric bypass group throughout the 24 months, such that estimated bone strength was 9% lower than controls. The decline in BMD persisted beyond the first year, with rates of bone loss exceeding controls throughout the second year at all skeletal sites. Mean serum calcium, 25(OH)-vitamin D, and PTH were maintained within the normal range in both groups.

CONCLUSIONS

Substantial bone loss occurs throughout the 24 months after gastric bypass despite weight stability in the second year. Although the benefits of gastric bypass surgery are well established, the potential for adverse effects on skeletal integrity remains an important concern.

Obesity and weight loss could alter the properties of adipose stem cells?

The discovery that adipose tissue represents an interesting source of multipotent stem cells has led to many studies exploring the clinical potential of these cells in cell-based therapies. Recent advances in understanding the secretory capacity of adipose tissue and the role of adipokines in the development of obesity and associated disorders have added a new dimension to the study of adipose tissue biology in normal and diseased states. Subcutaneous adipose tissue forms the interface between the clinical application of regenerative medicine and the establishment of the pathological condition of obesity. These two facets of adipose tissue should be understood as potentially related phenomena. Because of the functional characteristics of adipose stem cells, these cells represent a fundamental tool for understanding how these two facets are interconnected and could be important for therapeutic applications. In fact, adipose tissue stem cells have multiple functions in obesity related to adipogenic, angiogenic and secretory capacities. In addition, we have also previously described a predominance of larger blood vessels and an adipogenic memory in the subcutaneous adipose tissue after massive weight loss subsequent to bariatric surgery (ex-obese patients). Understanding the reversibility of the behavior of adipose stem cells in obeses and in weight loss is relevant to both physiological studies and the potential use of these cells in regenerative medicine.