Effect of Sleeve Gastrectomy on Bone Metabolism and Serum 5-Hydroxytryptamine in Obese Rats

Bone Composition Changes and Calcium Metabolism in Obese Adolescents and Young Adults Undergoing Sleeve Gastrectomy: A Systematic Review

Background/Objectives: Sleeve gastrectomy (SG) is increasingly used to treat severe obesity in adolescents, but its effects on bone health during this critical period of bone accrual are not fully understood. This systematic review aims to evaluate the impact of SG on the bone mineral density (BMD), bone microarchitecture, marrow adipose tissue (MAT), and bone turnover markers in adolescents. Methods: A comprehensive literature search was conducted to identify studies assessing bone health outcomes in adolescents undergoing SG. Nine studies met the inclusion criteria, comprising prospective cohorts, observational cohorts, and one randomized controlled trial, with sample sizes ranging from 10 to 197 participants aged 13 to 25 years, and a total sample size of 597 individuals. Data were extracted and synthesized into tables summarizing changes in BMD, bone microarchitecture, MAT, and bone turnover markers. Results: SG in adolescents is associated with significant reductions in areal BMD at critical skeletal sites, particularly the femoral neck and total hip, with decreases ranging from -4.7% to -8.9%. Studies utilizing high-resolution peripheral quantitative computed tomography (HRpQCT) reported deteriorations in bone microarchitecture, including a decreased trabecular number, increased trabecular separation, and reduced cortical thickness. Two studies observed significant increases in MAT at the lumbar spine post-SG. Elevated bone turnover markers, particularly C-terminal cross-linking telopeptide (CTX), indicate increased bone resorption following SG. Conclusions: SG leads to negative effects on bone health in adolescents, including reductions in BMD, deterioration of the bone microarchitecture, increases in MAT, and elevated bone resorption markers. These findings highlight the need for careful monitoring of bone health and the development of strategies to mitigate bone loss in adolescents undergoing SG.

Effect of Laparoscopic Sleeve Gastrectomy on Calcium Metabolism Parameters, Vitamin D, and Parathyroid Hormone in Morbidly Obese Patients: Short-Term Results

OBJECTIVE

Sleeve gastrectomy (SG) is a widely utilized bariatric surgical procedure. It may affect various aspects of nutritional and metabolic health, including calcium (Ca) metabolism, vitamin D levels, and parathyroid hormone (PTH) secretion. We aimed to investigate the effect of laparoscopic SG (LSG) on Ca metabolism parameters, vitamin D, and PTH in morbidly obese patients.

MATERIALS AND METHODS

This single-center, retrospective cohort study was conducted at the Department of General Surgery, Avrupa Safak Hospital, Istanbul, between March 2021 and November 2023. A total of 78 patients were included in the study. The procedure involved the resection of approximately 80% of the stomach, creating a tubular gastric sleeve. All patients underwent postoperative follow-up at six and 12 months.

RESULTS

Of the 78 patients, 49 (62.8%) were females and 29 (37.1%) were males. The mean age of the patients was 31.2±9.8 years. The mean weight was 126±12.2 kg and the mean BMI was 47±6.9 kg/m2. There was a significant decrease in the BMI values following surgery (p<0.01). Vitamin D level was found to be 18.7±4.2 ng/mL at baseline, which increased to 37.6±2.5 ng/mL at 12 months after surgery (p<0.01). Before surgery, the PTH level was 69.1±8.7 pg/mL, which decreased to 39.3±5.5 pg/mL at 12 months postoperatively (p<0.01). The mean serum Ca level at baseline was 9.2±1.4 mg/dL, which increased to 10.1±0.4 mg/dL at 12 months after operation (p<0.01).

CONCLUSION

Our study results suggest that low vitamin D levels are commonly observed in patients undergoing bariatric surgery. Administering vitamin D as a standard postoperative treatment regimen may be helpful in reducing this deficiency. We, therefore, recommend continuous monitoring of vitamin D, PTH, and serum Ca levels after surgery to manage these issues effectively.

Effects of sleeve gastrectomy on bone mass, microstructure of femurs and bone metabolism associated serum factors in obese rats

BACKGROUND

Sleeve gastrectomy (SG) is a profoundly effective operation for severe obese patients, but is closely associated with bone mass loss. Previous studies have reported changes of various serum factors which may be associated with bone mass loss after SG. However, those results are contradictory. In this study, we assessed the effects of SG on bone mass, microstructure of femurs, and changes in bone turnover markers (BTMs), serum adipokines, inflammatory factors and gastrointestinal hormones after SG in high-fat diet (HFD) induced obese rats.

METHODS

Eight-week-old male Sprague-Dawley (SD) rats were fed with HFD to induce obesity. Then, SG and sham surgery were performed in anesthetized obese rats. SD rats in control group were fed with standard chow. Microstructure of femurs was scanned and analyzed by micro-computed tomography in control group, HFD sham group and HFD SG group. Serum inflammatory factors, adipokines markers, gastrointestinal hormones and BTMs were also measured.

RESULTS

Bone mineral density (BMD) of trabecular bone in both HFD sham group and HFD SG group were remarkably decreased compared with control group. All serum BTMs were significantly higher in HFD SG group than HFD sham group. In the meantime, serum levels of several important inflammatory factors, gastrointestinal hormones and adipokines such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, monocyte chemoattractant protein-1(MCP-1), ghrelin, insulin and leptin in HFD SG group were remarkably reduced compared with HFD sham group, whereas glucagon-like peptide-1 (GLP-1), adiponectin, fibroblast growth factor (FGF)-19 and FGF-21 were dramatically increased after SG. Protein tyrosine phosphatase 1B (PTP1B) was significantly increased in the HFD sham group than control group. Spearman's correlation analysis indicated that serum osteocalcin (OC) and 25-hydroxy vitamin D₃ (25(OH)D₃) were positively correlated with BMD of trabecular bone, whereas serum PTP1B and TNF-α were negatively related to BMD of trabecular bone.

CONCLUSIONS

SG aggravates bone mass loss and activates bone remodeling in obese rats. Levels of BTMs, adipokines, inflammatory factors, and gastrointestinal hormones could be affected by SG in obese rats. Serum PTP1B level might be associated with abnormal bone mass in obese rats.