Effect of bariatric surgery on endogenous sex hormones and sex hormone-binding globulin levels: a systematic review and meta-analysis

Metabolic outcomes in obese mice undergoing one-anastomosis gastric bypass (OAGB) with a long or a short biliopancreatic limb

One-anastomosis gastric bypass (OAGB) has gained importance as a simple, safe, and effective operation to treat morbid obesity. We previously found that Roux-en-Y gastric bypass surgery with a long compared with a short biliopancreatic limb (BPL) leads to improved weight loss and glucose tolerance in obese mice. However, it is not known whether a long BPL in OAGB surgery also results in beneficial metabolic outcomes. Five-week-old male C57BL/6J mice fed a high-fat diet (HFD) for 8 weeks underwent OAGB surgery with defined BPL lengths (5.5 cm distally of the duodenojejunal junction for short and 9.5 cm for long BPL), or sham surgery combined with caloric restriction. Weight loss, glucose tolerance, obesity-related comorbidities, endocrine effects, gut microbiota, and bile acids were assessed. Total weight loss was independent of the length of the BPL after OAGB surgery. However, a long BPL was associated with lower glucose-stimulated insulin on day 14, and an improved glucose tolerance on day 35 after surgery. Moreover, a long BPL resulted in reduced total cholesterol, while there were no differences in the resolution of metabolic dysfunction-associated steatotic liver disease (MASLD) and adipose tissue inflammation. Tendencies of an attenuated hypothalamic-pituitary-adrenal (HPA) axis and aldosterone were present in the long BPL group. With both the short and long BPL, we found an increase in primary conjugated bile acids (pronounced in long BPL) along with a loss in bacterial Desulfovibrionaceae and Erysipelotrichaceae and simultaneous increase in Akkermansiaceae, Sutterellaceae, and Enterobacteriaceae. In summary, OAGB surgery with a long compared with a short BPL led to similar weight loss, but improved glucose metabolism, lipid, and endocrine outcomes in obese mice, potentially mediated through changes in gut microbiota and related bile acids. Tailoring the BPL length in humans might help to optimize metabolic outcomes after bariatric surgery.NEW & NOTEWORTHY Weight loss following OAGB surgery in obese mice was not influenced by BPL length, but a longer BPL was associated with improved metabolic outcomes, including glucose and lipid homeostasis. These changes could be mediated by bile acids upon altered gut microbiota. Further validation of these findings is required through a randomized human study.

Hypogonadism and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), recently proposed to be renamed to metabolic dysfunction-associated steatotic liver disease (MASLD), is a major global public health concern, affecting approximately 25-30% of the adult population and possibly leading to cirrhosis, hepatocellular carcinoma, and liver transplantation. The liver is involved in the actions of sex steroids via their hepatic metabolism and production of the sex hormone-binding globulin (SHBG). Liver disease, including NAFLD, is associated with reproductive dysfunction in men and women, and the prevalence of NAFLD in patients with hypogonadism is considerable. A wide spectrum of possible pathophysiological mechanisms linking NAFLD and male/female hypogonadism has been investigated. As therapies targeting NAFLD may impact hypogonadism in men and women, and vice versa, treatments of the latter may affect NAFLD, and an insight into their pathophysiological pathways is imperative. This paper aims to elucidate the complex association between NAFLD and hypogonadism in men and women and discuss the therapeutic options and their impact on both conditions.

Effects of bariatric surgery on sexual function and fertility: A narrative review

Obesity has emerged as a prevalent global health concern, with its detrimental effects on the reproductive system and sexual function garnering increasing attention. Both men and women affected by obesity face a heightened risk of fertility challenges and sexual dysfunction. Although fertility and sexual function are distinct topics, they are intricately linked and mutually influential in both medical and societal contexts. Bariatric surgery (BS) has generated promising results in alleviating sexual dysfunction and enhancing fertility, results which are often gender specific. In men, improvements in sexual function can often be attributed to weight loss and subsequent optimizations in sex hormone levels. However, improving female sexual function may be related to a range of factors beyond weight loss. Bariatric procedures have shown limited benefits for male fertility; in fact, in some situations it can even be detrimental, leading to a decrease in sperm count and quality. Conversely, BS may positively impact female fertility, improving pregnancy and neonatal outcomes. Nevertheless, it is essential to consider the potential risks related to the adverse effects of malnutrition and rapid weight loss following BS, making it advisable to wait for 12-18 months before attempting pregnancy.

Plasma SHBG Levels as an Early Predictor of Response to Bariatric Surgery

BACKGROUND

Obesity is a growing global health problem, and currently, bariatric surgery (BS) is the best solution in terms of sustained total weight loss (TWL). However, a significant number of patients present weight regain (WR) in time. There is a lack of biomarkers predicting the response to BS and WR during the follow-up. Plasma SHBG levels, which are low in obesity, increase 1 month after BS but there is no data of plasma SHBG levels at long term. We performed the present study aimed at exploring the SHBG role in predicting TWL and WR after BS.

METHODS

Prospective study including 62 patients with obesity undergoing BS. Anthropometric and biochemical variables, including SHBG were analyzed at baseline, 1, 6, 12, and 24 months; TWL ≥ 25% was considered as good BS response.

RESULTS

Weight loss nadir was achieved at 12 months post-BS where maximum SHBG increase was reached. Greater than or equal to 25% TWL patients presented significantly higher SHBG increases at the first and sixth months of follow-up with respect to baseline (100% and 150% respectively, p = 0.025), than < 25% TWL patients (40% and 50% respectively, p = 0.03). Also, these presented 6.6% WR after 24 months. The first month SHBG increase predicted BS response at 24 months (OR = 2.71; 95%CI = [1.11-6.60]; p = 0.028) and TWL in the 12th month (r = 0.330, p = 0.012) and the WR in the 24th (r =  - 0.301, p = 0.028).

CONCLUSIONS

Our results showed for the first time that increase in plasma SHBG levels within the first month after BS is a good predictor of TWL and WR response after 2 years.

Bariatric Surgery in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine condition in premenopausal women and is a common cause of anovulatory subfertility. Although obesity does not form part of the diagnostic criteria, it affects a significant proportion of women with PCOS and is strongly implicated in the pathophysiology of the disease. Both PCOS and obesity are known to impact fertility in women; obesity also reduces the success of assisted reproductive technology (ART). With or without pharmacotherapy, lifestyle intervention remains the first-line treatment in women with PCOS and obesity. Bariatric surgery is still an experimental treatment in women with PCOS and subfertility. This review will present an overview of the pathophysiology of PCOS and obesity and the role of bariatric surgery. Although data are sparse regarding the impact of bariatric surgery on subfertility in women with PCOS and obesity, existing studies point to a beneficial role in treating metabolic and reproductive dysfunction.

Improved Insulin Secretion Response and Beta-cell Function Correlated with Increased Prolactin Levels After Laparoscopic Sleeve Gastrectomy in Morbidly Obese Patients with Acanthosis Nigricans

OBJECTIVE

To explore insulin secretion patterns, β-cell function, and serum prolactin (PRL) concentrations in Chinese morbidly obese patients with Acanthosis nigricans (AN) and their alterations after laparoscopic sleeve gastrectomy (LSG).

METHODS

A total of 138 morbidly obese subjects undergoing LSG were categorized as simple obesity without AN (OB group, n = 55) and obesity with AN (AN group, n = 83). Oral glucose tolerance test (OGTT), PRL, and related metabolic indices were performed pre- and 12 months post-LSG. Insulin secretion patterns were derived from insulin secretion peak time during OGTT: type I (peak at 30 or 60 min) and type II (peak at 120 or 180 min).

RESULTS

Preoperatively, AN group showed significantly higher proportions of type II insulin secretion pattern, fasting insulin (FINS), and homeostatic model assessment of insulin resistance (HOMA-IR) whereas lower oral glucose insulin sensitivity (OGIS), insulinogenic index (IGI), and disposition index (DI) than OB group, which were improved significantly at 12 months postoperatively in both groups, more pronounced in AN group. Intriguingly, serum PRL declined substantially in AN group than OB group at baseline whereas elevated only in the AN group post-LSG. After adjusting for confounding factors, elevated PRL correlated significantly with increased IGI and DI, and decreased HOMA-IR in both genders, as well as increased OGIS in females, which was detected only in the AN group CONCLUSION: Morbidly obese patients with AN presented delayed insulin secretion response, impaired insulin secretion, and β-cell dysfunction, which were significantly improved by LSG and might benefit from elevated PRL.

Evaluation of bone density and skeletal muscle mass after sleeve gastrectomy using computed tomography method

Introduction

Sleeve gastrectomy is the most common surgical procedure to reduce weight and treat metabolic complications in patients with moderate-to-severe obesity; however, it affects the musculoskeletal system. Dual-energy X-ray absorptiometry (DXA), which is commonly used to measure bone mineral density (BMD), may be affected by excess fat tissue around the bones, interrupting BMD measurement. Due to the strong correlation between DXA and the Hounsfield units (HU) obtained from computed tomography (CT) scans, BMD assessment using clinical abdominal CT scans has been useful. To date, there has been no report of detailed CT evaluation in patients with severe obesity after sleeve gastrectomy.

Objective

This study investigated the effect of sleeve gastrectomy in severely obese patients on bone and psoas muscle density, and cross-sectional area using retrospective clinical CT scans.

Methods

This was a retrospective observational study that included 86 patients (35 males and 51 females) who underwent sleeve gastrectomy between March 2012 and May 2019. Patients' clinical data (age at the time of surgery, sex, body weight, body mass index (BMI), comorbidities, and preoperative and postoperative blood test results, HU of the lumbar spine and psoas muscle and psoas muscle mass index (PMI)) were evaluated.

Results

The mean age at the time of surgery was 43 years, and the body weight and BMI significantly reduced (p < 0.01) after surgery. The mean hemoglobin A1c level showed significant improvement in males and females. Serum calcium and phosphorus levels remained unchanged before and after surgery. In CT analysis, HU of the lumbar spine and psoas muscle showed no significant decrease, but PMI showed a significant decrease (p < 0.01).

Conclusions

Sleeve gastrectomy could dramatically improve anthropometric measures without causing changes in serum calcium and phosphorus levels. Preoperative and postoperative abdominal CT revealed no significant difference in the bone and psoas muscle density, and the psoas muscle mass was significantly decreased after sleeve gastrectomy.

Effect of bariatric surgery on carotid intima-media thickness: A meta-analysis based on observational studies

Objective

This meta-analysis aimed to investigate the effect of bariatric surgery on CIMT in people with obesity.

Methods

PubMed, Web of Science, Embase, and the Cochrane Library were searched for observational studies assessing the effect of bariatric surgery on CIMT from inception to August 2022. Mean difference (MD) and 95% confidence intervals were calculated to assess CIMT.

Results

A total of 23 studies, including 1,349 participants, were eligible to participate in this meta-analysis. The results revealed that CIMT was significantly decreased at 6 months, 12 months, and more than 18 months after bariatric surgery compared with baseline (6 months: MD = 0.09; P < 0.01; 12 months: MD = 0.12; P < 0.01; more than 18 months: MD = 0.14; P = 0.02). Meanwhile, laparoscopic Roux-en-Y gastric bypass (LRYGB) seemed to be more effective than laparoscopic sleeve gastrectomy (LSG) in lowering CIMT in terms of the type of surgery (LSG: MD = 0.11; P < 0.01; LRYGB: MD = 0.14; P < 0.01). Lastly, the benefits of bariatric surgery on CIMT was independent of gender (Male: MD = 0.06; P = 0.04; Female: MD = 0.08; P = 0.03).

Conclusions

Bariatric surgery is consistently effective in reducing CIMT in people with obesity.

Obesity, type 2 diabetes, and testosterone in ageing men

In the absence of obesity, adverse lifestyle behaviours, and use of medication such as opioids serum testosterone concentrations decrease by only a minimal amount at least until very advanced age in most men. Obesity is heterogeneous in its phenotype, and it is the accumulation of excess adipose tissue viscerally associated with insulin resistance, dyslipidaemia, inflammation, hypothalamic leptin resistance and gliosis that underpins the functional hypogonadism of obesity. Both central (hypothalamic) and peripheral mechanisms are involved resulting in a low serum total testosterone concentration, while LH and FSH are typically in the normal range. Peripherally a decrease in serum sex hormone binding globulin (SHBG) concentration only partially explains the decrease in testosterone and there is increasing evidence for direct effects in the testis. Men with obesity associated functional hypogonadism and serum testosterone concentrations below 16 nmol/L are at increased risk of incident type 2 diabetes (T2D); high testosterone concentrations are protective. The magnitude of weight loss is linearly associated with an increase in serum testosterone concentration and with the likelihood of preventing T2D or reverting newly diagnosed disease; treatment with testosterone for 2 years increases the probability of a positive outcome from a lifestyle intervention alone by approximately 40%. Whether the additional favourable benefits of testosterone treatment on muscle mass and strength and bone density and quality in the long-term remains to be determined.

Sex-specific differences in bone mineral density loss after sleeve gastrectomy

Background

Sleeve gastrectomy is an effective bariatric procedure; however, sleeve gastrectomy-related adverse skeletal outcomes have been increasingly reported. High levels of sex hormone-binding globulin (SHBG) have been documented to be a risk factor of bone mineral density (BMD) loss with different effects observed between sexes. The aim of this study was to identify sex-specific changes in BMD following sleeve gastrectomy and to evaluate the role of SHBG in this process.

Methods

This retrospective study included 19 middle-aged men and 30 non-menopausal women with obesity who underwent sleeve gastrectomy in China. Anthropometrics, bone turnover markers, calciotropic hormones, BMD, SHBG, and gonadal steroids were measured preoperatively and at 6 and 12 months postoperatively. Longitudinal changes in BMD, bone turnover markers and SHBG were compared between sexes by linear mixed models. Multiple stepwise regression analysis was used to identify the predictors of BMD loss at the investigated bone sites.

Results

Over the 12-month study period, total hip and femoral neck BMD decreased, while lumbar spine BMD remained largely unchanged in both sexes. Linear mixed models revealed significant sex × time interaction effects in total hip BMD and SHBG, showing that men had a significantly greater reduction in total hip BMD and less increase in SHBG after sleeve gastrectomy than women. In the multivariate model, SHBG was significantly associated with total hip BMD loss in men (adjusted β = −0.533, P = 0.019) but not women while total estrogen was significantly associated with total hip BMD loss in women (adjusted β = 0.508, P = 0.01) but not men.

Conclusion

Significant sex-specific BMD changes were observed after sleeve gastrectomy in the current study. Sleeve gastrectomy-related increase in SHBG may be a specific risk factor for total hip BMD loss in men. Our results indicate that sex-specific screening may be warranted to facilitate personalized postoperative bone care in this population.

Might female patients benefit more from bariatric surgery with respect to inflammation

Background

Bariatric surgery is an effective method for severe obesity and its related comorbidities, in which inflammation plays a crucial role. The aim of this study was to investigate the changes of Neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein (CRP) in patients undergoing laparoscopic sleeve gastrectomy (LSG) and to explore the related factors including gender.

Methods

We retrospectively included 72 patients undergoing LSG in our hospital from 2017 to 2020. Clinical information, laboratory investigations as well as parameters derived from traditional and 2D strain echocardiography were collected. Univariate logistic model was used in myocardial performance index (MPI) and E/E′ analysis. Univariate and Multivariate logistic model were used in NLR analysis.

Results

At baseline, all patients had normal left ventricular ejection fraction (LVEF). The myocardial performance index (MPI) (OR = 1.218 (95%CI 1.040, 1.426); p = 0.0142) and E/E′ (OR = 1.364 (95%CI 1.124, 1.655); p = 0.0017) were independently associated with CRP. LSG led to a significant decrease in inflammatory markers (NLR, 2.4 ± 1.59 vs.1.7 ± 0.86; CRP, 5.6 ± 3.17 vs. 2.1 ± 2.35 mg/L, respectively, both p < 0.001),which was more in NLR among female than male (OR = 3.14 (95%CI 1.112, 8.870); p = 0.031).

Conclusions

The present study indicated a significant correlation between subclinical cardiac dysfunction and CRP among obese patients. Furthermore, female patients might benefit more from bariatric surgery on inflammation.

Genetic Associations of Birthweight, Childhood, and Adult BMI on Testosterone Levels: A Mendelian Randomization

CONTEXT

Birthweight, childhood, and adult BMI have been indicated associated with the testosterone levels, but the current studies are plagued by significant heterogeneity, and a consensus about the role of these weight traits in testosterone levels is still debated.

OBJECTIVE

This work aims to evaluate the genetic associations of birthweight and childhood and adult body mass index (BMI) on the adult testosterone levels (bioavailable testosterone [BT], sex hormone-binding globulin [SHBG], and total testosterone [TT]) in women and men.

METHODS

Random-effect inverse-variance weighted (IVW) and 7 sensitivity analyses were performed. Data for weight traits were collected from large-scale genome-wide association studies (GWAS) ranging from 39 620 to 434 794 individuals. Summarized data for testosterone levels were obtained from a GWAS up to 230 454 individuals.

RESULTS

Higher adult BMI are significantly associated with lower BT (β = -0.13; 95% CI, -0.16 to -0.09) and TT in men (β = -0.25; 95% CI, -0.30 to -0.20). On the contrary, higher adult BMI increased the levels of BT (β = 0.23; 95% CI, 0.23 to 0.20) and TT (β = 0.04; 95% CI, 0.01 to 0.07) in women. Similar genetic associations on testosterone levels with sexual differences were observed for childhood BMI. However, higher birthweight led to lower BT levels in adult men (β = -0.08; 95% CI, -0.12 to -0.03) and women (β = -0.07; 95% CI, -0.13 to -0.02).

CONCLUSION

Our study supports that birthweight, childhood BMI, and adult BMI affect testosterone levels in men and women in adult life. The genetic associations of childhood BMI on testosterone levels are consistent with adult BMI, but not with birthweight.

Associations of Sex Hormone-binding Globulin with Bone Mineral Density Among US Adults, NHANES 2013-2016

Background

Bone metabolism can be influenced by sex steroid hormones. However, the relationship between sex steroid hormones and bone mineral density (BMD) remains inconsistent. Our study explored existing evidence of the association between sex hormones, blood glucose and BMD.

Methods

We conducted a cross-sectional study of 6434 participants aged 18–80 years in the National Health and Nutrition Examination Survey (NHANES) 2013–2016 to assess the association between SHBG and BMD. The multivariable linear regression models were performed to evaluate the associations between testosterone, estrogen, sex hormone-binding globulin (SHBG) and BMD.

Results

On adjustment for traditional risk factors (age, BMI, ALB, ALK, ASP, calcium, cholesterol, potassium, sodium, total protein, uric acid), SHBG could be regarded as an independent predictor for BMD, while fasting blood glucose did not. SHBG levels were significant associated with BMD in the multivariate model; however, it will be a different effect between the genders. On comparative analysis, high level SHBG was predictive of lumbar BMD irrespective of other two sex steroid hormones.

Conclusion

This study indicated that SHBG may improve the predictive value for bone loss in adults.