Characterising body composition and bone health in transgender individuals receiving gender-affirming hormone therapy

Sex- and Gender-Related Differences in Obesity: From Pathophysiological Mechanisms to Clinical Implications

Obesity, primarily characterized by excessive fat accumulation, is a multifactorial chronic disease with an increasing global prevalence. Despite the well-documented epidemiology and significant advances in understanding its pathophysiology and clinical implications, the impact of sex is typically overlooked in obesity research. Worldwide, women have a higher likelihood to become obese compared to men. Although women are offered weight loss interventions more often and at earlier stages than men, they are more vulnerable to psychopathology. Men, on the other hand, are less likely to pursue weight loss intervention and are more susceptible to the metabolic implications of obesity. In this narrative review, we comprehensively explored sex- and gender-specific differences in the development of obesity, focusing on a variety of biological variables, such as body composition, fat distribution and energy partitioning, the impact of sex steroid hormones and gut microbiota diversity, chromosomal and genetic variables, and behavioural and sociocultural variables influencing obesity development in men and women. Sex differences in obesity-related comorbidities and varying effectiveness of different weight loss interventions are also extensively discussed.

Body Composition and Metabolic Syndrome Components in Transgender/Gender Diverse Adolescents and Young Adults

Purpose: The objective of this study was to examine the association of designated sex at birth, body composition, and gender-affirming hormone treatment (GAHT) with the components of metabolic syndrome (MetS) (overweight/obesity, elevated blood pressure [BP], altered glucose metabolism, and dyslipidemia) in transgender/gender diverse (TGD) adolescents and young adults. Methods: TGD individuals underwent body composition studies by bioelectrical impedance analysis according to designated sex at birth, and their muscle-to-fat ratio (MFR) z-scores were calculated. Generalized estimating equations with binary logistic models (n = 326) were used to explore associations while adjusting for potential confounders. Results: A total of 55 TGD females and 111 TGD males, with mean age of 18 ± 1.9 years and median duration of GAHT of 1.4 years (interquartile range = 0.6-2.5), were enrolled. Overall, 118/166 (71%) of the TGD cohort showed evidence of at least one MetS component, with a significantly higher rate among TGD males compared with TGD females (91.1% vs. 50.9%, p < 0.001). TGD males were at increased odds for overweight/obesity, elevated/hypertensive BP, elevated triglycerides (TGs), and an atherogenic dyslipidemia index (TG/high-density lipoprotein cholesterol [HDL-c], TG:HDL-c). The odds of overweight/obesity increased by 44.9 for each standard deviation decrease in the MFR z-score, while the odds for an elevated TG:HDL-c index increased by 3.7. Psychiatric morbidity increased the odds for overweight/obesity by 2.89. Conclusions: After considering confounding variables, the TGD males on GAHT were found to be at an increased risk for cardiometabolic disease. Our observations support the importance of targeted medical nutrition intervention in this group of individuals.

Body composition and risk for sarcopenia in transgender women

OBJECTIVES

Body composition and strength of cisgender (cis) individuals are well established. However, those for transgender women (trans women) undergoing gender-affirming hormone therapy remain unclear. This study aimed to detect possible body composition and strength variations related to sarcopenia.

METHODS

This was a cross-sectional comparative study of 37 trans women, 34 cis men, and 34 cis women. Body composition was measured in all individuals by bioelectrical impedance analysis; prehensile strength by dynamometry was studied in trans women.

RESULTS

In this study, trans women had higher body mass index values than cis individuals (P < 0.01). Fat mass was 41% higher for trans women than cis men. Muscle mass (MM) was lower in trans women than cis men (-10%), and higher than cis women (24%). Bone mass was lower in trans women than cis men and higher in cis women (P < 0.01). Trans women's prehensile strengths were 25.26 kg for the right hand and 24.8 kg for the left. Appendicular skeletal muscle mass was 23.63 kg, and appendicular skeletal muscle mass index was 8.14 kg.

CONCLUSION

Trans women undergoing gender-affirming hormone therapy show a tendency to adapt body compartments to those of cis women with increased fat mass and reduced muscle mass. Prehensile strength in trans women was close to the cutoff points for sarcopenia risk. Nutrition, physical activity, strength, and body composition are important to avoid the possible risk for sarcopenia. More studies along these lines are necessary, especially in older adults.

Effects of gender-affirming hormone therapy on body fat: a retrospective case‒control study in Chinese transwomen

BACKGROUND

There is insufficient research on how gender-affirming hormone therapy (GAHT) affects body fat modifications in transwomen from China. It is unclear whether hormone therapy affects the prevalence of obesity and blood lipid levels within this population. The current research aimed to assess how GAHT and treatment duration had an impact on the change in and redistribution of body fat in Chinese transwomen.

METHODS

This study included 40 transwomen who had not received GAHT and 59 who had. Body fat, blood lipid, and blood glucose levels were measured. GAHT is mainly a pharmacologic (estrogen and anti-androgen) treatment. The study also stratified participants based on the duration of GAHT to assess its impact on body fat distribution. The duration of GAHT was within one year, one to two years, two to three years, or more than three years.

RESULTS

After receiving GAHT, total body fat increased by 19.65%, and the percentage of body fat increased by 17.63%. The arm, corrected leg, and leg regions showed significant increases in fat content (+ 24.02%, + 50.69%, and + 41.47%, respectively) and percentage (+ 25.19%, + 34.90%, and + 30.39%, respectively). The total visceral fat content decreased (-37.49%). Based on the diagnostic standards for a body mass index ≥ 28 or total body fat percentage ≥ 25% or 30%, the chance of developing obesity did not change significantly. Blood glucose levels significantly increased (+ 12.31%). Total cholesterol levels (-10.45%) decreased significantly. Fat changes in those who received GAHT for one to two years were significantly different from those who did not receive GAHT.

CONCLUSION

After receiving GAHT, total body fat and regional fat increased in Chinese transwomen, and the body fat distribution changed from masculine to feminine, especially during the first two years. However, neither the increase in total body fat percentage nor the decrease in visceral fat content didn't bring about significant changes in the incidence of obesity, nor did triglycerides or low-density lipoprotein-cholesterol.

Unraveling sex-specific risks of knee osteoarthritis before menopause: Do sex differences start early in life?

OBJECTIVE

Sufficient evidence within the past two decades have shown that osteoarthritis (OA) has a sex-specific component. However, efforts to reveal the biological causes of this disparity have emerged more gradually. In this narrative review, we discuss anatomical differences within the knee, incidence of injuries in youth sports, and metabolic factors that present early in life (childhood and early adulthood) that can contribute to a higher risk of OA in females.

DESIGN

We compiled clinical data from multiple tissues within the knee joint-since OA is a whole joint disorder-aiming to reveal relevant factors behind the sex differences from different perspectives.

RESULTS

The data gathered in this review indicate that sex differences in articular cartilage, meniscus, and anterior cruciate ligament are detected as early as childhood and are not only explained by sex hormones. Aiming to unveil the biological causes of the uneven sex-specific risks for knee OA, we review the current knowledge of sex differences mostly in young, but also including old populations, from the perspective of (i) human anatomy in both healthy and pathological conditions, (ii) physical activity and response to injury, and (iii) metabolic signatures.

CONCLUSIONS

We propose that to close the gap in health disparities, and specifically regarding OA, we should address sex-specific anatomic, biologic, and metabolic factors at early stages in life, as a way to prevent the higher severity and incidence of OA in women later in life.

Abdominal CT metrics in 17,646 patients reveal associations between myopenia, myosteatosis, and medical phenotypes: a phenome-wide association study

BACKGROUND

Deep learning facilitates large-scale automated imaging evaluation of body composition. However, associations of body composition biomarkers with medical phenotypes have been underexplored. Phenome-wide association study (PheWAS) techniques search for medical phenotypes associated with biomarkers. A PheWAS integrating large-scale analysis of imaging biomarkers and electronic health record (EHR) data could discover previously unreported associations and validate expected associations. Here we use PheWAS methodology to determine the association of abdominal CT-based skeletal muscle metrics with medical phenotypes in a large North American cohort.

METHODS

An automated deep learning pipeline was used to measure skeletal muscle index (SMI; biomarker of myopenia) and skeletal muscle density (SMD; biomarker of myosteatosis) from abdominal CT scans of adults between 2012 and 2018. A PheWAS was performed with logistic regression using patient sex and age as covariates to assess for associations between CT-derived muscle metrics and 611 common EHR-derived medical phenotypes. PheWAS P values were considered significant at a Bonferroni corrected threshold (α = 0.05/1222).

FINDINGS

17,646 adults (mean age, 56 years ± 19 [SD]; 57.5% women) were included. CT-derived SMI was significantly associated with 268 medical phenotypes; SMD with 340 medical phenotypes. Previously unreported associations with the highest magnitude of significance included higher SMI with decreased cardiac dysrhythmias (OR [95% CI], 0.59 [0.55-0.64]; P < 0.0001), decreased epilepsy (OR, 0.59 [0.50-0.70]; P < 0.0001), and increased elevated prostate-specific antigen (OR, 1.84 [1.47-2.31]; P < 0.0001), and higher SMD with decreased decubitus ulcers (OR, 0.36 [0.31-0.42]; P < 0.0001), sleep disorders (OR, 0.39 [0.32-0.47]; P < 0.0001), and osteomyelitis (OR, 0.43 [0.36-0.52]; P < 0.0001).

INTERPRETATION

PheWAS methodology reveals previously unreported associations between CT-derived biomarkers of myopenia and myosteatosis and EHR medical phenotypes. The high-throughput PheWAS technique applied on a population scale can generate research hypotheses related to myopenia and myosteatosis and can be adapted to research possible associations of other imaging biomarkers with hundreds of EHR medical phenotypes.

FUNDING

National Institutes of Health, Stanford AIMI-HAI pilot grant, Stanford Precision Health and Integrated Diagnostics, Stanford Cardiovascular Institute, Stanford Center for Digital Health, and Stanford Knight-Hennessy Scholars.

Clinical and sociodemographic characteristics as predictors for quality of life in transmasculine and transfeminine individuals receiving gender-affirming hormone therapy

Healthcare systems and providers have increasingly acknowledged the role and impact of social determinants in overall health. However, gender-diverse individuals face persistent health disparities due to their identities. There is limited research on the impact of clinical and sociodemographic characteristics on mood and quality of life (QoL) for transgender (TG) individuals. Our study aims to understand and better elucidate social and clinical characteristics of transmasculine (TM) and transfeminine (TF) individuals and their impact on quality of life and depressive symptoms. In this cross-sectional study, 298 TF and TM individuals on gender-affirming hormone therapy (GAHT) were surveyed about their demographic characteristics (age, gender identity, body mass index (BMI), and education), social needs, mood, and quality of life. Multivariable regression modelling was performed to assess the effect of each variable listed above on three domains of QoL (psychological, environmental, and physical) as well as depressive symptoms. We find that QoL scores are similar between TM and TF individuals, with scores in the psychological domain particularly low in both cohorts. TM individuals report higher rates of stress and restroom avoidance than TF individuals. In particular, psychological well-being (measured by the psychological domain of QoL and depressive symptoms) is significantly associated with increased BMI, financial instability, and stress in TM individuals while for TF individuals, psychological well-being is associated with stress and social integration. These data suggest that social circumstances are key drivers of QoL and psychological well-being among gender-diverse individuals receiving GAHT with specific differences between TF and TM individuals. This information may be utilized by healthcare providers and policymakers to address and improve clinical care and social policies to improve health equity for gender-diverse individuals.

Bone health and body composition in transgender adults before gender-affirming hormonal therapy: data from the COMET study

PURPOSE

Preliminary data suggested that bone mineral density (BMD) in transgender adults before initiating gender-affirming hormone therapy (GAHT) is lower when compared to cisgender controls. In this study, we analyzed bone metabolism in a sample of transgender adults before GAHT, and its possible correlation with biochemical profile, body composition and lifestyle habits (i.e., tobacco smoke and physical activity).

METHODS

Medical data, smoking habits, phospho-calcic and hormonal blood tests and densitometric parameters were collected in a sample of 125 transgender adults, 78 Assigned Females At Birth (AFAB) and 47 Assigned Males At Birth (AMAB) before GAHT initiation and 146 cisgender controls (57 females and 89 males) matched by sex assigned at birth and age. 55 transgender and 46 cisgender controls also underwent a complete body composition evaluation and assessment of physical activity using the International Physical Activity Questionnaire (IPAQ).

RESULTS

14.3% of transgender and 6.2% of cisgender sample, respectively, had z-score values < -2 (p = 0.04). We observed only lower vitamin D values in transgender sample regarding biochemical/hormonal profile. AFAB transgender people had more total fat mass, while AMAB transgender individuals had reduced total lean mass as compared to cisgender people (53.94 ± 7.74 vs 58.38 ± 6.91, p < 0.05). AFAB transgender adults were more likely to be active smokers and tend to spend more time indoor. Fat Mass Index (FMI) was correlated with lumbar and femur BMD both in transgender individuals, while no correlations were found between lean mass parameters and BMD in AMAB transgender people.

CONCLUSIONS

Body composition and lifestyle factors could contribute to low BMD in transgender adults before GAHT.

Impact of continuous testosterone exposure on reproductive physiology, activity, and pain-related behavior in young adult female rats

Testosterone may reduce pain in cisgender women and transgender men. Rodents can provide a useful model for investigating physiological effects of hormone therapy. To this end, continuous-release testosterone or blank (placebo) capsules were implanted s.c. into young adult female rats, and three weeks later rats were either ovariectomized or sham-ovariectomized. Testosterone treatment that mimicked previously reported endogenous levels in males eliminated estrous cycling and decreased uterine weight. Testosterone also significantly increased body weight and suppressed the increases in daily wheel running observed in placebo controls over time. Subsequent ovariectomy or sham-ovariectomy decreased wheel running in all groups, but testosterone-treated rats recovered significantly more quickly than did placebo-treated rats. Neither testosterone nor ovariectomy significantly altered hindpaw mechanical threshold. Two weeks after sham/ovariectomy surgery, injection of Complete Freund Adjuvant (CFA) into one hindpaw reduced wheel running and mechanical threshold in all groups; running significantly decreased from the first to second day after CFA in testosterone- but not in placebo-treated rats. Morphine 1.0 but not 3.2 mg/kg increased CFA-suppressed wheel running similarly in all groups, whereas both doses of morphine increased CFA-suppressed mechanical threshold. These data suggest that weeks-long testosterone treatment with or without ovariectomy may provide a useful physiological model of testosterone therapy as used in human gender transition. Although testosterone administered at levels similar to those in gonadally intact males tended to hasten female rats' recovery from surgery, it did not decrease maximal pain-related behaviors after surgery or hindpaw inflammatory insult, nor did it alter opioid antinociception.

Sublingual Estradiol Offers No Apparent Advantage Over Combined Oral Estradiol and Cyproterone Acetate for Gender-Affirming Hormone Therapy of Treatment-Naive Trans Women: Results of a Prospective Pilot Study

Purpose

Chronic gender-affirming hormone therapy (GAHT) with sublingual estradiol (SLE) has not been studied. We aimed to compare GAHT with SLE only, to combined oral (CO) estradiol and cyproterone acetate, in treatment-naive trans women.

Methods

Twenty-two trans women enrolled into either the CO arm or the SLE-only arm (0.5 mg four times daily) in this 6-month prospective study. Anthropometric and laboratory variables were collected at baseline and 3 and 6 months. At the study beginning and end, body composition was measured by dual-energy X-ray absorptiometry and bioelectrical impedance, and gender dysphoria, sexual desire, and function were assessed by validated questionnaires.

Results

Subjects in the SLE were older, 26.3±5.8 years versus 20.1±2.3 years, p=0.006. All anthropometric, body composition, and laboratory variables were identical at baseline. Although dysphoria appeared greater, and sexual function lower at baseline in the CO group, this canceled out after age adjustment. Both treatments induced similar biochemical and hormonal changes. Creatinine, hemoglobin and cholesterol decreased significantly, while testosterone was suppressed to the same level in both groups: 3.22 [1.47-5.0] nmol/L in the SLE group and 2.41 [0.55-8.5] nmol/L in the CO, p=0.65. Significant changes in body composition toward a more feminine body were noted in both groups. Dysphoria did not significantly improve in either group, while sexual desire and function decreased at six months in both, p<0.001.

Conclusions

Both treatments achieved similar clinical changes. At this stage, SLE, which repeatedly induces alarming excursions of serum estradiol throughout the day, appears to offer no advantage over the CO approach.

Bone Health in the Transgender Population

» Transgender women are more susceptible to low bone mineral density (BMD) before initiating gender-affirming hormone therapy (GAHT), and while bone density initially improves with GAHT, it gradually declines while still remaining above baseline. Transgender women older than 50 years have a comparable fracture risk as age-matched cisgender women. Transgender men typically have normal or increased BMD before initiating and while receiving GAHT and are not at increased risk of fractures.» Transgender youth who receive puberty-blocking medications experience either no change or a slight decrease in BMD that returns to baseline after initiating GAHT.» It is important to abide by the International Society for Clinical Densitometry guidelines whenever ordering, performing, or reading a BMD scan for a gender-diverse patient.» There are no specific guidelines concerning vitamin D and calcium supplementation or the use of bisphosphonates in the transgender population, so the current recommendation is to abide by the guidelines for cisgender individuals.