Bone Parameters in Anorexia Nervosa and Athletic Amenorrhea: Comparison of Two Hypothalamic Amenorrhea States

Characteristics of bone mineral density in patients with functional hypothalamic amenorrhoea and its association with reproductive hormones and body composition

OBJECTIVE

Bone mineral density (BMD) is typically reduced in patients with female athlete triad (FAT) and anorexia nervosa (AN). However, bone health in most patients with functional hypothalamic amenorrhoea (FHA), who may not suffer from severe energy deficiency, has not received adequate attention in clinical practice. This study aimed to investigate BMD and its association with clinical and endocrine features in individuals with FHA and to provide clinical evidence for improving bone loss and preventing osteoporosis in FHA.

DESIGN

To assess the bone status of patients with FHA and investigate its association with various clinical and endocrinological characteristics.

PATIENTS

We retrospectively analysed 80 patients with FHA who attended the Obstetrics and Gynecology Hospital of Fudan University from January 2022 to March 2023.

MEASUREMENTS

The levels of reproductive hormones, including luteinising hormone (LH), follicle-stimulating hormone, oestradiol (E2 ) and total testosterone (TT), were examined at the time of initial diagnosis, and a body composition analyser was used to measure body fat percentage (BF%), lean body mass (LBM) and segmental muscle/fat. Dual-emission X-ray absorptiometry was used to measure lumbar spine BMD and femoral neck BMD in patients with FHA, and the Z score was calculated.

RESULTS

The study cohort consisted of 80 female patients with FHA. The average age of the patients was 24.64 ± 6.02 years, and their body mass index (BMI) was 19.47 ± 2.86 kg/m2 . The duration of weight loss was 12 (6, 24) months, while the duration of oligo/amenorrhoea was 12 (4.5, 24) months. The mean degree of weight loss was 18.39 ± 9.53%. Low BMD were present in 15% of patients with FHA at the lumbar spine and/or femoral neck; 12.5% and 10% had low bone mass at the lumbar spine and femoral neck, respectively. The low bone mass group experienced a longer period of weight loss than the normal group [24 (16.5, 60) vs. 12 (4.5, 24) months, p = .037]. In addition, the abnormal group had a lower BMR (basal metabolic rate, BMR) [1158 ± 85 vs. 1231 ± 91 kcal/day, p = .011] and lower bone mineral content [2.15 ± 0.26 vs. 2.43 ± 0.31 kg, p = .009] than the normal group. Both LBMD and femoral neck BMD (Fn BMD) were positively correlated with BMI, BF%, LBM, and regional muscle/fat mass (all p < .05). There was also a positive correlation between LBMD and basal LH levels (p = .009) and waist-to-hip ratio (p = .034), whereas Fn BMD was positively correlated with TT levels (p = .029). Multiple linear regression analysis showed that LBM was positively associated with LBMD (β = .007, 95% confidence interval [CI] = 0.004-0.009, p < .001), while trunk muscle mass was positively associated with Fn BMD (β = .046, 95% CI = 0.013-0.080, p = .008).

CONCLUSION

Fifteen percent of the patients with FHA exhibited low bone mass, a condition associated with prolonged weight loss. The basal LH and TT levels showed positive correlations with LBMD and Fn BMD, respectively. Meanwhile, BMR levels, BMI, BF%, and muscle mass were all positively correlated with LBMD and Fn BMD. Clinically, we should be attentive to suboptimal bone health in patients with FHA and take early screening, diagnosis and intervention measures, especially appropriate muscle mass gain, to prevent the onset of osteoporosis and fragility fractures in the long term.

Hypothalamic subregion alterations in anorexia nervosa and obesity: Association with appetite-regulating hormone levels

OBJECTIVE

Anorexia nervosa (AN) and obesity are weight-related disorders with imbalances in energy homeostasis that may be due to hormonal dysregulation. Given the importance of the hypothalamus in hormonal regulation, we aimed to identify morphometric alterations to hypothalamic subregions linked to these conditions and their connection to appetite-regulating hormones.

METHODS

Structural magnetic resonance imaging (MRI) was obtained from 78 patients with AN, 27 individuals with obesity and 100 normal-weight healthy controls. Leptin, ghrelin, and insulin blood levels were measured in a subsample of each group. An automated segmentation method was used to segment the hypothalamus and its subregions. Volumes of the hypothalamus and its subregions were compared between groups, and correlational analysis was employed to assess the relationship between morphometric measurements and appetite-regulating hormone levels.

RESULTS

While accounting for total brain volume, patients with AN displayed a smaller volume in the inferior-tubular subregion (ITS). Conversely, obesity was associated with a larger volume in the anterior-superior, ITS, posterior subregions (PS), and entire hypothalamus. There were no significant volumetric differences between AN subtypes. Leptin correlated positively with PS volume, whereas ghrelin correlated negatively with the whole hypothalamus volume in the entire cohort. However, appetite-regulating hormone levels did not mediate the effects of body mass index on volumetric measures.

CONCLUSION

Our results indicate the importance of regional structural hypothalamic alterations in AN and obesity, extending beyond global changes to brain volume. Furthermore, these alterations may be linked to changes in hormonal appetite regulation. However, given the small sample size in our correlation analysis, further analyses in a larger sample size are warranted.

PUBLIC SIGNIFICANCE

Using an automated segmentation method to investigate morphometric alterations of hypothalamic subregions in AN and obesity, this study provides valuable insights into the complex interplay between hypothalamic alterations, hormonal appetite regulation, and body weight, highlighting the need for further research to uncover underlying mechanisms.

Maximal Resistance Training in the Treatment of Anorexia Nervosa - A Case Report Series

Objective

Anorexia Nervosa (AN) has one of the highest mortality rates of all mental health disorders, low recovery rate and is associated with widespread endocrine dysfunction. Resistance training (RT) has been consistently shown to provide beneficial effects on health outcomes that are often negatively affected by AN, however participation in exercise is controversial for individuals with AN. The objective of this study was to assess the effects of maximal RT as an add-on to standard of care in patients with AN.

Methods

Originally, a controlled clinical trial was planned but due to COVID-19 pandemic, the study was prematurely ended and reported as a case series design. Three female inpatients with AN (Age 18-29 years, body mass index (BMI) 14.5-16.3 kg/m2, illness duration 1-7 years) underwent a supervised 6-week RT intervention as an add-on to standard of care. Primary outcome was muscular strength, as measured by a 1-repetition maximum. Secondary outcomes included BMI, eating disorder psychopathology and maladaptive exercise tendencies.

Results

No adverse events were reported. All three participants improved lower body muscle strength, ranging from 32% to 134% in the leg press. Changes of 4% to 134% in the bench press and -3% to 38% in the pulldown were also observed.

Conclusions

RT improved muscular strength in the participants. RT as part of standard of care may also provide additional benefits for individuals with AN, although further research is required to determine which subtype of patients would benefit from the addition of RT to their treatment protocol.

My 28 Days - a global digital women's health initiative for evaluation and management of secondary amenorrhea: case report and literature review

There is a need to close the gap between knowledge and action in health care. Effective care requires a convenient and reliable distribution process. As global internet and mobile communication increase capacity, innovative approaches to digital health education platforms and care delivery are feasible. We report the case of a young African woman who developed acute secondary amenorrhea at age 18. Subsequently, she experienced a 10-year delay in the diagnosis of the underlying cause. A global digital medical hub focused on women's health and secondary amenorrhea could reduce the chance of such mismanagement. Such a hub would establish more efficient information integration and exchange processes to better serve patients, family caregivers, health care providers, and investigators. Here, we show proof of concept for a global digital medical hub for women's health. First, we describe the physiological control systems that govern the normal menstrual cycle, and review the pathophysiology and management of secondary amenorrhea. The symptom may lead to broad and profound health implications for the patient and extended family members. In specific situations, there may be significant morbidity related to estradiol deficiency: (1) reduced bone mineral density, 2) cardiovascular disease, and 3) cognitive decline. Using primary ovarian insufficiency (POI) as the paradigm condition, the Mary Elizabeth Conover Foundation has been able to address the specific global educational needs of these women. The Foundation did this by creating a professionally managed Facebook group specifically for these women. POI most commonly presents with secondary amenorrhea. Here we demonstrate the feasibility of conducting a natural history study on secondary amenorrhea with international reach to be coordinated by a global digital medical hub. Such an approach takes full advantage of internet and mobile device communication systems. We refer to this global digital women's health initiative as My 28 Days®.

Medical and physiological complications of exercise for individuals with an eating disorder: A narrative review

Individuals with eating disorders (ED) experience prolonged malnutrition, binge episodes, and compensatory behaviours that affect every organ system. Psychological and physiological symptoms are worsened with comorbid dysfunctional exercise, seen in up to 80% of those with an ED. Although return to exercise is an important component of treatment and recovery, little is known about the contraindications and risks of exercise engagement specific to those with an ED. This paper provides a comprehensive narrative review of the medical and physiological complications of engaging in exercise during ED treatment and outlines when exercise may be contraindicated or used in modified or cautionary ways. We conducted a literature search on MEDLINE, PubMed, and PsychArticles to identify relevant articles, which yielded six categories of medical and physiological complications of ED that may be exacerbated by exercise: energy availability, cardiovascular health, electrolyte abnormalities, biomedical function markers, sex hormones, and body composition. We summarize the evidence for these complications for readers and offer an initial set of recommendations for incorporating exercise during ED treatment based on our findings. This review may serve as a resource for members of ED treatment teams to help evaluate more readily and confidently whether exercise is safe for individual patients and when modifications and caution may be warranted.

Association of Short-Term Changes in Menstrual Frequency, Medication Use, Weight and Exercise on Bone Mineral Density in College-Aged Women

To evaluate if experiencing a short-term exposure (18-months) to factors such as menstrual irregularities, dieting, changes in exercise or body weight, and medication usage is associated with bone mineral density (BMD) in college-aged females. A retrospective survey assessing health behaviors during a recent 18-month time period and a DXA scan were completed in 641 females. A total of 45.5% of participants reported amenorrhea during the 18-month time period. Those who experienced amenorrhea had lower femoral neck BMD (p = 0.018), trochanter (p = 0.018) and spine BMD (p = 0.022) compared to eumenorrheic women. Lifetime oral contraceptive usage longer than six months was negatively associated with BMD at femoral neck (p = 0.018) and total hip (p = 0.021). Women who lost weight trended towards having the lowest BMD at all sites compared to women who gained weight. Following a very-low calorie diet during the time period was negatively correlated with spine BMD (p = 0.001). Time spent in vigorous and very vigorous activity was weakly correlated with some hip BMD sites but time spent in extremely vigorous activity was not. In conclusion, females who experienced weight loss, amenorrhea, or a very low-calorie diet within an 18-month period of time in young adulthood had lower BMD. Additionally, oral contraceptive usage for longer than six months during their lifetime was associated with lower BMD.

Bone Perspectives in Functional Hypothalamic Amenorrhoea: An Update and Future Avenues

One of the most important and potentially long-lasting detrimental consequences of Functional Hypothalamic Amenorrhoea (FHA) is on skeletal homeostasis. Beyond oestrogen deficiency, FHA is associated with a cascade of additional neuro-endocrine and metabolic alterations, some adaptive, but which combine to disrupt skeletal homeostasis. Ultimately, this leads to a two-fold increased risk of fractures in women with FHA compared to healthy eumenorrhoeic women. Although the cornerstone of management of FHA-related bone loss remains recovery of menses via restoration of metabolic/psychological balance, there is rapidly developing evidence for hormonal manipulations (with a particular emphasis on route of administration) and other pharmacological treatments that can protect or improve skeletal homeostasis in FHA. In this mini-review, we provide an update on the pathophysiology, clinical management and future avenues in the field from a bone perspective.

The female athlete triad: review of current literature

PURPOSE OF REVIEW

Adolescence and young adulthood are a critical period in the life of women for optimizing long-term bone health. Young athletes lead a demanding lifestyle with increased dietary requirements to meet the robust demands of energy expenditure to maintain a state of energy balance. During a time of fast paced changes and unpredictable societal demands on young athletes, it is important to review the severe consequences of energy deficiency and options for adequate management.

RECENT FINDINGS

This review focuses on hormonal adaptations that occur in energy deficient female athletes that lead to menstrual irregularities and impaired bone health, increasing the risk for stress and other fractures. We also describe management strategies to mitigate the consequences of limited energy availability on bone and other outcomes.

SUMMARY

These strategies should help guide the management of young female athletes to prevent irreversible changes to their bone health. Identifying current knowledge should help increase awareness among medical providers, which can then be communicated to the sports community, parents, and athletes.

Functional hypothalamic amenorrhea: Impact on bone and neuropsychiatric outcomes

Functional hypothalamic amenorrhea is a state of reversible hypogonadism common in adolescents and young women that can be triggered by energy deficit or emotional stress or a combination of these factors. Energy deficit may be a consequence of (i) reduced caloric intake, as seen in patients with eating disorders, such as anorexia nervosa, or (ii) excessive exercise, when caloric intake is insufficient to meet the needs of energy expenditure. In these conditions of energy deficit, suppression of the hypothalamic secretion of gonadotrophin-releasing hormone (with resulting hypoestrogenism) as well as other changes in hypothalamic-pituitary function may occur as an adaptive response to limited energy availability. Many of these adaptive changes, however, are deleterious to reproductive, skeletal, and neuropsychiatric health. Particularly, normoestrogenemia is critical for normal bone accrual during adolescence, and hypoestrogenemia during this time may lead to deficits in peak bone mass acquisition with longstanding effects on skeletal health. The adolescent years are also a time of neurological changes that impact cognitive function, and anxiety and depression present more frequently during this time. Normal estrogen status is essential for optimal cognitive function (particularly verbal memory and executive function) and may impact emotion and mood. Early recognition of women at high risk of developing hypothalamic amenorrhea and its timely management with a multidisciplinary team are crucial to prevent the severe and long-term effects of this condition.

Bone health in functional hypothalamic amenorrhea: What the endocrinologist needs to know

In the original definition by Klinefelter, Albright and Griswold, the expression "hypothalamic hypoestrogenism" was used to describe functional hypothalamic amenorrhoea (FHA). Given the well-known effects of estrogens on bone, the physiopathology of skeletal fragility in this condition may appear self-explanatory. Actually, a growing body of evidence has clarified that estrogens are only part of the story. FHA occurs in eating disorders, overtraining, and during psychological or physical stress. Despite some specific characteristics which differentiate these conditions, relative energy deficiency is a common trigger that initiates the metabolic and endocrine derangements contributing to bone loss. Conversely, data on the impact of amenorrhoea on bone density or microarchitecture are controversial, and reduced bone mass is observed even in patients with preserved menstrual cycle. Consistently, oral estrogen-progestin combinations have not proven beneficial on bone density of amenorrheic women. Low bone density is a highly prevalent finding in these patients and entails an increased risk of stress or fragility fractures, and failure to achieve peak bone mass and target height in young girls. Pharmacological treatments have been studied, including androgens, insulin-like growth factor-1, bisphosphonates, denosumab, teriparatide, leptin, but none of them is currently approved for use in FHA. A timely screening for bone complications and a multidisciplinary, customized approach aiming to restore energy balance, ensure adequate protein, calcium and vitamin D intake, and reverse the detrimental metabolic-endocrine changes typical of this condition, should be the preferred approach until further studies are available.

Skeletal endocrinology: where evolutionary advantage meets disease

The regulation of whole-body homeostasis by the skeleton is mediated by its capacity to secrete endocrine signaling molecules. Although bone-derived hormones confer several adaptive benefits, their physiological functions also involve trade-offs, thus eventually contributing to disease. In this manuscript, we discuss the origins and functions of two of the best-studied skeletal mediators, fibroblast growth factor 23 and osteocalcin, in an evolutionary context. Moreover, we provide a theoretical framework seeking to explain the broad involvement of these two hormones in amniote physiology as well as their potential to fuel the development and progression of diseases. Vice versa, we outline which perturbations might be amenable to manipulation of these systems and discuss limitations and ongoing challenges in skeletal endocrine research. Finally, we summarize unresolved questions and potential future studies in this thriving field.

From Pharmacology to Physiology: Endocrine Functions of μ-Opioid Receptor Networks

The steady rise in opioid users and abusers has uncovered multiple detrimental health consequences of perturbed opioid receptor signaling, thereby creating the need to better understand the biology of these systems. Among endogenous opioid networks, μ-receptors have received special attention due to their unprecedented biological complexity and broad implications in homeostatic functions. Here, we review the origin, molecular biology, and physiology of endogenous opioids with a special focus on μ-opioid receptor networks within the endocrine system. Moreover, we summarize the current evidence supporting an involvement of the latter in regulating distinct endocrine functions. Finally, we combine these insights to present an integrated perspective on μ-opioid receptor biology and provide an outlook on future studies and unresolved questions in this field.

Risk Factors, Diagnosis and Management of Bone Stress Injuries in Adolescent Athletes: A Narrative Review

Physical activity is known to be beneficial for bone; however, some athletes who train intensely are at risk of bone stress injury (BSI). Incidence in adolescent athlete populations is between 3.9 and 19% with recurrence rates as high as 21%. Participation in physical training can be highly skeletally demanding, particularly during periods of rapid growth in adolescence, and when competition and training demands are heaviest. Sports involving running and jumping are associated with a higher incidence of BSI and some athletes appear to be more susceptible than others. Maintaining a very lean physique in aesthetic sports (gymnastics, figure skating and ballet) or a prolonged negative energy balance in extreme endurance events (long distance running and triathlon) may compound the risk of BSI with repetitive mechanical loading of bone, due to the additional negative effects of hormonal disturbances. The following review presents a summary of the epidemiology of BSI in the adolescent athlete, risk factors for BSI (physical and behavioural characteristics, energy balance and hormone disruption, growth velocity, sport-specific risk, training load, etc.), prevention and management strategies.

Growth Delay in Inflammatory Bowel Diseases: Significance, Causes, and Management

Growth delay with height and weight impairment is a common feature of pediatric inflammatory bowel diseases (PIBD). Up to 2/3 of Crohn Disease patients have impaired weight at diagnosis, and up to 1/3 have impaired height. Ulcerative colitis usually manifests earlier with less impaired growth, though patients can be affected. Ultimately, growth delay, if not corrected, can reduce final adult height. Weight loss, reduced bone mass, and pubertal delay are also concerns associated with growth delay in newly diagnosed PIBD patients. The mechanisms for growth delay in IBD are multifactorial and include reduced nutrient intake, poor absorption, increased fecal losses, as well as direct effects from inflammation and treatment modalities. Management of growth delay requires optimal disease control. Exclusive enteral nutrition (EEN), biologic therapy, and corticosteroids are the primary induction strategies used in PIBD, and both EEN and biologics positively impact growth and bone development. Beyond adequate disease control, growth delay and pubertal delay require a multidisciplinary approach, dependent on diligent monitoring and identification, nutritional rehabilitation, and involvement of endocrinology and psychiatry services as needed. Pitfalls that clinicians may encounter when managing growth delay include refeeding syndrome, obesity (even in the setting of malnutrition), and restrictive diets. Although treatment of PIBD has improved substantially in the last several decades with the era of biologic therapies and EEN, there is still much to be learned about growth delay in PIBD in order to improve outcomes.

Assessment of energy availability and associated risk factors in professional female soccer players

This study aimed to assess energy availability (EA), alongside possible risk factors of reduced or low EA of professional female soccer players during a competitive season. Thirteen players (age: 23.7 ± 3.4 y, stature: 1.69 ± 0.08 m, body mass: 63.7 ± 7.0 kg) engaged in a 5-day (two rest days, one light training, heavy training and match day) monitoring period. Energy intake (EI) and expenditure during exercise (EEE) were measured. EA was calculated and categorised as optimal, reduced or low (>45, 30-45, <30 kcal·kg FFM^-1·day^-1, respectively). Relationships between EA and bone mineral density, resting metabolic rate (RMR), plasma micronutrient status, biochemical markers and survey data were assessed. EA was optimal for 15%, reduced for 62% and low for 23% of players. Higher EA was observed on rest days compared to others (P<0.05). EA was higher for the light compared to the heavy training day (P<0.001). EEE differed significantly between days (P<0.05). EI (2124 ± 444 kcal), carbohydrate (3.31 ± 0.64 g·kg·day^-1) and protein (1.83 ± 0.41 g·kg·day^-1) intake remained similar (P>0.05). Survey data revealed 23% scored ≥8 on the Low Energy Availability in Females Questionnaire and met criteria for low RMR (ratio <0.90). Relationships between EA and risk factors were inconclusive. Most players displayed reduced EA and did not alter EI or carbohydrate intake according to training or match demands. Although cases of low EA were identified, further work is needed to investigate possible long-term effects and risk factors of low and reduced EA separately to inform player recommendations.

Contraception in adolescents with anorexia nervosa. Is there evidence for a negative impact of combined hormonal contraceptives on bone mineral density and the course of the disease?

Objective: Adolescents with anorexia nervosa (AN) are at increased risk of unplanned pregnancies and bone loss, due to low oestrogen levels and low use of efficient contraception. The negative impact of combined hormonal contraceptives (CHC) on peak bone mass during adolescence might limit wider use in anorexic women. Another issue limiting CHC use is the concern, that CHC-induced cyclic bleeding reduces the motivation for further weight gain and thus exerts a negative impact on recovery. We wanted to find evidence based answers about the impact of CHC use on bone health and course of the disease in adolescents with AN.Methods: We performed a narrative review of the current literature investigating the effect of CHC or progestin-only contraceptives on bone density, body shape and course of disease in young women with anorexia.Results: There is no evidence that CHC use aggravates the bone loss associated with AN. In long-term users CHC exert a protective effect. Anorexic women using CHC showed at least the same or a greater weight gain in comparison with controls. Eating disorder attitudes did not worsen.Conclusion: We conclude, that at present there is no evidence, that use of CHC by AN patients has a negative impact on bone density or the course of disease.

Oral ethinyl estradiol treatment in women with cystic fibrosis is associated with lower bone mineral density

Objective

The purpose of this study was to determine whether estrogen supplementation primarily from oral contraceptive pills compared to no estrogen supplementation is associated with differences in mean bone mineral density (BMD) measured by DXA in a cross-sectional study of women with cystic fibrosis (CF).

Methods

In this cross-sectional study of women with CF followed at a single center, we analyzed 49 women with CF ages 18–50 years with a documented DXA. BMD of women with CF taking estrogen supplementation was compared to BMD of women with CF not taking estrogen supplementation.

Results

Twelve women with CF were taking estrogen supplementation with mean dose of 23.3 mcg/day (SD 6.9 mcg/day) of ethinyl estradiol. There were no statistically significant differences between demographics of the 12 women with CF taking estrogen supplementation compared to the 37 women with CF not taking estrogen supplementation. Women taking estrogen had lower mean lumbar spine Z-score: −0.7 ± 0.7, compared to women not taking estrogen, Z-score: −0.04 ± 1.0 (p-value 0.046). Women taking estrogen had lower mean BMD at the lumbar spine: 0.952 ± 0.086 g/cm², compared to women not taking estrogen: 1.023 ± 0.105 g/cm² (p-value 0.038). Similar trends were seen at the total hip and femoral neck.

Conclusion

Low-dose estrogen supplementation in premenopausal women with CF was associated with lower BMD compared to no estrogen supplementation in a similar group of premenopausal young women with CF. Future studies are needed to investigate the optimal formulation, route of administration, and dose to accrue and preserve bone mass in premenopausal women with CF.

The Utility of DXA Assessment at the Forearm, Proximal Femur, and Lateral Distal Femur, and Vertebral Fracture Assessment in the Pediatric Population: 2019 ISCD Official Position

Dual-energy X-ray absorptiometry (DXA) is widely used in the evaluation of bone fragility in children. Previous recommendations emphasized total body less head and lumbar spine DXA scans for clinical bone health assessment. However, these scan sites may not be possible or optimal for all groups of children with conditions that threaten bone health. The utility of DXA scans of the proximal femur, forearm, and radius were evaluated for adequacy of reference data, precision, ability of predict fracture, and applicability to all, or select groups of children. In addition, the strengths and limitations of vertebral fracture assessment by DXA were evaluated. The new Pediatric Positions provide guidelines on the use of these additional measures in the assessment of skeletal health in children.

Suboptimal bone microarchitecure in adolescent girls with obesity compared to normal-weight controls and girls with anorexia nervosa

BACKGROUND

Despite their higher areal bone mineral density (aBMD), adolescents with obesity (OB) have an increase in fracture risk, particularly of the extremities, compared with normal-weight controls. Whereas bone parameters that increase fracture risk are well characterized in anorexia nervosa (AN), the other end of nutritional spectrum, these data are lacking in adolescents with obesity.

OBJECTIVE

Our objective was to compare bone parameters in adolescent girls across the nutritional spectrum, to determine whether suboptimal bone adaptation to increased body weight may explain the increased fracture risk in OB.

METHODS

We assessed bone endpoints in 153 adolescent girls 14-21 years old: 50 OB, 48 controls and 55 AN. We used (i) DXA to assess aBMD at the lumbar spine, proximal femur and whole body, and body composition, (ii) high resolution peripheral quantitative CT (HRpQCT) to assess bone geometry, microarchitecture and volumetric BMD (vBMD), and (iii) finite element analysis to assess failure load (a strength estimate) at the distal radius and tibia. All aBMD, microarchitecture and FEA analyses were controlled for age and race.

RESULTS

Groups did not differ for age or height. Areal BMD Z-scores at all sites were highest in OB, intermediate in controls and lowest in AN (p < 0.0001). At the radius, cortical area and thickness were higher in OB compared to AN and control groups (p = 0.001) while trabecular area did not differ across groups. Compared to controls, OB had higher cortical porosity (p = 0.003), higher trabecular thickness (p = 0.024), and higher total, cortical and trabecular vBMD and rod BV/TV (p < 0.04). Plate BV/TV did not differ in OB vs. controls, but was higher than in AN (p = 0.001). At the tibia, total, cortical, and trabecular area and cortical thickness were higher in OB vs. controls and AN (p < 0.005). OB also had higher cortical porosity (p < 0.007) and lower trabecular thickness (p < 0.02) than the other two groups. Trabecular number, total and trabecular vBMD, and rod BV/TV were higher in OB vs. controls and AN (p < 0.02), while cortical vBMD and plate BV/TV did not differ in OB vs. the other two groups. Finally, failure load (a strength estimate) was higher in OB at the radius and tibia compared to controls and AN (p < 0.004 for all). However, after adjusting for body weight, failure load was lower in OB vs. controls at both sites (p < 0.05), and lower than in AN at the distal tibia.

CONCLUSION

Not all bone parameters demonstrate appropriate adaptation to higher body weight. Cortical porosity and plate BV/TV at the radius and tibia, and cortical vBMD and trabecular thickness at the tibia are particularly at risk. These effects may contribute to the higher risk for fracture reported in OB vs. controls.