Assessment of sex differences in bone deficits among adolescents with anorexia nervosa

Unique considerations for the medical care of restrictive eating disorders in children and young adolescents

BACKGROUND

The medical complications of eating disorders are often approached through an age-neutral lens. However, children and young adolescents may have unique medical complications related to the energy needs and timing of growth and development. Providers caring for patients in this vulnerable age range should understand how to identify, approach, and manage these potential age-related complications.

REVIEW

Evidence continues to accumulate that increasingly younger patients are being diagnosed with eating disorders. These children and young adolescents have significant risk for unique and potentially irreversible medical complications. Without early identification and treatment, restrictive eating disorders may negatively impact linear growth, bone development and brain maturation in children and young adolescents. Additionally, due to the energy needs of growth and development, unique considerations exist for the use of acute medical stabilization and the identification of patients at risk for refeeding syndrome with initial nutritional rehabilitation. This review presents an approach to the evaluation and management of children and young adolescents with eating disorders.

CONCLUSION

Children and young adolescents with restrictive eating disorders may have unique medical complications related to the energy needs and timing of linear growth and pubertal development. Significant risk exists for irreversible medical complications of impaired growth, bone, and brain health. Increased awareness of the energy needs for growth and development may improve early recognition, appropriate intervention, and future outcomes for children and young adolescents with restrictive eating disorders.

Clinician confidence and practices for evaluating bone health in male and female adolescents and young adults with an eating disorder

Extensive literature exists on bone health in females with an eating disorder, yet few have studied males. Our study assessed clinician confidence and current practices for assessing bone health in patients with an eating disorder. We also aimed to identify any differences in practice based on patient sex. Our 31-item survey, distributed to adolescent clinicians in the United States via the Society for Adolescent Health and Medicine (SAHM) listserv, assessed clinician confidence and practices for assessing bone mineral density in both male and female adolescents with an eating disorder. Findings showed that clinicians (n = 104) were less confident in assessing bone mineral density in males compared to females (p < .001), yet there was no significant difference in rates of obtaining a DXA (p = .390). Although clinicians are less confident assessing bone health in males with an eating disorder than females, this does not appear to result in screening differences.

Sex differences and associations between zinc deficiency and anemia among hospitalized adolescents and young adults with eating disorders

PURPOSE

To determine sex differences in and associations between zinc deficiency and anemia among adolescents and young adults hospitalized for medical complications of eating disorders.

METHODS

We retrospectively reviewed electronic medical records of 601 patients aged 9-25 years admitted to the University of California, San Francisco Eating Disorders Program for medical instability, between May 2012 and August 2020. Descriptive statistics, crude, and adjusted logistic regression models were used to assess the association between zinc deficiency (< 55 mcg/dL) and anemia (< 13.6 g/dL in males [M] and < 11.8 g/dL in females [F]).

RESULTS

A total of 87 males and 450 females met eligibility criteria (age 15.98 ± 2.81, 59.4% anorexia nervosa; admission body mass index 17.49 ± 2.82). In unadjusted comparisons, plasma zinc in males and females were not statistically different (M 64.88 ± 14.89 mcg/dL vs F 63.81 ± 13.96 mcg/dL, p = 0.517); moreover, there were no differences in the percentage of males and females with zinc deficiency (M 24.14% vs F 24.89%). However, a greater percentage of males than females were anemic (M 50.00% vs F 17.61%, p < 0.001), with similar findings in the subgroup with anorexia nervosa. In logistic regression models stratified by sex and eating disorder diagnosis, zinc deficiency was significantly associated with anemia in males (AOR 3.43, 95% CI 1.16, 10.13), but not females (AOR 1.47, 95% CI 0.86, 2.54).

CONCLUSIONS

For the first time, we demonstrate that zinc deficiency is equally severe in males compared to females hospitalized with medical complications from eating disorders, with nearly a quarter of inpatients experiencing zinc deficiency. Anemia is more common in males than females hospitalized with eating disorders.

LEVEL OF EVIDENCE

Level V: descriptive cross-sectional study.

Assessment of vitamin D among male adolescents and young adults hospitalized with eating disorders

PURPOSE

Medical complications of eating disorders in males are understudied compared to females, as is the case of vitamin D deficiency. The aim of this study was to assess vitamin D levels among male and female adolescents and young adults hospitalized for medical complications of eating disorders.

METHODS

We retrospectively reviewed electronic medical records of patients aged 9-25 years (N = 565) admitted to the University of California, San Francisco Eating Disorders Program for medical instability, between May 2012 and August 2020. Serum vitamin D (25-hydroxy) level was assessed at admission as was history of prior calcium, vitamin D, or multivitamin supplementation. Linear regression was used to assess factors associated with vitamin D levels.

RESULTS

A total of 93 males and 472 females met eligibility criteria (age 15.5 ± 2.8, 58.8% anorexia nervosa; admission body mass index 17.6 ± 2.91). Among male participants, 44.1% had 25-hydroxyvitamin D levels < 30 ng/mL, 18.3% had 25-hydroxyvitamin D levels < 20 ng/mL, and 8.6% had 25-hydroxyvitamin D levels < 12 ng/mL. There were no significant differences in 25-hydroxyvitamin D levels in males compared to females, except that a lower proportion (1.9%) of female participants had 25-hydroxyvitamin D levels < 12 ng/mL (p = 0.001). Only 3.2% of males reported calcium or vitamin D-specific supplementation prior to hospital admission, while 8.6% reported taking multivitamins. White race, prior calcium/vitamin D supplementation, and higher calcium levels were associated with higher vitamin D levels on admission.

CONCLUSIONS

Nearly half of patients admitted to the hospital for malnutrition secondary to eating disorders presented with low 25-hydroxyvitamin D levels; males were more likely than females to have severe vitamin D deficiency. These findings support vitamin D assessment as part of the routine medical/nutritional evaluation for hospitalized eating disorder patients, with particular attention on male populations.

Anorexia Nervosa and Osteoporosis

Patients with anorexia nervosa (AN) often experience low bone mineral density (BMD) and increased fracture risk, with low body weight and decreased gonadal function being the strongest predictors of the observed bone mineral deficit and fractures. Other metabolic disturbances have also been linked to bone loss in this group of patients, including growth hormone resistance, low insulin-like growth factor-1 (IGF-1) concentrations, low leptin concentrations, and hypercortisolemia. However, these correlations lack definitive evidence of causality. Weight restoration and resumption of menstrual function have the strongest impact on increasing BMD. Other potential treatment options include bisphosphonates and teriparatide, supported by data from small clinical trials, but these agents are not approved for the treatment of low BMD in adolescents or premenopausal women with AN.

The Reproductive Impact of Eating Disorders in Adolescents

Eating disorders are common, chronic illnesses that frequently arise during adolescence. Because of the impact on nutrition, individuals with eating disorders have significant health consequences, including effects on reproductive health. Adolescent women with eating disorders frequently have menstrual irregularities, though the causes of these abnormalities are complex and vary depending on the type of eating disorder. Teens with eating disorders may have changes in current and future fertility, and eating disorders during pregnancy can have medical and psychologic impacts for both mother and child. Though not well researched, eating disorders in men can affect reproductive health and potentially impact fertility. Lastly, eating disorders in adolescents can have significantly deleterious, irreversible effects on bone health.

Clinician practices assessing hypothalamic-pituitary-gonadal axis suppression in adolescents with an eating disorder

OBJECTIVE

Although extensive literature exists on hypothalamic-pituitary-gonadal (HPG) axis suppression in females with an eating disorder, there are few studies in males. Our study aimed to determine clinician practices for the assessment of HPG axis suppression and to identify differences in practice based on the sex of the patient.

METHOD

Our 31-item survey queried clinicians about confidence level and practices for assessing HPG suppression in male compared to female patients.

RESULTS

Findings showed that clinicians (n = 104) were less likely to evaluate HPG suppression in males compared to females, including assessment of sexual maturity rating (p < .050), screening of decreased libido compared to amenorrhea (p < .001) and lab assessment (luteinizing hormone and follicular-stimulating hormone: p < .001; estradiol/testosterone: p < .010; TSH: p < .050). Participants also felt less confident evaluating male patients (p < .001) and requested better screening tools for males (p < .001).

DISCUSSION

Our data suggest that clinician practices differ based on patient sex and that clinicians request tools for HPG suppression assessment in males. This is the first study examining specific practices and comfort levels of clinicians when assessing HPG axis suppression. Findings suggest that more guidance on the management of male patients may be needed to standardize care and to prevent short and long-term sequela of malnutrition.

Last word: A call to develop specific medical treatment guidelines for adolescent males with eating disorders

Males with eating disorders are underdiagnosed and undertreated, which may be a result of inadequate guidance and training to assess and treat eating disorders for medical professionals. This may be particularly problematic for adolescent males given the focus of eating disorders research and treatment on adolescent females. Furthermore, there is a paucity of research to guide screening, medical treatment, and training of health professions in adolescent males with eating disorders. The development of eating disorders education and training for medical professionals are included in the 21st Century Cures Act, which further emphasizes the opportunity to develop treatment guidelines individualized to male patients. This last word calls for the development of specific medical treatment guidelines for adolescent males with eating disorders.

Eating disorders in adolescent boys and young men: an update

PURPOSE OF REVIEW

To review the recent literature on eating disorders and disordered eating behaviors among adolescent boys and young men, including epidemiology, assessment, medical complications, treatment outcomes, and special populations.

RECENT FINDINGS

Body image concerns in men may involve muscularity, and muscle-enhancing goals and behaviors are common among adolescent boys and young men. Recent measures, such as the Muscularity Oriented Eating Test (MOET) have been developed and validated to assess for muscularity-oriented disordered eating. Medical complications of eating disorders can affect all organ systems in male populations. Eating disorders treatment guidance may lack specificity to boys and men, leading to worse treatment outcomes in these population. Male populations that may have elevated risk of eating disorders and disordered eating behaviors include athletes and racial/ethnic, sexual, and gender minorities.

SUMMARY

Eating disorders and disordered eating behaviors in boys and men may present differently than in girls and women, particularly with muscularity-oriented disordered eating. Treatment of eating disorders in boys and men may be adapted to address their unique concerns.

Associations between exercise, bone mineral density, and body composition in adolescents with anorexia nervosa

OBJECTIVE

To identify the effect of duration of weight-bearing exercise and team sports participation on bone mineral density (BMD) and body composition among adolescents with anorexia nervosa (AN).

METHOD

We retrospectively reviewed electronic medical records of all patients 9-20 years old with a DSM-5 diagnosis of AN evaluated by the Stanford Eating Disorders Program (1997-2011) who underwent dual-energy X-ray absorptiometry.

RESULTS

A total of 188 adolescents with AN were included (178 females and 10 males). Using multivariate linear regression, duration of weight-bearing exercise (B = 0.15, p = 0.005) and participation in team sports (B = 0.53, p = 0.001) were associated with higher BMD at the hip and team sports (B = 0.39, p = 0.006) were associated with higher whole body BMC, controlling for covariates. Participation in team sports (B = - 1.06, p = 0.007) was associated with greater deficits in FMI Z-score. LBMI Z-score was positively associated with duration of weight-bearing exercise (B = 0.10, p = 0.018) and may explain the relationship between exercise and bone outcomes.

CONCLUSION

Duration of weight-bearing exercise and team sports participation may be protective of BMD at the hip and whole body BMC, while participation in team sports was associated with greater FMI deficits among adolescents with AN.

LEVEL OF EVIDENCE

Level V, descriptive retrospective study.

An update on the medical consequences of anorexia nervosa

PURPOSE OF REVIEW

The diagnosis of anorexia nervosa is associated with the highest mortality rate of any psychiatric disorder, mainly caused by medical complications.The purpose of this article is to review the common medical consequences of anorexia nervosa focusing on the special considerations related to children and adolescents and recent updates on the pathophysiology of these complications and their prognosis significance.

RECENT FINDINGS

The main findings were related to the diagnostic and prognostic value of hypokalaemia, QTc prolongation, hypoglycaemia and orthostatic changes. A new modality to evaluate the heart in anorexia nervosa was explored (2DSTE) as well. Bone mineral density (BMD) loss is one of the few nonreversible consequences of anorexia nervosa. BMD loss does not seem to be significantly related to sex or to cut-off low-weight parameters in teenagers with anorexia nervosa, but rather to the amount of weight loss they have experienced. Brain volume deficits might be another irreversible complication in adolescents with anorexia nervosa.

SUMMARY

It is crucial for any healthcare provider to be informed about the medical consequences of anorexia nervosa, not only because they can be devastating, but also because they can play an essential role in motivating patients to get treated.

Bone mineral density and estimated hip strength in men with anorexia nervosa, atypical anorexia nervosa and avoidant/restrictive food intake disorder

OBJECTIVE

Few bone mineral density (BMD) data are available in men with anorexia nervosa (AN), and none in those with atypical AN (ATYP) (AN psychological symptoms without low weight) or avoidant/restrictive food intake disorder (ARFID) (restrictive eating without AN psychological symptoms). We investigated the prevalence and determinants of low BMD and estimated hip strength in men with these disorders.

DESIGN

Cross-sectional: two centres.

PATIENTS

A total of 103 men, 18-63 years: AN (n = 26), ARFID (n = 11), ATYP (n = 18), healthy controls (HC) (n = 48).

MEASUREMENTS

Body composition, BMD and estimated hip strength (section modulus and buckling ratio) by DXA (Hologic). Serum 25OH vitamin D was quantified, as was daily calcium intake in a subset of subjects.

RESULTS

Mean BMI was lowest in AN and ARFID, higher in ATYP and highest in HC (AN 14.7 ± 1.8, ARFID 15.3 ± 1.5, ATYP 20.6 ± 2.0, HC 23.7 ± 3.3 kg/m² ) (P < 0.0005). Mean BMD Z-scores at spine and hip were lower in AN and ARFID, but not ATYP, than HC (postero-anterior (PA) spine AN -2.05 ± 1.58, ARFID -1.33 ± 1.21, ATYP -0.59 ± 1.77, HC -0.12 ± 1.17) (P < 0.05). 65% AN, 18% ARFID, 33% ATYP and 6% HC had BMD Z-scores <-2 at ≥1 site (AN and ATYP vs HC, P < 0.01). Mean section modulus Z-scores were lower in AN than HC (P < 0.01). Lower BMI, muscle mass and vitamin D levels (R = 0.33-0.64), as well as longer disease duration (R = -0.51 to -0.58), were associated with lower BMD (P < 0.05).

CONCLUSIONS

Men with AN, ARFID and ATYP are at risk for low BMD. Men with these eating disorders who are low weight, or who have low muscle mass, long illness duration and/or vitamin D deficiency, may be at particularly high risk.

Comparisons of bone density and body composition among adolescents with anorexia nervosa and atypical anorexia nervosa

OBJECTIVE

To compare bone mineral density (BMD) and body composition among adolescents: (a) with atypical anorexia nervosa (AAN) versus anorexia nervosa (AN) and (b) those with and without a prior history of overweight.

METHOD

Electronic medical records of patients 9-20 years with AN or AAN who underwent dual-energy x-ray absorptiometry scans were retrospectively reviewed and analyzed.

RESULTS

A total of 286 adolescents with AN or AAN were included. In linear regression models, AAN was associated with greater Z-scores in whole body bone mineral content (BMC, B = 0.88, p < 0.001), lumbar spine BMD (B = 0.79, p = 0.002), femoral neck BMD (B = 0.670, p = 0.009); fat mass index (B = 1.33, p = 0.003), and lean body mass index (LBMI, B = 1.10, p < 0.001) compared to AN, adjusting for age, sex, and duration of illness. A prior overweight history was associated with greater Z-scores in whole body BMC; lumbar spine BMD, total hip BMD, femoral neck BMD, and LBMI.

DISCUSSION

Adolescents with AAN had higher BMD Z-scores than adolescents with AN; adolescents with a prior overweight history had greater BMD Z-scores than adolescents without a prior overweight history. These findings may inform clinical guidelines for the medical management of AAN.

Longitudinal changes in bone parameters in young girls with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) during childhood and adolescence has been reported to adversely affect bone health, but few studies have investigated longitudinal changes.

METHOD

DXA-derived bone parameters and body composition were retrospectively assessed in 111 young girls with AN with a median age of 15.4 years (10.9, 19.8). In 68 (61%) vertebral fracture assessment (VFA) was performed and in 31 (28%), a follow-up DXA was performed. Correlations with growth, changes in body composition and effects of illness duration and menstruation were examined. Size adjusted DXA standard deviation scores were calculated for total body (TB) less head bone mineral content (TBLH-BMC) and lumbar spine bone mineral apparent density (LS-BMAD).

RESULTS

Mean (range) bone area (BA) for height centile was 27.1 (0-97), and mean lean mass for height centile was 28.8 (0-95) at baseline. Mean (range) LS BMAD was -1.0 (-2.6, 0.8) SDS at first and - 1.2 (-3.0, -0.2) at second DXA (p = 0.023). On follow up, lean mass for height increased from 27th centile (0, 75) to 40th centile (0, 70) (p = 0.006), and fat mass for height increased from 55 g/cm to 67 g/cm (11.3, 124.2) (p < 0.001). Duration of illness was the only negative predictor of LS BMAD (p < 0.0001). Change in height SDS was the only positive predictor of change in TBLH-BMC (r = 0.384, p = 0.037), and change in LS BMAD (r-0.934, p < 0.0001). Of 68 patients who had VFA, 4 (5.9%) had a mild vertebral fracture.

CONCLUSION

Bones are smaller and less dense in childhood/adolescent AN compared to healthy adolescents. Although there are significant gains in lean mass and fat mass, over time, BMAD SDS decreases slightly. Improvement in BMAD SDS is related to improvement in height SDS.

Differential Risk Factors for Unhealthy Weight Control Behaviors by Sex and Weight Status Among U.S. Adolescents

PURPOSE

To determine if previously reported risk factors for the development of unhealthy weight control behaviors differ by sex and weight status using a nationally representative longitudinal sample of adolescents followed through young adulthood.

METHODS

We used nationally representative longitudinal cohort data collected from baseline (11-18 years old, 1994-1995, Wave I) and seven-year follow-up (18-24 years old, 2001-2002, Wave III) of the National Longitudinal Study of Adolescent to Adult Health (Add Health). We examined potential risk factors (adverse childhood events and adolescent family, school, body image, and mental health factors) for the development of unhealthy weight control behaviors including vomiting, fasting/skipping meals, or laxative/diuretic use to lose weight at seven-year follow-up in young adulthood.

RESULTS

Of the 14,322 included subjects, 11% reported unhealthy weight control behavior at follow-up in young adulthood, with the highest proportion (23.7%) among overweight/obese females and the lowest proportion (3.7%) among underweight/normal weight males. All adolescent family factors were significantly associated with unhealthy weight control behaviors in underweight/normal weight females, whereas none were significantly associated in overweight/obese males. Similar trends were noted for adverse childhood events, and adolescent school and community factors. Adolescent self-perception of being overweight was associated with young adult unhealthy weight control behaviors among all subgroups.

CONCLUSIONS

Risk factors for unhealthy weight control behaviors may differ based on sex and weight status. Screening, prevention, and treatment interventions for unhealthy weight control behaviors in adolescents and young adults may need to be tailored based on sex and weight status.

Prevalence and Correlates of Disordered Eating Behaviors Among Young Adults with Overweight or Obesity

BACKGROUND

Clinical and community samples indicate that eating disorders (EDs) and disordered eating behaviors (DEBs) may co-occur among adolescents and young adults at a weight status classified as overweight or obese.

OBJECTIVE

To determine the prevalence of EDs and DEBs among young adults at a weight status classified as overweight or obese using a nationally representative sample and to characterize differences in prevalence by sex, race/ethnicity, sexual orientation, and socioeconomic status.

DESIGN

Cross-sectional nationally representative data collected from Wave III of the National Longitudinal Study of Adolescent to Adult Health (Add Health).

PARTICIPANTS

Young adults ages 18-24 years old.

MAIN MEASURES

ED diagnosis and DEBs (self-reported binge eating or unhealthy weight control behaviors including vomiting, fasting/skipping meals, or laxative/diuretic use to lose weight). Covariates: age, sex, race/ethnicity, sexual orientation, weight status, and education.

KEY RESULTS

Of the 14,322 young adults in the sample, 48.6% were at a weight status classified as overweight or obese. Compared to young adults at a weight status classified as underweight or normal weight, those at a weight status classified as overweight or obese reported a higher rate of DEBs (29.3 vs 15.8% in females, 15.4 vs 7.5% in males). Logistic regression analyses demonstrated that odds of engaging in DEBs were 2.32 (95% confidence interval 2.05-2.61) times higher for females compared to males; 1.66 (1.23-2.24) times higher for Asian/Pacific Islander compared to White; 1.62 (1.16-2.26) times higher for homosexual or bisexual compared to heterosexual; 1.26 (1.09-1.44) times higher for high school or less versus more than high school education; and 2.45 (2.16-2.79) times higher for obesity compared to normal weight, adjusting for all covariates.

CONCLUSIONS

The high prevalence of DEBs particularly in young adults at a weight status classified as overweight or obese underscores the need for screening, referrals, and tailored interventions for DEBs in this population.

Bone metabolism in anorexia nervosa and hypothalamic amenorrhea

Anorexia nervosa (AN) and hypothalamic amenorrhea (HA) are states of chronic energy deprivation associated with severely compromised bone health. Poor bone accrual during adolescence followed by increased bone loss results in lifelong low bone density, degraded bone architecture, and higher risk of fractures, despite recovery from AN/HA. Amenorrhea is only one of several compensatory responses to the negative energy balance. Other hypothalamic-pituitary hormones are affected and contribute to bone deficits, including activation of hypothalamic-pituitary-adrenal axis and growth hormone resistance. Adipokines, particularly leptin, provide information on fat/energy stores, and gut hormones play a role in the regulation of appetite and food intake. Alterations in all these hormones influence bone metabolism. Restricted in scope, current pharmacologic approaches to improve bone health have had overall limited success.

Anorexia Nervosa and Bone

Anorexia nervosa (AN), a psychiatric disorder characterized by altered body image, food restriction and low body weight, is associated with low bone mineral density and increased fracture risk. Despite broadening the definition of AN in the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition, the prevalence of low bone mass remains high, suggesting we continue to capture individuals at high risk for bone loss. Many of the endocrine disturbances adaptive to the state of chronic starvation are thought to be causal in impaired skeletal integrity in females and males with AN. Understanding mechanisms responsible for impaired bone quality is important given the disease's severity and chronicity. Further research is needed to formulate optimal treatment strategies to reduce fracture risk.

Characterization and correlates of exercise among adolescents with anorexia nervosa and bulimia nervosa

OBJECTIVE

To characterize exercise behaviors among adolescents with anorexia nervosa (AN), atypical AN, or bulimia nervosa (BN), and determine associations between exercise and medical risk.

STUDY DESIGN

Cross-sectional electronic medical records of all patients evaluated by the Eating Disorder Program at Stanford between January 1997 and February 2011 were retrospectively reviewed.

RESULTS

1,083 subjects (961 females, 122 males; mean age 15.6) met eligibility criteria. Most patients (89.7%) reported exercise (mean 7.0 h per week over mean 5.4 days per week) prior to presentation. Running (49.9%), calisthenics (40.7%), walking (23.4%), soccer (20.9%), and swimming (18.2%) were the most common exercises; a majority (60.6%) reported team sport participation. Males were less likely to report team exercise (p = .005). Bradycardia (heart rate <50) at presentation was associated with team sport participation (adjusted odds ratio [AOR] 1.66, 95% confidence interval [CI] 1.02-2.72) and hours of exercise per week (AOR 1.05, 95% CI 1.02-1.09), controlling for diagnosis, sex, age, duration of illness, rate of weight loss, and percent median body mass index (%mBMI).

DISCUSSION

Adolescents with AN, atypical AN, and BN reported high levels of exercise. Females reported more team sport participation. Greater exercise frequency and team sport participation were associated with bradycardia. Further studies assessing the relationship between exercise and bradycardia may help inform the medical management of adolescents with these eating disorders who are more physically active.

Assessment of Sex Differences in Fracture Risk Among Patients With Anorexia Nervosa: A Population-Based Cohort Study Using The Health Improvement Network

Though previous studies have demonstrated an increased fracture risk in females with anorexia nervosa (AN), fracture risk in males is not well characterized. The objective of this study was to examine sex differences in fracture risk and site-specific fracture incidence in AN. We performed a population-based retrospective cohort study using The Health Improvement Network (THIN; a large database of anonymized electronic medical records collected at primary care clinics throughout the United Kingdom). The median calendar year for the start of the observation period was 2004-2005. We identified 9239 females and 556 males <60 years of age with AN, and 97,889 randomly selected sex-, age-, and practice-matched participants without eating disorders (92,329 females and 5560 males). Multivariable Cox regression was used to estimate the hazard ratio (HR) for incident fracture. Median age at start of observation was 29.8 years in females and 30.2 years in males. The HR for fracture associated with AN differed by sex and age (interaction p = 0.002). Females with AN had an increased fracture risk at all ages (HR, 1.59; 95% confidence interval [CI], 1.45 to 1.75). AN was associated with a higher risk of fracture among males >40 years of age (HR, 2.54; 95% CI, 1.32 to 4.90; p = 0.005) but not among males ≤40 years. Females with AN had a higher risk of fracture at nearly all anatomic sites. The greatest excess fracture risk was noted at the hip/femur (HR, 5.59; 95% CI, 3.44 to 9.09) and pelvis (HR, 4.54; 95% CI, 2.42 to 8.50) in females and at the vertebrae (HR, 7.25; 95% CI, 1.21 to 43.45) for males with AN. AN was associated with higher incident fracture risk in females across all age groups and in males >40 years old. Sites of highest fracture risk include the hip/femur and pelvis in females and vertebrae in males with AN. © 2016 American Society for Bone and Mineral Research.

Assessment of Sex Differences in Body Composition Among Adolescents With Anorexia Nervosa

PURPOSE

To compare deficits in fat mass (FM) and lean body mass (LM) among male and female adolescents with anorexia nervosa (AN) and to identify other covariates associated with body composition.

METHODS

We retrospectively reviewed electronic medical records of all subjects aged 9-20 years with a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition diagnosis of AN and dual-energy x-ray absorptiometry scans after initial evaluation at Stanford between March 1997 and February 2011. From the dual-energy x-ray absorptiometry scans, LM and FM results were converted to age-, height-, sex-, and race-specific Z-scores for age using the National Health and Nutrition Examination Survey reference data.

RESULTS

A total of 16 boys and 119 girls with AN met eligibility criteria. The FM Z-score in girls with AN (-3.24 ± 1.50) was significantly lower than that in boys with AN (-2.41 ± .96) in unadjusted models (p = .007). LM was reduced in both girls and boys with AN, but there was no significant sex difference in LM Z-scores. In multivariate models, lower percentage median body mass index was significantly associated with lower FM Z-scores (β = .08, p < .0001) and lower LM Z-score (β = .03, p = .0002), whereas lower whole body bone mineral content Z-score was significantly associated with lower LM Z-score (β = .21, p = .0006).

CONCLUSIONS

FM deficits in girls were significantly greater than those in boys with AN in unadjusted models; however, the degree of malnutrition appeared to be the primary factor accounting for this difference. There were no significant sex differences in FM or LM in adjusted models.