Low bone mineral density in anorexia nervosa: Treatments and challenges

Adolescent displaced lateral-end clavicle fractures are not comparable to the adult variant. Epidemiology, fracture patterns and outcome of non-operative management

Background

The primary aim of this study was to determine the epidemiology of lateral-end clavicle fractures in adolescents. The secondary aim was to assess the outcome following non-operative management.

Methods

A retrospective review of all adolescent clavicle fractures over a 10-year period was undertaken. Fracture classification, demographics, management, and complications were analysed. Functional outcomes were undertaken with the Quick Disabilities of Arm, Shoulder and Hand and EuroQol five-dimension at mean 8.8 years post-injury.

Results

In total, 677 clavicle fractures were analysed, 8.7% were lateral-end fractures (n = 59/677). The median age was 14.6 (range: 13-17) and 92% were male (n = 54/59). The incidence was 0.17 per 100,000 per year. All displaced physeal fractures (Neer IV n = 14) were managed non-operatively and of the six followed-up, all united with good outcomes. The adult type displaced fracture (Neer II) occurred in fifteen fractures, five underwent operative fixation and ten were managed non-operatively with one subsequent nonunion (n = 1/10). Those patients that underwent non-operative management (response n = 5/10, 50%) reported a median Quick Disabilities of Arm, Shoulder and Hand of 2.3 but approximately 40% reported cosmetic and outcome dissatisfaction at long-term follow-up.

Conclusion

Displaced Neer II lateral-end clavicle fractures are rare in the adolescent population. Although nonunion is rare, some dissatisfaction with cosmesis persists at long-term follow-up despite good functional outcomes with non-operative management.

Neuroendocrine adaptations to starvation

Famine and starvation have punctuated the evolutionary past of the human species. As such, we have developed hormonal responses to undernutrition that minimize energy expenditure on processes that are not critical for the survival of the individual, such as reproduction. In this review, we discuss neuroendocrine adaptations to starvation including hypogonadotropic hypogonadism, growth hormone resistance, hypercortisolemia, and the downregulation of the hypothalamic-pituitary-thyroid axis. We review the time-course of these adaptations by describing studies involving the short-term fasting of healthy individuals as well as studies describing the hormonal changes in states of chronic undernutrition, using individuals with anorexia nervosa as a model of chronic starvation. Lastly, we review representative clinical effects of chronic undernutrition.

Bone adaptation and osteoporosis prevention in hibernating mammals

Hibernating bears and rodents have evolved mechanisms to prevent disuse osteoporosis during the prolonged physical inactivity that occurs during hibernation. Serum markers and histological indices of bone remodeling in bears indicate reduced bone turnover during hibernation, which is consistent with organismal energy conservation. Calcium homeostasis is maintained by balanced bone resorption and formation since hibernating bears do not eat, drink, urinate, or defecate. Reduced and balanced bone remodeling protect bear bone structure and strength during hibernation, unlike the disuse osteoporosis that occurs in humans and other animals during prolonged physical inactivity. Conversely, some hibernating rodents show varying degrees of bone loss such as osteocytic osteolysis, trabecular loss, and cortical thinning. However, no negative effects of hibernation on bone strength in rodents have been found. More than 5000 genes in bear bone tissue are differentially expressed during hibernation, highlighting the complexity of hibernation induced changes in bone. A complete picture of the mechanisms that regulate bone metabolism in hibernators still alludes us, but existing data suggest a role for endocrine and paracrine factors such as cocaine- and amphetamine-regulated transcript (CART) and endocannabinoid ligands like 2-arachidonoyl glycerol (2-AG) in decreasing bone remodeling during hibernation. Hibernating bears and rodents evolved the capacity to preserve bone strength during long periods of physical inactivity, which contributes to their survival and propagation by allowing physically activity (foraging, escaping predators, and mating) without risk of bone fracture following hibernation. Understanding the biological mechanisms regulating bone metabolism in hibernators may inform novel treatment strategies for osteoporosis in humans.

Aging of Skeletal Stem Cells

The skeletal system is generated and maintained by its progenitors, skeletal stem cells (SSCs), across the duration of life. Gradual changes associated with aging result in significant differences in functionality of SSCs. Declines in bone and cartilage production, increase of bone marrow adipose tissue, compositional changes of cellular microenvironments, and subsequent deterioration of external and internal structures culminate in the aged and weakened skeleton. The features and mechanisms of skeletal aging, and of its stem and progenitor cells in particular, are topics of recent investigation. The discovery of functionally homogeneous SSC populations with a defined cell surface phenotype has allowed for closer inspection of aging in terms of its effects on transcriptional regulation, cell function, and identity. Here, we review the aspects of SSC aging on both micro- and macroscopic levels. Up-to-date knowledge of SSC biology and aging is presented, and directions for future research and potential therapies are discussed. The realm of SSC-mediated bone aging remains an important component of global health and a necessary facet in our understanding of human aging.

Estrogen for the Treatment of Low Bone Mineral Density in Anorexia Nervosa

Anorexia nervosa is a disorder of chronic, self-induced negative energy balance which typically results in a low body weight. Functional hypothalamic amenorrhea is an adaptive response to states of negative energy balance and chronic undernutrition. A majority of women with anorexia nervosa are amenorrheic with resultant hypoestrogenemia, and longer durations of amenorrhea are associated with lower bone mineral density in this population. In this review, we highlight studies that have investigated the effects of estrogen replacement on bone mineral density in anorexia nervosa, including prospective and randomized studies that show no benefit to treatment with oral estrogen with respect to bone mineral density in either adolescent girls or women with anorexia nervosa. We also review data from a randomized, placebo-controlled study in adolescent girls and a prospective, open-label pilot study in women with anorexia nervosa suggesting that transdermal estrogen may have beneficial effects with respect to bone mineral density in this population.

Bone mineral density at extremely low weight in patients with anorexia nervosa

OBJECTIVE

Low bone mineral density (BMD) is a frequent and invalidating consequence of chronic undernourishment in patients with anorexia nervosa (AN). The aim of this study was to assess prevalence and clinic-biological correlates of low BMD and fractures in extremely undernourished inpatients with AN.

DESIGN

Retrospective cohort study.

PATIENTS AND MEASUREMENTS

This study included 97 extremely malnourished female inpatients with AN consecutively admitted over 2 years. Clinical-biological variables, history of fractures and BMD by dual-energy X-ray absorptiometry (DXA) were examined to find predictors of low BMD and fractures.

RESULTS

The prevalence of low BMD was of 51% for lumbar spine and 38% for femoral neck. Z-scores were lower at lumbar spine (-2.2 ± 1.2 SD) than at femoral neck (-1.9 ± 0.9 SD) (P<.01). Fragility fractures were reported by 10% of patients. BMD was mainly predicted by FFM, illness duration, age at onset and restricting AN (P<.05). Fractures were predicted by sodium concentrations, femoral neck Z-score and illness duration (P<.03).

CONCLUSION

Extremely severe patients with AN have high prevalence of low BMD, predicted by severity and chronicity of malnutrition.

Anorexia nervosa: COVID-19 pandemic period (Review)

Anorexia nervosa is an eating disorder characterized by restrictive eating and an intense fear of gaining weight. It is a disease with an increasing incidence during the last few decades, and represents a complex psychiatric condition which includes secondary amenorrhea, nutritional and metabolic damage, and impaired endocrine panel up to bone loss as well as cardiac, gastrointestinal and hematological complications. This is a narrative review which includes an update on this eating disorder from the perspective of an endocrine panel of anomalies, especially of the skeleton, considering the pressure of the recent global COVID-19 pandemic changes. Practically affecting every organ, anorexia nervosa needs to be taken into consideration during the pandemic period because of the higher risk of relapse due to new living conditions, social distancing, self-isolation, changes in food access, more intense use of social media platforms, disruption of daily habits, and more difficult access to healthcare practitioners. The lack of physical activity in addition to vitamin D deficiency related to low sun exposure or to the use of facial masks may also be connected to further bone damage related to this disease.

Osteoporosis prevention in an extraordinary hibernating bear

Disuse osteoporosis results from physical inactivity. Reduced mechanical loading of bone stimulates bone resorption leading to bone loss, decreased mechanical properties, and increased fracture risk. Compensatory mechanisms evolved in hibernators to preserve skeletal muscle and bone during the prolonged physical inactivity that occurs during annual hibernation. This paper reports the preservation of bone properties in an exceptionally old black bear that was physically inactive for about 6 months annually for 31 years. The biological mechanisms that preserve bone during prolonged disuse during hibernation are also reviewed.

Development of a dual-energy X-ray absorptiometry-derived body volume equation in Hispanic adults for administering a four-compartment model

The purpose of the present study was: (1) to develop a new dual-energy X-ray absorptiometry (DXA)-derived body volume (BV) equation with the GE-Lunar prodigy while utilising underwater weighing (UWW) as a criterion and (2) to cross-validate the novel DXA-derived BV equation (4C-DXANickerson), Wilson DXA-derived BV equation (4C-DXAWilson) and air displacement plethysmography (ADP)-derived BV (4C-ADP) in Hispanic adults. A total of 191 Hispanic adults (18–45 years) participated in the present study. The development sample consisted of 120 females and males (50 % females), whereas the cross-validation sample comprised of forty-one females and thirty males (n 71). Criterion body fat percentage (BF %) and fat-free mass (FFM) were determined using a four-compartment (4C) model with UWW as a criterion for BV (4C-UWW). 4C-DXANickerson, 4C-DXAWilson and 4C-ADP were compared against 4C-UWW in the cross-validation sample. 4C-DXANickerson, 4C-DXAWilson and 4C-ADP all produced similar validity statistics when compared with 4C-UWW in Hispanic males (all P > 0·05). 4C-DXANickerson also yielded similar BF % and FFM values as 4C-UWW when evaluating the mean differences (constant error (CE)) in Hispanic females (CE = –0·79 % and 0·38 kg; P = 0·060 and 0·174, respectively). However, 4C-DXAWilson produced significantly different BF % and FFM values (CE = 3·22 % and –2·20 kg, respectively; both P < 0·001). Additionally, 4C-DXAWilson yielded significant proportional bias when estimating BF % (P < 0·001), whereas 4C-ADP produced significant proportional bias for BF % and FFM (both P < 0·05) when evaluated in Hispanic females. The present study findings demonstrate that 4C-DXANickerson is a valid measure of BV in Hispanics and is recommended for use in clinics, where DXA is the main body composition assessment technique.

Feeding and eating disorders

Eating disorders (EDs) are a group of prevalent psychiatric illnesses with an onset in early to late adolescence-a time of significant neural development, physical and psychologic growth, and self-exploration. The etiology and neurobiology of EDs are not well understood, but EDs are recognized as brain-based illnesses with serious acute and long-term consequences if undertreated or ignored. Two EDs, anorexia nervosa (AN) and bulimia nervosa (BN), have historically been the primary EDs of focus. The DSM-5 updated diagnostic criteria for these disorders added two more: binge-eating disorder (BED) and avoidant/restrictive food intake disorder (ARFID). EDs severely impact males as well as females across the weight spectrum. Comorbidity is high; mortality rates for AN and BN are the highest in psychiatric conditions and higher than many medical conditions. Several treatment options are available to treat an ED ranging from inpatient hospitalization to outpatient services and different psychotherapy options. This chapter reviews the diagnostic criteria, clinical presentation, and treatment for these disorders. Where available, sex differences and developmental considerations will be noted. For all EDs, early recognition and swift treatment are necessary to avoid a chronic course.