Eating disorders in adolescence: what is the role of hormone replacement therapy?

The ability of low-magnitude mechanical signals to normalize bone turnover in adolescents hospitalized for anorexia nervosa

We sought to determine whether low-magnitude mechanical stimulation (LMMS) normalizes bone turnover among adolescents hospitalized for anorexia nervosa (AN). Brief, daily LMMS prevents the decline in bone turnover typically seen during bed rest in AN. LMMS may have application for patients with AN in the inpatient setting to protect bone health.

INTRODUCTION

Malnourished adolescents with AN requiring medical hospitalization are at high risk for rapid reduction in skeletal quality. Even short-term bed rest can suppress normal patterns of bone turnover. We sought to determine whether LMMS normalizes bone turnover among adolescents hospitalized for complications of AN.

METHODS

In this randomized, double-blind trial, we prospectively enrolled adolescent females (n = 41) with AN, age 16.3 ± 1.9 years (mean ± SD) and BMI 15.6 ± 1.7 kg/m². Participants were randomized to stand on a platform delivering LMMS (0.3 g at 32-37 Hz) or placebo platform for 10 min/day for 5 days. Serum markers of bone formation [bone-specific alkaline phosphatase (BSAP)], turnover [osteocalcin (OC)], and bone resorption [serum C-telopeptides (CTx)] were measured. From a random coefficients model, we constructed estimates and confidence intervals for all outcomes.

RESULTS

BSAP decreased by 2.8% per day in the placebo arm (p = 0.03) but remained stable in the LMMS group (p = 0.51, p_diff = 0.04). CTx did not change with placebo (p = 0.56) but increased in the LMMS arm (+6.2% per day, p = 0.04; p_diff = 0.01). Serum OC did not change in either group (p > 0.70).

CONCLUSIONS

Bed rest during hospitalization for patients with AN is associated with a suppression of bone turnover, which may contribute to diminished bone quality. Brief, daily LMMS prevents a decline in bone turnover during bed rest in AN. Protocols prescribing strict bed rest may not be appropriate for protecting bone health for these patients. LMMS may have application for these patients in the inpatient setting.

Bone health in eating disorders

Eating disorders (EDs) put adolescents and young adults at risk for impaired bone health. Low bone mineral density (BMD) with ED is caused by failure to accrue peak bone mass in adolescence and bone loss in young adulthood. Although ED patients diagnosed with bone loss may be asymptomatic, some suffer bone pains and have increased incidence of fractures. Adolescents with ED are prone to increased prevalence of stress fractures, kyphoscoliosis and height loss. The clinical picture of the various EDs involves endocrinopathies that contribute to impaired bone health. Anorexia nervosa (AN) is characterized by low bone turnover, with relatively higher osteoclastic (bone resorptive) than osteoblastic (bone formation) activity. Bone loss in AN occurs in both the trabecular and cortical bones, although the former is more vulnerable. Bone loss in AN has been shown to be influenced by malnutrition and low weight, reduced fat mass, oestrogen and androgen deficiency, glucocorticoid excess, impaired growth hormone-insulin-like growth factor 1 axis, and more. Bone loss in AN may not be completely reversible despite recovery from the illness. Treatment modalities involving hormonal therapies have limited effectiveness, whereas increased caloric intake, weight gain and resumption of menses are essential to improved BMD.

Gene receptor polymorphism as a risk factor for BMD deterioration in adolescent girls with anorexia nervosa

Anorexia nervosa is a serious eating disorder that is associated with decreased bone mineral density and greater lifetime risk for fractures. This case-controlled study, analyzed single nucleotide polymorphisms of genes encoding vitamin D receptor, estrogen receptor alpha (ESR1), collagen type I and calcitonin receptor (CTR). Relationships between genotype and body mass index, cycling status and lumbar spine bone mineral density (LBMD) were determined in 40 adolescent girls with anorexia nervosa and 10 age-matched controls. The distribution of CTR-AluI genotypes differed between groups, but this polymorphism was not associated with LBMD Z-score. Distribution of ESR1-XbaI genotypes did not differ between groups, but the AA genotype was associated with decreased LBMD Z-score (≤-1) (OR = 24.79, 95% CI, 1.01-606.08). Carriers of the A allele were more likely to have decreased LBMD Z-scores compared with carriers of the G allele (OR = 4.12, 95% CI, 1.23-13.85, p = 0.022). In conclusion, our study shows that anorexic patients with wild-type genotype ESR-XbaI receptor are in greater risk for decreased BMD in relation to those with the mutated gene. Prompt recognition of these patients is crucial because early administration of the proper therapeutic treatment may contribute to the prevention of adverse sequelae on bone metabolism.

Assessment of anorexia nervosa in children and adolescents

Anorexia nervosa is a debilitating illness that affects mostly females and their families. Multiple physiologic disturbances are present and can be life-threatening. Nutritional rehabilitation is the foremost initial treatment goal. Assessment skills include understanding the physiologic, developmental, and psychiatric status of the individual as well as engagement of the family system. A comprehensive assessment that stimulates patient and family to successfully engage in treatment is the cornerstone of good clinical care for this highly disabling disorder.

Endocrine manifestations of eating disorders

CONTEXT

The endocrinopathies associated with eating disorders involve multiple systems and mechanisms designed to preserve energy and protect essential organs. Those systems that are most affected are in need of significant energy, such as the reproductive and skeletal systems. The changes in neuropeptides and in the hypothalamic axis that mediate these changes also receive input from neuroendocrine signals sensitive to satiety and food intake and in turn may be poised to provide significant energy conservation. These adaptive changes are described, including the thyroid, GH, and cortisol axes, as well as the gastrointestinal tract.

EVIDENCE ACQUISITION

Articles were found via PubMed search for both original articles and reviews summarizing current understanding of the endocrine changes of eating disorders based on peer review publications on the topic between 1974 and 2009.

CONCLUSION

The signals that control weight and food intake are complex and probably involve multiple pathways that appear to have as a central control the hypothalamus, in particular the medial central area. The hypothalamic dysfunction of eating disorders provides a reversible experiment of nature that gives insight into understanding the role of various neuropeptides signaling nutritional status, feeding behavior, skeletal repair, and reproductive function.

Anorexia nervosa: a psychiatric illness with gynecological manifestations. A survey of knowledge and practice among Greek gynecologists

OBJECTIVE

Anorexia nervosa (AN) affects a large number of women, usually in their adolescence. One of the primary manifestations of the disease is menstrual irregularity, and the presence of a menstrual cycle is often used as a sign of recovery among patients. Women with AN are likely to seek medical advice from a gynecologist with regards to their period problems. The role of the gynecologist is therefore crucial in identifying and referring these patients promptly to specialised centers.

STUDY DESIGN

A brief anonymous questionnaire was completed by 94 gynecologists practising in Athens.

RESULTS

Approximately half of the responders felt that the conditions were rarer than it really is, and 25% thought that the disease primarily affects women in their early twenties. Although 56% of gynecologists would not prescribe the combined oral contraceptive in women with AN in order to restore their periods, the remainder of gynecologists were in favour of prescribing hormone replacement with a view to reducing the risk of osteopenia. This is despite the fact that emerging evidence shows there is no benefit. Ten percent of gynecologists never weigh their patients during evaluation of amenorrhoea and 72% felt that their level of knowledge as far as anorexia nervosa is concerned is inadequate.

CONCLUSION

More education is required among gynecologists on the subject of anorexia nervosa, in order to identify and refer patients in the early stages of the disease process.

Bone marrow changes in adolescent girls with anorexia nervosa

Early osteoporosis is common among adolescent girls with anorexia nervosa (AN) and may result from premature conversion of red (RM) to yellow bone marrow. We performed right knee magnetic resonance imaging (MRI) on a 1.0 T extremity scanner in 20 patients and 20 healthy controls, aged 16.2 +/- 1.6 years (mean +/- SD). Coronal T(1)-weighted (T(1)W) images and T(1) maps were generated from T(1) relaxometry images. Blinded radiologists visually assessed RM in the distal femoral and proximal tibial metaphyses in T(1)W images using a scale of signal intensity from 0 (homogeneous hyperintensity, no RM) to 4 (all dark, complete RM). Subjects with AN exhibited nearly twofold lower metaphyseal RM scores in both the femur (0.64 versus 1.22, p = .03) and tibia (0.54 versus 0.96, p = .08). In relaxometric measurements of four selected regions (femur and tibia amd epiphysis and metaphysis), subjects with AN showed higher mean epiphyseal but lower metaphyseal T(1). The net AN-control difference between epiphysis and metaphysis was 70 ms in the femur (+31 versus -35 ms, p = .02) and of smaller magnitude in the tibia. In relaxometry data from the full width of the femur adjacent to the growth plate, AN subjects showed mean T(1) consistently lower than in controls by 30 to 50 ms in virtually every part of the sampling region. These findings suggest that adolescents with AN exhibit premature conversion of hematopoietic to fat cells in the marrow of the peripheral skeleton potentially owing to adipocyte over osteoblast differentiation in the mesenchymal stem cell pool.

The effect of bed rest on bone turnover in young women hospitalized for anorexia nervosa: a pilot study

CONTEXT

Malnourished adolescents with anorexia nervosa (AN) requiring medical hospitalization are at high risk for skeletal insults. Even short-term bed rest may further disrupt normal patterns of bone turnover.

OBJECTIVE

The objective of the study was to determine the effect of relative immobilization on bone turnover in adolescents hospitalized for AN.

DESIGN

This was a short-term observational study.

SETTING

The study was conducted at a tertiary care pediatric hospital.

STUDY PARTICIPANTS

Twenty-eight adolescents with AN, aged 13-21 yr with a mean body mass index of 15.9 +/- 1.8 kg/m(2), were enrolled prospectively on admission.

INTERVENTION

As per standard care, all subjects were placed on bed rest and graded nutritional therapy.

MAIN OUTCOME MEASURE

Markers of bone formation (bone specific alkaline phosphatase), turnover (osteocalcin), and bone resorption (urinary N-telopeptides NTx) were measured.

RESULTS

During the 5 d of hospitalization, serum osteocalcin increased by 0.24 +/- 0.1 ng/ml . d (P = 0.02). Urine N-telopeptides reached a nadir on d 3, declining -6.9 +/- 2.8 nm bone collagen equivalent per millimole creatinine (P = 0.01) but returned to baseline by d 5 (P > 0.05). Bone-specific alkaline phosphatase exhibited a decline that was strongly age dependent, being highly significant for younger subjects only [age 14 yr: -0.42 +/- 0.11 (P = 0.0002); age 18 yr: -0.03 +/- 0.08 (P = 0.68)]. Age had no effect on other outcome measures.

CONCLUSION

Limitation of physical activity during hospitalization for patients with AN is associated with suppressed bone formation and resorption and an imbalance of bone turnover. Future interventional studies involving mechanical stimulation and/or weight-bearing activity are needed to determine whether medical protocols prescribing strict bed rest are appropriate.