Optimizing bone health in anorexia nervosa and hypothalamic amenorrhea: new trials and tribulations

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.

Menstrual disorders in adolescents and young adults with eating disorders

Although amenorrhea is no longer a specific criterion required to make the diagnosis of anorexia nervosa (AN), the relationship between restrictive eating and menstrual status remains important in the diagnosis, treatment, and consequences for patients with eating disorders. Clinicians should understand the relationship between menstrual irregularities and malnutrition due to eating disorders, as it may be possible to intervene sooner if the diagnosis is made earlier. Treatment of AN (in those who are underweight) and atypical AN (in those who are not underweight) is aimed at cessation of restrictive thoughts and behaviors, restoration of appropriate nutrition and weight, and normal functioning of the body. While eating disorder thoughts and behaviors are helped by both therapy and nutrition, regular functioning of the body, including regular menstruation, is linked to both appropriate nutrition and weight. Patients who are not underweight based on their body mass index (BMI) may still have oligo/amenorrhea due to their caloric restriction; thus any patient who has irregular menses should have a detailed dietary evaluation as part of their workup. Timely diagnosis and treatment of patients with eating disorders and amenorrhea is important due to the impact on bone mass accrual for adolescents who have prolonged amenorrhea. Menstrual abnormalities may also be seen in patients with bulimia nervosa (BN).

The effect of underweight on female and male reproduction

Chronic energy deficiency can impair the hypothalamic-pituitary-gonadal (HPG) axis and lead to hypothalamic anovulation in underweight women. This review presents the syndromes related to underweight status that are associated with infertility, summarizes the underlying mechanisms, and reviews the available treatment options. Eating disorders, such as anorexia nervosa (AN), constitute the most common cause of infertility in underweight women, who, in addition, experience miscarriages, and sexual dysfunction. The relative energy deficiency in sports (RED-S; former terminology: athlete's triad) involves menstrual dysfunction due to low energy availability, which results in anovulation. Moreover, lipodystrophies, malnutrition, starvation, systematic illnesses (malignancies, endocrinopathies, infectious diseases, advanced chronic diseases, neurologic illnesses), and the utilization of drugs can cause excessive weight loss. They may result in fertility problems due to the loss of adipose tissue and the subsequent hormonal disturbances. Each of these conditions requires multidisciplinary management. Nutritional counseling should target the restoration of energy balance by increasing intake and reducing output. Medical treatment, recommended only for patients who did not respond to standard treatment, may include antipsychotics, antidepressants, or leptin administration. Finally, psychiatric treatment is considered an integral part of the standard treatment.

Decreased bone mineral density in women with Sheehan's syndrome and improvement following oestrogen replacement and nutritional supplementation

Sheehan's syndrome (SS) is an important cause of pan-hypopituitarism in women. There is scanty information on bone mineral density (BMD) in this condition. We determined BMD and the changes in BMD after oestrogen (E2) replacement and nutritional supplementation in women with SS. In a cross-sectional study, BMD was measured by DEXA in 83 patients [age (mean ± SD) 42 ± 9.2 years] and compared with an equal number of matched controls. In a sub-set of 19 patients, we conducted an open-label, prospective study to determine changes in BMD after 1 year of replacement of E2, and calcium and vitamin D3 supplementation. All patients had low serum IGF-1 and E2, while 98% had ≥ 3 pituitary hormone deficiencies. Compared with Indian reference standards, 47% had decreased bone mass (Z-score ≤ - 2.0). BMD Z-scores were decreased at all sites, being most marked in the lumbar spine and femoral neck. At the lumbar spine, BMD was lowest among the age group 21-30 years. Women with SS also had significantly lower BMD Z-scores at all three sites on comparison with ethnic controls. On multivariate analysis, BMD Z-score was associated with weight, daily calcium intake and age (lumbar spine). In the prospective study, 1 year of therapy improved BMD Z-score at lumbar spine (- 1.4 ± 1.2 vs. - 1.1 ± 1.1, p = 0.02), but not at hip or femoral neck. In conclusion, patients with SS had significantly lower BMD compared to controls at all three sites. Replacement of E2 and supplementation with calcium/vitamin D3 lead to significant improvement in lumbar spine BMD.

Leptin applications in 2015: what have we learned about leptin and obesity?

PURPOSE OF REVIEW

To summarize previous and current advancements for leptin therapeutics, we described how leptin may be useful in leptin deficient states such as lipodystrophy, for which leptin was recently approved, and how it may be useful in the future for typical obesity.

RECENT FINDINGS

The discovery of leptin in 1994 built the foundation for understanding the pathophysiology and treatment of obesity. Leptin therapy reverses morbid obesity related to congenital leptin deficiency and appears to possibly treat lipodystrophy, a finding which has led to the approval of leptin for the treatment of lipodystrophy in the USA and Japan. Typical obesity, on the other hand, is characterized by hyperleptinemia and leptin tolerance. Thus, leptin administration has proven ineffective for inducing weight loss on its own but could possibly be useful in combination with other therapies or for weight loss maintenance.

SUMMARY

Leptin is not able to treat typical obesity; however, it is effective for reversing leptin deficiency-induced obesity and is possibly useful in lipodystrophy. New mechanisms and pathways involved in leptin resistance are continuously discovered, whereas the development of new techniques and drug combinations which may improve leptin's efficacy and safety regenerate the hope for its use as an effective treatment for typical obesity.

Cancer Incidence among Patients with Anorexia Nervosa from Sweden, Denmark and Finland

A diet with restricted energy content reduces the occurrence of cancer in animal experiments. It is not known if the underlying mechanism also exists in human beings. To determine whether cancer incidence is reduced among patients with anorexia nervosa who tend to have a low intake of energy, we carried out a retrospective cohort study of 22 654 women and 1678 men diagnosed with anorexia nervosa at ages 10-50 years during 1968-2010 according to National Hospital Registers in Sweden, Denmark and Finland. The comparison group consisted of randomly selected persons from population registers who were similar to the anorexia nervosa patients in respect to sex, year of birth and place of residence. Patients and population comparisons were followed for cancer by linkage to Cancer Registries. Incidence rate ratios (IRR) were estimated using Poisson models. In total, 366 cases of cancer (excluding non-melanoma skin cancer) were seen among women with anorexia nervosa, and the IRR for all cancer sites was 0.97 (95% CI = 0.87-1.08) adjusted for age, parity and age at first child. There were 76 breast cancers corresponding to an adjusted IRR of 0.61 (95% CI = 0.49-0.77). Significantly increased IRRs were observed for esophageal, lung, and liver cancer. Among men with anorexia nervosa, there were 23 cases of cancer (age-adjusted IRR = 1.08; 95% CI = 0.71-1.66). There seems to be no general reduction in cancer occurrence among patients with anorexia nervosa, giving little support to the energy restriction hypothesis.

The role of leptin in regulating bone metabolism

Leptin was initially best known for its role in energy homeostasis and regulation of energy expenditure. In the past few years we have realized that leptin also plays a major role in neuroendocrine regulation and bone metabolism. Here, we review the literature the indirect and direct pathways through which leptin acts to influence bone metabolism and discuss bone abnormalities related to leptin deficiency in both animal and human studies. The clinical utility of leptin in leptin deficient individuals and its potential to improve metabolic bone disease are also discussed. We are beginning to understand the critical role leptin plays in bone metabolism; future randomized studies are needed to fully assess the potential and risk-benefit of leptin's use in metabolic bone disease particularly in leptin deficient individuals.

Leptin and the brain: influences on brain development, cognitive functioning and psychiatric disorders

Receptors of leptin, the prototypical adipokine, are expressed throughout the cortex and several other areas of the brain. Although typically studied for its role in energy intake and expenditure, leptin plays a critical role in many other neurocognitive processes and interacts with various other hormones and neurotransmitters to perform these functions. Here, we review the literature on how leptin influences brain development, neural degradation, Alzheimer's disease, psychiatric disorders, and more complicated cognitive functioning and feeding behaviors. We also discuss modulators of leptin and the leptin receptor as they relate to normal cognitive functioning and may mediate some of the actions of leptin in the brain. Although we are beginning to better understand the critical role leptin plays in normal cognitive functioning, there is much to be discovered.

The effect of leptin replacement on parathyroid hormone, RANKL-osteoprotegerin axis, and Wnt inhibitors in young women with hypothalamic amenorrhea

CONTEXT

Recombinant leptin (metreleptin) treatment restores bone mineral density in women with hypothalamic amenorrhea (HA), a condition characterized by hypoleptinemia, which has adverse impact on bone health.

OBJECTIVE

The objective of the study was to investigate how metreleptin exerts its positive effect on bone metabolism in humans.

DESIGN

This was a randomized, double-blinded, placebo-controlled study.

SETTING

The study was conducted at Beth Israel Deaconess Medical Center (Boston, Massachusetts).

PATIENTS AND INTERVENTIONS

Women (n = 18) with HA and hypoleptinemia for at least 6 months were randomized to receive either metreleptin or placebo for 36 weeks. Serum samples were obtained at baseline and 12, 24, and 36 weeks of treatment.

MAIN OUTCOME MEASURES

Circulating levels of leptin, intact PTH (iPTH), receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), sclerostin, dickkopf-1, and fibroblast growth factor-23.

RESULTS

Metreleptin administration significantly increased leptin levels throughout the treatment period (P = .001). iPTH decreased over the 36 weeks of treatment (P = .01). There was a trend toward a decrease in serum RANKL and increase in serum OPG in the metreleptin-treated group. The RANKL to OPG ratio was significantly decreased within the metreleptin (P = .04) but not the placebo group. Metreleptin had no effect on serum sclerostin, dickkopf-1, and fibroblast growth factor-23.

CONCLUSIONS

Metreleptin treatment over 36 weeks decreases iPTH and RANKL to OPG ratio levels in hypoleptinemic women with HA.