Endocrinopathies in children infected with human immunodeficiency virus

Endocrine changes (including adrenal insufficiency, disorders of growth and puberty, thyroid dysfunction, metabolic abnormalities and osteopenia) accompany human immunodeficiency virus (HIV) infection in pediatric patients. The cause of these changes is multifactorial and includes direct viral effects of HIV, and effects of antiretroviral therapy. These effects may be of particular importance in childhood given the critical developmental processes that occur during this time period and the likelihood of prolonged exposure to the virus and medications.

[Gender-specific differences in age-associated endocrinology]

The endocrine system is intimately involved in modulating lifespan and quality of life. Facing an ever increasing proportion of aged people in the western society, there is great interest in understanding the complex interrelations between increasing age and hormonal regulation. Age-associated endocrinological changes comprise the decline of basal hormonal levels, pulsatile hormone distribution, and activity of hormonal axis, which result in changes in body composition. Men and women experience different age-associated alterations of the hormonal system. Aging per se is a risk factor for diseases like diabetes mellitus type 2, thyroid disorders, osteoporosis, frailty, and sarcopenia. Gender-specific differences with respect to symptoms, interactions, diagnosis, and therapy must be taken into consideration. Current data do not allow a general recommendation for hormonal substitution, neither for women nor for men. New research approaches following a multifactorial pathway are required to elucidate the complexity of age-associated endocrinological changes and to develop gender-specific therapies for endocrinological diseases.

[Follow-up and management of children born small for gestational age a endocrine and metabolic aspects]

Children born premature and/or small for gestational age (SGA) are at risk of growth and metabolic abnormalities. Catch-up growth occurs usually before the age of 2. In the absence of sufficient catch up growth, growth hormone (GH) treatment should be evaluated under certain conditions. Children who were born premature and/or SGA are at higher risk of insulin resistance and metabolic abnormalities, especially in case of excessive weight gain during the first months of life. Puberty in these children occurs normally or slightly advanced, with no effect on gonadic function or fertility. Each step of the development of premature and/or SGA children present specific risks, which the pediatrician has to follow. If necessary, the pediatric endocrinologist will initiate a specific management.

The Endocrine Society guidelines: when the confidence cart goes before the evidence horse

CONTEXT

In 2005, the Endocrine Society (TES) adopted the GRADE system of developing clinical practice guidelines. Grading of Recommendations, Assessment, Development, and Evaluation working group guidance suggests that strong recommendations based on low or very low (L/VL) confidence may often be inappropriate, and has offered a taxonomy of paradigmatic situations in which strong recommendations based on L/VL confidence estimates may be appropriate.

OBJECTIVE

We sought to characterize strong recommendations of TES based on L/VL confidence evidence.

DATA SOURCES AND EXTRACTION

We identified all strong recommendations based on L/VL confidence evidence published in TES guidelines between 2005 and 2011. We identified those consistent with one of the paradigmatic situations in the taxonomy.

DATA SYNTHESIS

Two hundred six of 357 (58%) of the recommendations of TES were strong; of these, 121 (59%) were based on L/VL confidence evidence. Of these 121, 35 (29%) were consistent with one of the paradigmatic situations. The most common situation (13, 11%) was of a strong recommendation against the intervention because of low confidence evidence for benefit and high confidence evidence for harm. The remaining 86 (71%) comprised 43 (36%) "best practice" statements for which sensible alternatives do not exist; 5 (4%) in which recommendations were for "additional research"; 5 (4%) in which greater confidence in the estimates was warranted; and 33 (27%) for which we could not find a compelling explanation for the incongruence.

CONCLUSIONS

Guideline panels should beware of formulating strong recommendations when confidence in estimates is low. Our taxonomy when such recommendations are appropriate may be helpful.

[Endocrinometabolic disorders in chronic obstructive pulmonary disease]

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of chronic airflow obstruction and associated endocrinometabolic disorders, which usually worsen the clinic and prognostic of the patients. Therefore, in-depth knowledge of these prevalent disorders in patients with COPD is relevant to develop preventive measures and early detection.

PURPOSE

To analyze the prevalence of endocrinometabolic diseases that occur in COPD subjects and their related risk factors.

METHODS

We carried out a bibliographic search of the bibliographic resources of the last 10 years, including PubMed, Scopus and ScienceDirect databases. Words used were: "endocrine metabolic disorders AND COPD", "endocrine disorders AND COPD" and "metabolic disorders AND COPD". The bibliographical analysis was made in two steps. During the first phase, we excluded those articles in which the title or their content did not correspond with the objective settled; during the second phase, we deleted all the references duplicated in both databases. Finally, 17 articles after full-text critical appraisal were maintained.

RESULTS

After reviewing the articles, we found a significant relationship between diabetes mellitus, metabolic syndrome, obesity, osteoporosis, hypogonadism and COPD. Different authors have reported a higher prevalence of these comorbidities, influencing the development of COPD.

CONCLUSIONS

Due to the high prevalence and association with COPD, these comorbidities have to be considered by the health professionals related to the COPD patients. Better understanding of the endocrinometabolic disorders related to COPD can influence the treatment and the outcome of patients.

Clinical review: kinase inhibitors: adverse effects related to the endocrine system

CONTEXT

The use of kinase inhibitors (KIs) in the treatment of cancer has become increasingly common, and practitioners must be familiar with endocrine-related side effects associated with these agents. This review provides an update to the clinician regarding the management of potential endocrinological effects of KIs.

EVIDENCE ACQUISITION

PubMed was employed to identify relevant manuscripts. A review of the literature was conducted, and data were summarized and incorporated.

EVIDENCE SYNTHESIS

KIs, including small molecule KIs and monoclonal antibodies directed against kinases, have emerged over the past decade as an important class of anticancer agents. KIs specifically interfere with signaling pathways that are dysregulated in certain types of cancers and also target common mechanisms of growth, invasion, metastasis, and angiogenesis. Currently, at least 20 KIs are approved as cancer therapeutics. However, KIs may affect a broad spectrum of targets and may have additional, unidentified mechanisms of action at the cellular level due to overlap between signaling pathways in the tumor cell and endocrine system. Recent reports in the literature have identified side effects associated with KIs, including alterations in thyroid function, bone metabolism, linear growth, gonadal function, fetal development, adrenal function, and glucose metabolism.

CONCLUSIONS

Clinicians need to monitor the thyroid functions of patients on KIs. In addition, bone density and vitamin D status should be assessed. Special care should be taken to follow linear growth and development in children taking these agents. Clinicians should counsel patients appropriately on the potential adverse effects of KIs on fetal development.

Hypothalamic obesity: prevalence, associations and longitudinal trends in weight in a specialist adult neuroendocrine clinic

OBJECTIVE

Obesity is highly prevalent among adults with acquired, structural hypothalamic damage. We aimed to determine hormonal and neuroanatomical variables associated with weight gain and obesity in patients following hypothalamic damage and to evaluate the impact of early instigation of weight loss measures to prevent or limit the severity of obesity in these patients.

DESIGN

Retrospective study of 110 adults with hypothalamic tumours attending a specialist neuroendocrine clinic. BMI was calculated at diagnosis and at last follow-up clinic visit. Endocrine data, procedures, treatments and weight loss measures were recorded and all available brain imaging reviewed.

RESULTS

At last follow-up, 82.7% of patients were overweight or heavier (BMI≥25 kg/m(2)), 57.2% were obese (BMI≥30 kg/m(2)) and 14.5% were morbidly obese (BMI≥40 kg/m(2)). Multivariate analysis revealed that use of desmopressin (odds ratio (OR)=3.5; P=0.026), GH (OR=2.7; P=0.031) and thyroxine (OR=3.0; P=0.03) was associated with development of new or worsened obesity. Neuroimaging features were not associated with weight gain. Despite proactive treatments offered in clinic in recent years (counselling, dietetic and physical activity advice, and anti-obesity medications), patients have continued to gain weight.

CONCLUSIONS

Despite increased awareness, hypothalamic obesity is difficult to prevent and to treat. Improved understanding of the underlying pathophysiologies and multicentre collaboration to examine efficacy of novel obesity interventions are warranted.

Updates in pediatric endocrinology

There are rapid advances being made in the field of medicine! New research continues to investigate etiopathogenic mechanisms underlying many endocrine disorders, new tests to facilitate diagnosis, and newer treatment options. The discussion in this article focuses on a few of the important concerns in adolescent endocrinology and highlights some recent concepts that are important for the physicians taking care of these adolescents. This article also includes a brief update on diabetes mellitus types 1 and 2, obesity, and polycystic ovarian syndrome; new thoughts and controversies about vitamin D and current management of the common thyroid disorders; adrenal insufficiency; and concerns with disorders of puberty in adolescents.

Common endocrine issues in the pediatric intensive care unit

Thyroid hormone is central to normal development and metabolism. Abnormalities in thyroid function in North America often arise from autoimmune diseases, but they rarely present as critical illness. Severe deficiency or excess of thyroid hormone both represent life-threatening disease, which must be treated expeditiously and thoroughly. Such deficiencies must be considered, because presentation may be nonspecific.

A comparative quality assessment of evidence-based clinical guidelines in endocrinology

CONTEXT

Evidence-based clinical guidelines in endocrinology attempt to improve and standardize patient care. There has been an expansion in guideline production although some of the heterogeneous methods used to assess the quality of the underlying evidence base might limit interpretation and implementation.

DESIGN

Current and archived guidelines from major endocrine organizations were accessed. The organizations used six different methods to rate underlying evidence, including Grading of Recommendations Assessment, Development and Evaluation (GRADE). To allow direct comparison between guidelines produced by different organizations, the levels of evidence used to generate them were graded according to the standardized system: 'high' based on randomized, controlled trials and meta-analyses, 'moderate' based on nonrandomized studies and 'low' based on expert opinion.

RESULTS

There was an increase in guideline production over time (1995-2000 = 9, 2001-2005 = 12, 2006-2011 = 36). Three guidelines were updated with an average delay of 4·3 years and an increase in recommendations per guideline (21·1%). Encouragingly, whilst updates had similar levels of 'high'-quality evidence, there was increased reliance on 'moderate'-category evidence and less on 'low''-quality evidence' ('high', 6·3% vs 6·5%; 'moderate', 46·1% vs 59·1%; 'low', 47·7% vs 34·4%). A high proportion of 'low'-category evidence was seen throughout all organizations. Rarer conditions and recommendations concerning treatment efficacy were particularly reliant on 'low'-category evidence.

CONCLUSIONS

The level of evidence underpinning current guidelines highlights areas in need of well-designed, collaborative clinical research. Furthermore, criteria to define when guideline updates are necessary are currently lacking. A standardized method of assessment, such as GRADE, would promote understanding and compliance by guideline users with the ultimate aim of enhancing patient care.

Hypogonadotropic hypogonadism revisited

Impaired testicular function, i.e., hypogonadism, can result from a primary testicular disorder (hypergonadotropic) or occur secondary to hypothalamic-pituitary dysfunction (hypogonadotropic). Hypogonadotropic hypogonadism can be congenital or acquired. Congenital hypogonadotropic hypogonadism is divided into anosmic hypogonadotropic hypogonadism (Kallmann syndrome) and congenital normosmic isolated hypogonadotropic hypogonadism (idiopathic hypogonadotropic hypogonadism). The incidence of congenital hypogonadotropic hypogonadism is approximately 1-10:100,000 live births, and approximately 2/3 and 1/3 of cases are caused by Kallmann syndrome (KS) and idiopathic hypogonadotropic hypogonadism, respectively. Acquired hypogonadotropic hypogonadism can be caused by drugs, infiltrative or infectious pituitary lesions, hyperprolactinemia, encephalic trauma, pituitary/brain radiation, exhausting exercise, abusive alcohol or illicit drug intake, and systemic diseases such as hemochromatosis, sarcoidosis and histiocytosis X. The clinical characteristics of hypogonadotropic hypogonadism are androgen deficiency and a lack/delay/stop of pubertal sexual maturation. Low blood testosterone levels and low pituitary hormone levels confirm the hypogonadotropic hypogonadism diagnosis. A prolonged stimulated intravenous GnRH test can be useful. In Kallmann syndrome, cerebral MRI can show an anomalous morphology or even absence of the olfactory bulb. Therapy for hypogonadotropic hypogonadism depends on the patient's desire for future fertility. Hormone replacement with testosterone is the classic treatment for hypogonadism. Androgen replacement is indicated for men who already have children or have no desire to induce pregnancy, and testosterone therapy is used to reverse the symptoms and signs of hypogonadism. Conversely, GnRH or gonadotropin therapies are the best options for men wishing to have children. Hypogonadotropic hypogonadism is one of the rare conditions in which specific medical treatment can reverse infertility. When an unassisted pregnancy is not achieved, assisted reproductive techniques ranging from intrauterine insemination to in vitro fertilization to the acquisition of viable sperm from the ejaculate or directly from the testes through testicular sperm extraction or testicular microdissection can also be used, depending on the woman's potential for pregnancy and the quality and quantity of the sperm.

[Endocrine abnormalities in HIV-infected patients]

HIV infection is associated with a number of adverse consequences, including endocrine disorders. The endocrine changes associated with HIV infection have been studied in depth and, as the results of so far carried out studies suggest, their aetiology is usually multifactoral. Their pathogenesis includes direct infection of endocrine glands by HIV or opportunistic organisms, infiltration by neoplasms and adverse effects of drugs. Endocrine problems that most frequently affect this group of patients include: hypogonadism, adrenal insufficiency, thyroid disorders, impaired growth hormone release, lipodystrophy and bone loss. They may develop in both the early as well as late stages of the infection, ranging from subclinical disturbances to overt endocrine symptoms. The purpose of this paper is to review the aetiology, clinical manifestations, diagnosis and treatment of HIV-associated endocrine disturbances with a special emphasis on the most recent literature.

[Caring for patients with pediatric endocrinopathies and diabetes into adulthood: challenges of an often difficult transition]

The success of therapies for a number of pediatric disorders has posed new challenges for the long-term follow-up of adolescents with chronic endocrinopathies. Unfortunately, too many patients are lost during the transfer from pediatric to adult clinics. The transition process should be well-organized and include the young person and family. Recognizing the special needs of these adolescents is an important step in developing patient-centered approaches to care that enable patients to develop autonomy and self care skills. Key elements in this process include structured policies and guidelines, communication and close collaboration between pediatric and adult clinics, and integrating nurse clinicians in the transition process to help close the gaps in care.

Health disparities in endocrine disorders: biological, clinical, and nonclinical factors--an Endocrine Society scientific statement

OBJECTIVE

The aim was to provide a scholarly review of the published literature on biological, clinical, and nonclinical contributors to race/ethnic and sex disparities in endocrine disorders and to identify current gaps in knowledge as a focus for future research needs. PARTICIPANTS IN DEVELOPMENT OF SCIENTIFIC STATEMENT: The Endocrine Society's Scientific Statement Task Force (SSTF) selected the leader of the statement development group (S.H.G.). She selected an eight-member writing group with expertise in endocrinology and health disparities, which was approved by the Society. All discussions regarding the scientific statement content occurred via teleconference or written correspondence. No funding was provided to any expert or peer reviewer, and all participants volunteered their time to prepare this Scientific Statement.

EVIDENCE

The primary sources of data on global disease prevalence are from the World Health Organization. A comprehensive literature search of PubMed identified U.S. population-based studies. Search strategies combining Medical Subject Headings terms and keyword terms and phrases defined two concepts: 1) racial, ethnic, and sex differences including specific populations; and 2) the specific endocrine disorder or condition. The search identified systematic reviews, meta-analyses, large cohort and population-based studies, and original studies focusing on the prevalence and determinants of disparities in endocrine disorders. consensus process: The writing group focused on population differences in the highly prevalent endocrine diseases of type 2 diabetes mellitus and related conditions (prediabetes and diabetic complications), gestational diabetes, metabolic syndrome with a focus on obesity and dyslipidemia, thyroid disorders, osteoporosis, and vitamin D deficiency. Authors reviewed and synthesized evidence in their areas of expertise. The final statement incorporated responses to several levels of review: 1) comments of the SSTF and the Advocacy and Public Outreach Core Committee; and 2) suggestions offered by the Council and members of The Endocrine Society.

CONCLUSIONS

Several themes emerged in the statement, including a need for basic science, population-based, translational and health services studies to explore underlying mechanisms contributing to endocrine health disparities. Compared to non-Hispanic whites, non-Hispanic blacks have worse outcomes and higher mortality from certain disorders despite having a lower (e.g. macrovascular complications of diabetes mellitus and osteoporotic fractures) or similar (e.g. thyroid cancer) incidence of these disorders. Obesity is an important contributor to diabetes risk in minority populations and to sex disparities in thyroid cancer, suggesting that population interventions targeting weight loss may favorably impact a number of endocrine disorders. There are important implications regarding the definition of obesity in different race/ethnic groups, including potential underestimation of disease risk in Asian-Americans and overestimation in non-Hispanic black women. Ethnic-specific cut-points for central obesity should be determined so that clinicians can adequately assess metabolic risk. There is little evidence that genetic differences contribute significantly to race/ethnic disparities in the endocrine disorders examined. Multilevel interventions have reduced disparities in diabetes care, and these successes can be modeled to design similar interventions for other endocrine diseases.

Mechanisms in endocrinology: micro-RNAs: targets for enhancing osteoblast differentiation and bone formation

Osteoblast differentiation and bone formation (osteogenesis) are regulated by transcriptional and post-transcriptional mechanisms. Recently, a novel class of regulatory factors termed micro-RNAs (miRNAs) has been identified as playing an important role in the regulation of many aspects of osteoblast biology including proliferation, differentiation, metabolism and apoptosis. Also, preliminary data from animal disease models suggest that targeting miRNAs in bone can be a novel approach to increase bone mass. This review highlights the current knowledge of miRNA biology and their role in bone formation and discusses their potential use in future therapeutic applications for metabolic bone diseases.

[Diabetes and prediabetes in endocrine disorders]

Complex hormonal regulation of carbohydrate metabolism causes that presence of many endocrine disorders may disturb glucose homeostasis. Impaired fasting glucose, impaired glucose tolerance and frank diabetes are observed in patients with both common and rare endocrine disorders, particularly in patients with polycystic ovary syndrome, hyperthyroidism, Cushing's syndrome, pheochromocytoma, primary aldosteronism, acromegaly, growth hormone deficiency and endocrine tumors of the digestive system. Because most of these disorders may be effectively treated and the treatment often results in a restoration of normal insulin secretion and receptor action as well as glucose absorption, production and metabolism, it is important to differentiate these disorders from other more common types of diabetes. This article reviews the etiology, clinical manifestation, diagnosis and management of endocrine disorders leading to diabetes and prediabetic states with special emphasis on the pathogenesis and clinical consequences of these disorders.

[Transcranial physical methods for correction of neuroendocrine and cerebral disorders in adolescent girls with obesity]

AIM

To evaluate the efficiency of combined central and local physiotherapeutic procedures in correcting neuroendocrine and menstrual disorders in pubertal girls (PG) with obesity.

SUBJECTS AND METHODS

Eighty-seven PGs, including 67 with different levels of obesity and 20 healthy non-obese girls, were examined. The hormonal profile, lipidogram, and fasting insulin and glucose levels were studied. Body mass index (BMI) and waist and hip circumferences were estimated. The functional state of the central nervous system was studied by electroencephalography. The parameters of the autonomic nervous system were estimated by cardiointervalography. The PGs with obesity were divided into 2 groups: a study group (SG) (n = 40) and a control group (CG) (n = 27). The healthy PGs (n = 20) formed a comparison group. The SG patients received bitemporal transcranial magnetic therapy in combination with frontomastoid transcranial electrostimulation, as well as myoelectrostimulation of the anterior abdominal wall, by transferring the area of stimulation from right to left hypochondrium. A course consisted of 10-15 daily sessions. CG had placebo physioprocedures (with disconnected electrodes).

RESULTS

After 6-month treatment, SG and CG showed average reductions in BMI by 5.9 and 2.5 kg/m2, respectively. Lipidograms normalized in 70%; menstrual cycles were restored in 25 of 30 patients with impaired cycles in SG and in 1 of 22 in CG. Hormonal profiles were significantly improved in 62.5% of the patients in SG and unchanged in CG.

CONCLUSION

The high efficiency of combined (central and local) physiotherapeutic procedures is likely to be dueto the normalization of pituitary-ovarian relationships and enables one to recommend the proposed procedure in a rehabilitation program for PGs with obesity and reproductive system disorders.

Overview of the endocrine response to critical illness: how to measure it and when to treat

The assessment and manipulation of the endocrine system in patients with critical illness is one of the most complex and controversial areas in endocrinology. Severe acute illness causes dramatic changes in most endocrine systems. This can lead to considerable difficulty in recognising pre-existing endocrine disorders in severely ill patients. Critical care itself might also induce types of endocrine dysfunction not seen outside the critical care unit. It is important to clarify whether or not such endocrine dysfunction occurs. Where it does occur it is also important to determine whether endocrine intervention is useful in improving outcome. There is also the issue of whether endocrine manipulation in critically ill patients without endocrine dysfunction could benefit from endocrine intervention, e.g. to improve haemodynamics or reverse a catabolic state. This review will discuss some of these contentious issues. It will highlight how endocrine assessment of a patient with critical illness differs from that in other types of patient. It will emphasise the added need to place the biochemical assessment and its interpretation in the context of the patients underlying condition.

Recent consensus statements in pediatric endocrinology: a selective review

Clinical guidelines and consensus statements serve to summarize and organize current knowledge on diverse subjects and provide practical guidelines for proper clinical management. Recommendations should be based on research and evidence derived from appropriate sources. In 2008, more than 20 consensus statements were published in the pediatric literature alone. This article summarizes the salient points of the latest consensus statements jointly developed by multiple endocrine societies including the Lawson Wilkins Society for Pediatric Endocrinology and the European Society for Pediatric Endocrinology. As much as possible, the original intent and language of the statements was respected and paraphrased.

Endocrine hypertension--current understanding and comprehensive management review

Hypertension is a very common disease, leading to significant morbidity with reduction in quality of life. In addition to being a major cause of morbidity and mortality, hypertension places a heavy burden on health care systems, families, and society as a whole. In patients with hypertension, the ability to identify a contributing or secondary cause that is potentially curable or amenable to specific forms of management is of great importance. Endocrine hypertension has emerged as one of the common forms of secondary hypertension. Primary aldosteronism, pheochromocytoma and Cushing's syndrome are among the common causes of endocrine hypertension. The application of new clinical, biochemical, and radiologic approaches has significantly advanced our understanding of the pathophysiology and clinical spectrum of these diseases and improved the management strategies of these challenging conditions.

The metabolic syndrome in critically ill patients

Metabolic support in intensive care is a rapidly evolving field with new information being gathered almost on a daily basis. In endocrine practice, over the last 20 years, researchers have focussed on a new entity, termed the "metabolic syndrome". This describes the constellation of abnormalities which include central adiposity, insulin resistance and inflammation. All of these predispose the individual to a greater risk of cardiovascular events. Of interest is the observation that some of the metabolic abnormalities in sepsis and multiple organ dysfunction syndrome of critical illness share several common features with that of the metabolic syndrome. In this chapter we describe the features of the metabolic syndrome as is understood in endocrine parlance, the metabolic abnormalities of critical illness and explore the common threads underlying the pathophysiology and the treatment of the two syndromes. The role of adiponectin in the metabolic abnormalities in both the metabolic syndrome and in sepsis are reviewed. The potential role of the pleiotropic effects of statins in the therapy of sepsis is also discussed.

Canadian Consensus Conference on menopause, 2006 update

OBJECTIVE

To provide guidelines for health care providers on the management of menopause in asymptomatic healthy women as well as in women presenting with vasomotor symptoms, urogenital, sexual, and mood and memory concerns and on specific medical considerations, and cardiovascular and cancer issues.

OUTCOMES

Prescription medications, complementary and alternative medicine (CAM), and lifestyle interventions are presented according to their efficacy in treating menopausal symptoms.

EVIDENCE

MEDLINE and the Cochrane database were searched for articles from March 2001 to April 2005 in English on subjects related to menopause, menopausal symptoms, urogenital and sexual health, mood and memory, hormone therapy, CAM, and on specific medical considerations that affect the decision of which intervention to choose.

VALUES

The quality of evidence is rated using the criteria described in the report of the Canadian Task Force on the Periodic Health Examination. Recommendations for practice are ranked according to the method described in this report (see Table 1).

SPONSORS

The development of this consensus guideline was supported by unrestricted educational grants from Berlex Canada Inc, Lilly Canada, Merck Frosst, Novartis, Novogen, Novo Nordisk, Proctor and Gamble, Schering Canada, and Wyeth Canada.

An endocrinologist's guide to the clock

CONTEXT

It has long been recognized that a "biological clock" residing in the suprachiasmatic nucleus controls circadian or daily variations in physiological processes. Old observations are now being revisited after the discovery of the cellular mechanism of timekeeping, the molecular clock, an autoregulatory feedback loop of transcription factors that cycles over a period of approximately 24 h. Its functioning or breakdown impinges upon the physiology and pathophysiology of numerous systems, including the endocrine system and metabolism. Here we provide an introduction to those aspects of the clock most relevant to the endocrinologist.

EVIDENCE ACQUISITION

Articles were identified by searching PubMed using the search terms "circadian" and "clock" and refining results to include articles relating to endocrinology and metabolism.

EVIDENCE SYNTHESIS

We discuss current understanding of the mechanisms through which hormonal and metabolic axes fall under the influence of the circadian clock. Of particular interest is the complex interaction of genetic and environmental factors in determining health or disease states.

CONCLUSIONS

Research into the molecular clock provides a novel window onto endocrine and metabolic disease. These advances present new avenues for diagnostic and therapeutic strategies.

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.