Low serum triiodothyronine in patients with anorexia nervosa

Are menstrual disturbances associated with an energy availability threshold? A critical review of the evidence

Exercising women have a high prevalence of menstrual disturbances. In 2003, it was suggested that disruption in luteinizing hormone (LH) pulsatility occurs below a threshold of energy availability (EA) of 30 kcal/kg lean body mass (LBM)/day. This paper is a critical review of the evidence regarding the theory that disruptions to the reproductive axis and menstrual disturbances occur below the proposed threshold. Short-term laboratory studies demonstrated that 4-5 days of an EA below 30 kcal/kg LBM/day, induced with or without exercise, decreased serum triiodothyronine and LH pulse frequency, and increased LH pulse amplitude in sedentary, regularly menstruating women. Fewer studies have investigated downstream ovarian effects after long-term exposure to low EA. The Sargent Camp Study was the first randomized trial that induced luteal phase defects, delayed menses, and anovulation by causing weight loss (-4 ± 0.3 kg) with an abrupt increase in exercise volume for two menstrual cycles. The BioEnergetics Study was a randomized controlled trial that induced varying levels of energy deficits by manipulating energy intake and expenditure for three menstrual cycles. LH pulse frequency and triiodothyronine decreased, and 57% of women developed luteal phase defects, anovulation, and/or oligomenorrhea. An EA below 30 kcal/kg fat free mass/day increased the chance of experiencing a menstrual disturbance by 50%. However, menstrual disturbances were observed above and below that EA threshold, and changes in LH pulse frequency predicted only luteal phase defects, not oligomenorrhea or anovulation. The proposed EA threshold is not a cut-off below which menstrual disturbances occur, but represents an increased risk of experiencing menstrual disturbances.

Structure-function relationship of the pituitary gland in anorexia nervosa and intense physical activity

Patients with Anorexia Nervosa (AN) and athletes share intense physical activity and pituitary hormonal disturbances related to absolute (AN) or relative (athletes) undernutrition. Pituitary gland (PG) structure evaluations in those conditions are scarce, and did not differentiate anterior from posterior lobe. We evaluated the structure-function relationship of anterior and posterior PG in AN and athletes, and potential reversibility of this alteration in a group of weight-recovered patients (AN_Rec). Manual delineation of anterior (AP) and posterior (PP) PG was performed on T1-weighted MR images in 17 women with AN, 15 women with AN_Rec, 18 athletes women and 25 female controls. Anthropometric, hormonal, and psychometric parameters were explored and correlated with PG volumes. AP volume (APV) was lower in AN (448 ± 82 mm3), AN_Rec (505 ± 59 mm3), and athletes (540 ± 101 mm3) vs. Controls (615 ± 61 mm3, p < 0.00001, p < 0.00001 and p = 0.02, respectively); and smaller in AN vs. AN_Rec (p = 0.007). PP volume did not show any differences between the groups. APV was positively correlated with weight (R = 0.36, p = 0.011) in AN, and luteinizing hormone (R = 0.35, p = 0.014) in total group. In AN, mean growth hormone (GH) was negatively correlated with global pituitary volume (R = 0.31, p = 0.031) and APV (R = 0.29, p = 0.037). Absolute and relative undernutrition led to a decreased anterior pituitary gland volume, which was reversible with weight gain, correlated with low bodyweight, and blockade of gonadal hypothalamic-pituitary axis. Intriguing inverse correlation between anterior pituitary gland volume and GH plasma level could suggests a low storage capacity of anterior pituitary gland and increased reactivity to low insulin-like growth factor type 1.

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.

The Pathophysiology of Anorexia Nervosa in Hypothalamic Endocrine Function and Bone Metabolism

Anorexia nervosa (AN) is a persistent psychiatric disorder that is marked by abnormal reduced weight and amenorrhea, which may be primary or secondary. AN affects multiple endocrine axes such as gonadal, thyroid, and adrenal axis, growth hormone, and insulin-like growth factor-1, adipokines such as leptin, gut peptides like ghrelin, peptide YY, and amylin. As a result of these changes bone mineral density is reduced, which increases the risk of bone fracture in patients. In this review, we focus on substantial endocrine alterations in AN with a particular emphasis on the severe bone loss associated with this condition and current bone therapies. The disorder primarily affects girls and women, who are the focus of this review. Although the majority of AN-related endocrinopathies improve over time, long-term consequences such as short stature, osteoporosis, and infertility may occur. To avoid serious consequences, nutrition therapy in these patients requires a full understanding of bone complications, and new therapeutic options for treatment should be researched.

Nonthyroidal illness syndrome (NTIS) in severe COVID-19 patients: role of T3 on the Na/K pump gene expression and on hydroelectrolytic equilibrium

Background

Nonthyroidal Illness Syndrome (NTIS) can be detected in many critical illnesses. Recently, we demonstrated that this condition is frequently observed in COVID-19 patients too and it is correlated with the severity the disease. However, the exact mechanism through which thyroid hormones influence the course of COVID-19, as well as that of many other critical illnesses, is not clear yet and treatment with T4, T3 or a combination of both is still controversial. Aim of this study was to analyze body composition in COVID-19 patients in search of possible correlation with the thyroid function.

Methods and findings

We report here our experience performed in 74 critically ill COVID-19 patients hospitalized in the intensive care unit (ICU) of our University Hospital in Rome. In these patients, we evaluated the thyroid hormone function and body composition by Bioelectrical Impedance Analysis (BIA) during the acute phase of the disease at admission in the ICU. To examine the effects of thyroid function on BIA parameters we analyzed also 96 outpatients, affected by thyroid diseases in different functional conditions. We demonstrated that COVID-19 patients with low FT3 serum values exhibited increased values of the Total Body Water/Free Fat Mass (TBW/FFM) ratio. Patients with the lowest FT3 serum values had also the highest level of TBW/FFM ratio. This ratio is an indicator of the fraction of FFM as water and represents one of the best-known body-composition constants in mammals. We found an inverse correlation between FT3 serum values and this constant. Reduced FT3 serum values in COVID-19 patients were correlated with the increase in the total body water (TBW), the extracellular water (ECW) and the sodium/potassium exchangeable ratio (Na_e:K_e), and with the reduction of the intracellular water (ICW). No specific correlation was observed in thyroid patients at different functional conditions between any BIA parameters and FT3 serum values, except for the patient with myxedema, that showed a picture similar to that seen in COVID-19 patients with NTIS. Since the Na⁺/K⁺ pump is a well-known T3 target, we measured the mRNA expression levels of the two genes coding for the two major isoforms of this pump. We demonstrated that COVID-19 patients with NTIS had lower levels of mRNA of both genes in the peripheral blood mononuclear cells (PBMC)s obtained from our patients during the acute phase of the disease. In addition, we retrieved data from transcriptome analysis, performed on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM)s treated with T3 and we demonstrated that in these cells T3 is able to stimulate the expression of these two genes in a dose-dependent manner.

Conclusions

In conclusion, we demonstrated that measurement of BIA parameters is a useful method to analyze water and salt retention in COVID-19 patients hospitalized in ICU and, in particular, in those that develop NTIS. Our results indicate that NTIS has peculiar similarities with myxedema seen in severe hypothyroid patients, albeit it occurs more rapidly. The Na⁺/K⁺ pump is a possible target of T3 action, involved in the pathogenesis of the anasarcatic condition observed in our COVID-19 patients with NTIS. Finally, measurement of BIA parameters may represent good endpoints to evaluate the benefit of future clinical interventional trials, based on the administration of T3 in patients with NTIS.

Effects of Anorexia Nervosa on Bone Metabolism

Anorexia nervosa is a psychiatric disease characterized by a low-weight state due to self-induced starvation. This disorder, which predominantly affects women, is associated with hormonal adaptations that minimize energy expenditure in the setting of low nutrient intake. These adaptations include GH resistance, functional hypothalamic amenorrhea, and nonthyroidal illness syndrome. Although these adaptations may be beneficial to short-term survival, they contribute to the significant and often persistent morbidity associated with this disorder, including bone loss, which affects >85% of women. We review the hormonal adaptions to undernutrition, review hormonal treatments that have been studied for both the underlying disorder as well as for the associated decreased bone mass, and discuss the important challenges that remain, including the lack of long-term treatments for bone loss in this chronic disorder and the fact that despite recovery, many individuals who experience bone loss as adolescents have chronic deficits and an increased risk of fracture in adulthood.

The physiology of functional hypothalamic amenorrhea associated with energy deficiency in exercising women and in women with anorexia nervosa

An energy deficiency is the result of inadequate energy intake relative to high energy expenditure. Often observed with the development of an energy deficiency is a high drive for thinness, dietary restraint, and weight and shape concerns in association with eating behaviors. At a basic physiologic level, a chronic energy deficiency promotes compensatory mechanisms to conserve fuel for vital physiologic function. Alterations have been documented in resting energy expenditure (REE) and metabolic hormones. Observed metabolic alterations include nutritionally acquired growth hormone resistance and reduced insulin-like growth factor-1 (IGF-1) concentrations; hypercortisolemia; increased ghrelin, peptide YY, and adiponectin; and decreased leptin, triiodothyronine, and kisspeptin. The cumulative effect of the energetic and metabolic alterations is a suppression of the hypothalamic-pituitary-ovarian axis. Gonadotropin releasing hormone secretion is decreased with consequent suppression of luteinizing hormone and follicle stimulating hormone release. Alterations in hypothalamic-pituitary secretion alters the production of estrogen and progesterone resulting in subclinical or clinical menstrual dysfunction.

Non-thyroidal illness in the ICU: a syndrome with different faces

BACKGROUND

Critically ill patients typically present with low or low-normal plasma thyroxine, low plasma triiodothyronine (T3), increased plasma reverse T3 (rT3) concentrations, in the absence of a rise in thyrotropin (TSH). This constellation is referred to as nonthyroidal illness syndrome (NTI). Although it is long known that the severity of NTI is associated with risk of poor outcomes of critical illness, the causality in this association has not been well investigated.

SUMMARY

In this narrative review, the different faces of NTI during critical illness are highlighted. Acute alterations are dominated by changes in thyroid hormone binding, peripheral thyroid hormone uptake, and alterations in the expression and activity of the type-1 and type-3 deiodinases. It was recently shown that at least part of these acute changes are brought about by concomitant macronutrient restriction, and this part appears adaptive and beneficial. However, the face of the NTI in the prolonged phase of critical illness is different, when patients are fully fed but continue to depend on intensive medical care. In that prolonged phase of illness, hypothalamic thyrotropin releasing hormone (TRH) expression is suppressed and explains reduced TSH secretion and whereby reduced thyroidal hormone release. During prolonged critical illness, and in the presence of adequate nutrition, several tissue responses could be interpreted as compensatory to low thyroid hormone availability, such as increased expression of monocarboxylate transporters, upregulation of type-2 deiodinase activity, and increased sensitivity at the receptor level. Infusing hypothalamic releasing factors in these prolonged critically ill patients can reactivate the thyroid axis and induce an anabolic response.

CONCLUSIONS

It is clear that the name "NTI" during critical illness refers to a syndrome with different faces. Tolerating the early "fasting response" to critical illness and its concomitant changes in thyroid hormone parameters appears to be wise and beneficial. This thus applies to the NTI present in the majority of the patients treated in intensive care units. However, the NTI that occurs in prolonged critically ill patients appears different with regard to both its causes and consequences. Future studies should specifically target this selected population of prolonged critically ill patients, and, after excluding iatrogic drug interferences, investigate the effect on outcome of treatment with hypothalamic releasing factors in adequately powered randomized controlled trials.

Anorexia nervosa and bone metabolism

Anorexia nervosa (AN) is a psychiatric disorder characterized by self-induced starvation with a lifetime prevalence of 2.2% in women. The most common medical co-morbidity in women with AN is bone loss, with over 85% of women having bone mineral density values more than one standard deviation below an age comparable mean. The low bone mass in AN is due to multiple hormonal adaptations to under nutrition, including hypothalamic amenorrhea and growth hormone resistance. Importantly, this low bone mass is also associated with a seven-fold increased risk of fracture. Therefore, strategies to effectively prevent bone loss and increase bone mass are critical. We will review hormonal adaptations that contribute to bone loss in this population as well as promising new therapies that may increase bone mass and reduce fracture risk in AN.

Endocrine responses to critical illness: novel insights and therapeutic implications

CONTEXT

Critical illness, an extreme form of severe physical stress, is characterized by important endocrine and metabolic changes. Due to critical care medicine, survival from previously lethal conditions has become possible, but many patients now enter a chronic phase of critical illness. The role of the endocrine and metabolic responses to acute and prolonged critical illness in mediating or hampering recovery remains highly debated.

EVIDENCE ACQUISITION

The recent literature on changes within the hypothalamic-pituitary-thyroid axis and the hypothalamic-pituitary-adrenal axis and on hyperglycemia in relation to recovery from critical illness was critically appraised and interpreted against previous insights. Possible therapeutic implications of the novel insights were analyzed. Specific remaining questions were formulated.

EVIDENCE SYNTHESIS

In recent years, important novel insights in the pathophysiology and the consequences of some of these endocrine responses to acute and chronic critical illness were generated. Acute endocrine adaptations are directed toward providing energy and substrates for the vital fight-or-flight response in a context of exogenous substrate deprivation. Distinct endocrine and metabolic alterations characterize the chronic phase of critical illness, which seems to be no longer solely beneficial and could hamper recovery and rehabilitation.

CONCLUSIONS

Important novel insights reshape the current view on endocrine and metabolic responses to critical illness and further clarify underlying pathways. Although many issues remain unresolved, some therapeutic implications were already identified. More work is required to find better treatments, and the optimal timing for such treatments, to further prevent protracted critical illness, to enhance recovery thereof, and to optimize rehabilitation.

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.

Bone metabolism in anorexia nervosa

Anorexia nervosa (AN), a psychiatric disorder predominantly affecting young women, is characterized by self-imposed, chronic nutritional deprivation and distorted body image. AN is associated with a number of medical comorbidities including low bone mass. The low bone mass in AN is due to an uncoupling of bone formation and bone resorption, which is the result of hormonal adaptations aimed at decreasing energy expenditure during periods of low energy intake. Importantly, the low bone mass in AN is associated with a significant risk of fractures and therefore treatments to prevent bone loss are critical. In this review, we discuss the hormonal determinants of low bone mass in AN and treatments that have been investigated in this population.

Using body mass index to predict optimal thyroid dosing after thyroidectomy

BACKGROUND

Current postoperative thyroid replacement dosing is weight based, with adjustments made after thyroid-stimulating hormone values. This method can lead to considerable delays in achieving euthyroidism and often fails to accurately dose over- and underweight patients. Our aim was to develop an accurate dosing method that uses patient body mass index (BMI) data.

STUDY DESIGN

A retrospective review of a prospectively collected thyroid database was performed. We selected adult patients undergoing thyroidectomy, with benign pathology, who achieved euthyroidism on thyroid hormone supplementation. Body mass index and euthyroid dose were plotted and regression was used to fit curves to the data. Statistical analysis was performed using STATA 10.1 software (Stata Corp).

RESULTS

One hundred twenty-two patients met inclusion criteria. At initial follow-up, only 39 patients were euthyroid (32%). Fifty-three percent of patients with BMI >30 kg/m(2) were overdosed, and 46% of patients with BMI <25 kg/m(2) were underdosed. The line of best fit demonstrated an overall quadratic relationship between BMI and euthyroid dose. A linear relationship best described the data up to a BMI of 50. Beyond that, the line approached 1.1 μg/kg. A regression equation was derived for calculating initial levothyroxine dose (μg/kg/d = -0.018 × BMI + 2.13 [F statistic = 52.7, root mean square error of 0.24]).

CONCLUSIONS

The current standard of weight-based thyroid replacement fails to appropriately dose underweight and overweight patients. Body mass index can be used to more accurately dose thyroid hormone using a simple formula.

Neuroendocrine dysregulation and the growth hormone-IGF-1 axis in anorexia nervosa

Anorexia nervosa is a common psychiatric disorder characterized by extreme, self-induced starvation and is associated with a number of medical complications, including significant loss of bone mass. Disruption of the hypothalamic-pituitary axis has been demonstrated in anorexia nervosa and contributes to both loss of established bone mass in adults and failure to accrue normal bone mass in adolescents. Anorexia nervosa is associated with the development of a state of acquired growth hormone (GH) resistance, characterized by low IGF-1 and elevated GH levels, which may be mediated in part by FGF-21. Administration of supraphysiologic recombinant human GH does not result in an increase in markers of bone formation. However, treatment with recombinant human IGF-1, in combination with an oral contraceptive, increases markers of bone formation as well as bone mineral density, and may be a novel way to treat the bone loss associated with anorexia nervosa.

Eating disorders: progress and challenges

BACKGROUND

Eating disorders are common health problems afflicting mainly female adolescents and young women. They are associated with important physical health and psychosocial morbidity, and carry increased risk of death. Their cause is not yet completely understood and their management is complex, with some patients resisting all available treatments. AIMS OF THIS REVIEW: To provide the readers with an update regarding our knowledge and understanding of eating disorders.

METHODS

Medline database has been used for searching articles on eating disorders published since 1980. The key words used were eating disorders, anorexia nervosa, bulimia nervosa, bulimia, and binge eating. Professional books published during this period has been also reviewed.

CONCLUSIONS

In the last 30 years a substantial improvement has been achieved both in the understanding and management of eating disorders, but many problems still need to be resolved. Three principal priorities should be addressed. First, the actual classification of eating disorders should be revised, since about half the cases seen in clinical practice receive a diagnosis of eating disorder not otherwise specified, and it is common to observe a migration between eating disorder diagnoses. Second, the research on pathogenesis should better clarify the exact role of genetic and environmental risk factors, and how they interact and vary across the development and maintenance of eating disorders. Third, there is an urgent need both to disseminate the few evidence-based treatments available, and to develop more potent treatments for all the eating disorder diagnostic categories.

Do thyroid hormones mediate the effects of starvation on mood in adolescent girls with eating disorders?

In the eating disorders (ED) comorbid depression is common and clinical experience suggests that it is partly related to starvation. Starvation affects thyroid hormone status and thyroid hypofunction is in turn associated with depressed mood. We have therefore investigated the possibility that thyroid hormones and starvation are associated with mood in ED. Two-hundred and thirty-nine adolescent girls were examined at presentation of an ED. Analyses of thyroid hormones, documentation of weight and weight changes, self-reports of depressive symptomatology and clinical diagnoses of ED and depression were used in the analyses. Of the 239 girls 100 were diagnosed with depression. The girls with and without depression did not differ in age, weight, height, body mass index (BMI), weight loss or duration of disease. Plasma free thyroxine concentrations were lower in depressed girls (11.9±1.7 versus 12.8±1.9 pmol/L; p<0.01). Plasma triodothyronine and thyroid-stimulating hormone concentrations did not differ between groups. In a logistic regression analysis the odds ratio for depression was 41.1 (95% confidence interval 4.18-405; p=0.001) for a 10 pmol/L change of plasma free thyroxine after correction for BMI, weight loss, duration of disease, rate of weight loss, plasma triodothyronine and an interaction between BMI and plasma free thyroxine. BMI did not predict depression. Low circulating thyroxine concentrations may provide a link between starvation and depression in adolescent girls with ED.

BMI, body composition, and the energy requirement for body weight gain in patients with anorexia nervosa

OBJECTIVE

Theories abound about the energy requirements for body weight gain in anorexia nervosa (AN). We hypothesized that malnutrition status affects the energy requirements.

METHOD

On admission, 97 AN patients were measured for body composition by dual-energy X-ray absorptiometry. The relationship between body mass index (BMI) and body composition was investigated. In addition, 21 patients who completed our treatment program were tested for energy intake and body weight.

RESULTS

The relationship between BMI and both fat-free mass and fat mass (FM) on admission was curvilinear. The weight gain per excess energy was greater in the group of patients with FM < 4 kg or BMI < 14 kg/m(2) than in the group with FM > or = 4 kg or BMI > or = 14 kg/m(2) (p = .037, p = .055, respectively).

DISCUSSION

The energy requirements for weight gain in AN patients are related to the initial FM and BMI.

The endocrinopathies of anorexia nervosa

OBJECTIVE

To describe the hormonal adaptations and alterations in anorexia nervosa.

METHODS

We performed a PubMed search of the English-language literature related to the pathophysiology of the endocrine disorders observed in anorexia nervosa, and we describe a case to illustrate these findings.

RESULTS

Anorexia nervosa is a devastating disease with a variety of endocrine manifestations. The effects of starvation are extensive and negatively affect the pituitary gland, thyroid gland, adrenal glands, gonads, and bones. Appetite is modulated by the neuroendocrine system, and characteristic patterns of leptin and ghrelin concentrations have been observed in anorexia nervosa. A thorough understanding of refeeding syndrome is imperative to nutrition rehabilitation in these patients to avoid devastating consequences. Although most endocrinopathies associated with anorexia nervosa reverse with recovery, short stature, osteoporosis, and infertility may be long-lasting complications. We describe a 20-year-old woman who presented with end-stage anorexia nervosa whose clinical course reflects the numerous complications caused by this disease.

CONCLUSIONS

The effects of severe malnutrition and subsequent refeeding are extensive in anorexia nervosa. Nutrition rehabilitation is the most appropriate treatment for these patients; however, it must be done cautiously.

Criminally prosecuted cases of child starvation

OBJECTIVE

Here we describe the clinical findings and legal outcomes in 12 prosecuted cases of infant and child starvation.

METHODS

Medical records, investigation records, and transcripts of court testimony were reviewed in the cases of 12 infants and children from locations throughout Texas who had been starved deliberately. The children's ages ranged from 2 months to 13 years. The caretakers of all children received both civil and criminal charges; cases were tried over an 11-year time span. Clinical presentations, examination findings, laboratory findings, symptoms of refeeding syndrome, and legal outcomes were examined. Two illustrative cases are presented in detail here.

RESULTS

Of the 12 cases reviewed, the median age was 2.7 years, with a range of 2.25 months to 13 years 7 months. Half of the children died shortly before or soon after presentation for medical care or to law enforcement. Survival was more common in older children than in infants. Most of the children were secluded from others, and all had access to food denied or severely restricted. Caretakers claimed few, benign, or no past medical illnesses in the children. Based on weight and height measurements, 10 of the children had severe wasting and stunting, and 2 had mild or moderate wasting. There was a tendency toward more severe wasting in the fatal cases. All children manifested multiorgan effects of starvation. All survivors manifested complications with refeeding. Approximately half of the children had past or present injuries or history suggestive of physical or sexual abuse. Parental rights were terminated in all cases. A total of 25 individuals were charged criminally; 23 were found guilty or pled guilty, and trials for 2 individuals were pending at the time of this writing. The types of criminal charges and punishment varied from deferred adjudication to a life sentence.

CONCLUSIONS

Life-threatening criminal starvation of infants and children is a rare and severe form of child maltreatment. In our series, infants were more wasted at the time of presentation and less likely to survive prolonged starvation than were older children. As with other forms of child abuse, caretakers' histories regarding the children's illnesses were inconsistent with the severity and chronicity of the children's degree of wasting. All victims in our series showed multiorgan effects of chronic malnutrition and deprivation, and all survivors developed refeeding complications and required prolonged periods of recovery.

Complicações clínicas da anorexia nervosa e bulimia nervosa

Os transtornos alimentares estão associados a diversas complicações clínicas graves. Distúrbios hidroeletrolíticos e metabólicos assim como várias alterações endócrinas podem estar presentes, muitas dessas decorrentes da perda de peso e dos métodos compensatórios utilizados pelos pacientes. São importantes a identificação precoce e o manuseio adequado dessas complicações para a redução dos riscos relacionados. O objetivo desse artigo é discutir as complicações clínicas associadas com a anorexia nervosa e a bulimia nervosa.

Hypothalamic amenorrhea. The effects of environmental stresses on the reproductive system: a central effect of the central nervous system

Although the treatment of anovulation has become significantly more specialized and complex in the centuries since Hippocrates, a complete understanding of the causes and mechanisms of hypothalamic amenorrhea has not been achieved. Even the best research on hypothalamic amenorrhea is plagued by the lack of longitudinal studies, the use of different exercise models, the difficulty of controlling for caloric intake, and the fact that genetics may have a role in the disorder. Continuing research on metabolic rate, leptin, and other factors will ultimately answer many of the outstanding questions and will help to create better tools for treating this disorder.

Eating disorders

Eating disorders are common among adolescent girls and young women and are associated with potentially serious medical complications, yet they often go undetected and untreated. All patients with eating disorders should be evaluated and treated for medical complications of the disease at the same time that psychotherapy and nutritional counseling are undertaken. Pharmacologic agents are often useful as adjuncts to psychotherapy for bulimia nervosa or binge-eating disorder; in the case of anorexia nervosa, psychotropic medication is generally reserved for patients with a concurrent psychiatric illness or those who have recovered some weight.

Brain hypometabolism of glucose in anorexia nervosa: a PET scan study

Cerebral glucose metabolism was studied in 20 underweight anorectic girls and in 10 age- and sex-matched healthy volunteers using positron emission tomography with (18-F)-fluorodeoxy-glucose. Both groups were scanned during rest, with eye closed and with low ambient noise. Compared to controls, the underweight anorectic group showed a global hypometabolism (p = .002) and an absolute (p < .001) as well as relative (p < .01) hypometabolism of glucose in cortical regions, with the most significant differences found in the frontal and the parietal cortices. Within the underweight anorectic and the control groups, no correlations were found between absolute or relative rCMRGlu and BMI, anxiety scores, or Hamilton scores of depression. Different factors might explain this reduction of glucose metabolism in anorexia nervosa. It might be the consequence of neurophysiological or morphological aspects of anorexia nervosa and/or the result of some associated symptoms such as anxiety or depressed feelings. Supported by cognitive studies, we can also hypothesize a primary corticocerebral dysfunctioning in anorexia nervosa.

The medical complications of anorexia nervosa

The physical complications of anorexia nervosa are common and can be life threatening, but psychiatrists and the increasing number of non-medical therapists involved in treatment programmes often overlook these complications. Cardiovascular complications are the most common, and the most likely to result in fatalities, particularly in those patients who vomit, purge or abuse diuretics, because of the electrolyte abnormalities induced. Osteoporosis is an early and perhaps irreversible consequence of severe weight loss. Further, there are dangers in rapid intravenous hyperalimentation.

Rapid escape of cortisol from suppression in response to i.v. dexamethasone in anorexia nervosa

The suppressive effect of dexamethasone (Dex) on plasma cortisol and beta-lipotrophin (beta LPH) was investigated in patients with anorexia nervosa. Dex was given either orally, 1 mg at 2400 h, with blood sampling at 0800 h on the days before and after Dex, or by i.v. infusion starting at 1100 h (1 mg/h) for 4 h with sampling at 0800, 1100, 1500, 2000 and 2400 h and at 0800 h the following day. The plasma cortisol and beta LPH levels during oral or i.v. Dex administration were compared between patients and normally menstruating women of normal weight. The results showed that Dex administration depressed cortisol significantly (P less than 0.0001) during oral or i.v. infusion in most patients, without, however, suppressing it entirely as is the case in normal women. Moreover, during i.v. Dex infusion, the concentrations of cortisol escaped suppression and were higher than in normal women (less than 50 nmol/l) by 0800 h on the day following infusion. In the patients who were reinvestigated after re-feeding and weight gain (n = 9), a normal suppression of cortisol in response to i.v. Dex infusion was observed in only five cases and a slight failure to suppress, although concentrations were lower than before refeeding, was still evident in four. We concluded that, in anorexia nervosa, cortisol concentration rapidly escapes suppression by Dex administration, and that this escape is not related to the degree of starvation.

How do eating disorders affect thyroid function?

Abnormal thyroid function in patients with eating disorders can result from malnutrition. A low serum triiodothyronine (T3) level is commonly noted in starvation states and is caused by reduced peripheral conversion of thyroxine (T4) to T3. Diminished T4 concentrations are also observed. Adequate nutrition normalizes this type of aberrant laboratory profile. Thyroid function tests that give results below the normal range are best repeated initially for verification of results and again after adequate nutrition is reestablished. If no primary endocrinopathy is present, spontaneous correction of these laboratory values can be expected with conventional dietary habits.

Sex hormone binding globulin in women with anorexia nervosa

In 29 women with anorexia nervosa, on a blood sample withdrawn at 0900 h before and during weight gain, the binding parameters of serum sex hormone binding globulin (SHBG) were measured by a solid phase method and the levels of testosterone, oestradiol and thyroid hormones were measured by radioimmunoassay. The binding capacity of SHBG was higher than the upper limit for normally menstruating women in 23 patients whilst its affinity for binding testosterone at 37 degrees C was normal (0.32-0.53 X 10(-9) mol/l). The mean levels of testosterone, oestradiol and free thyroxine were normal and the mean level of triiodothyronine was significantly (P less than 0.005) decreased. The binding capacity of SHBG did not correlate significantly with body mass index, percent weight lost, thyroid hormone or sex hormone levels. In 9 patients, an i.v. infusion providing 1200-1400 calories daily was given for 1 week. In these patients a significant decrease (P less than 0.005) in the binding capacity of SHBG (from 74.7 +/- 26.7 to 52.9 +/- 21.8 nmol/l) and a significant increase (P less than 0.001) in T3 levels (from 0.69 +/- 0.21 to 0.95 +/- 0.13 nmol/l) was observed. In 14 patients, when a weight gain of at least 5% was obtained, the binding capacity of SHBG fell into the normal range (25.6-62.9 nmol/l) while T3 levels rose to normal (0.85-2.30 nmol/l). These findings suggested that variations of calorie intake and/or body weight may influence the binding capacity of SHBG in the human.

Altered erythrocyte Na-K pump in anorectic patients

The status of the erythrocyte sodium pump was evaluated in a group of patients suffering from anorexia nervosa and a group of healthy female control subjects. Anorectic patients showed significantly higher mean values of digoxin-binding sites/cell (ie, the number of Na-K-ATPase units) with respect to control subjects while no differences were found in the specific 86Rb uptake (which reflects the Na-K-ATPase activity) between the two groups. A significant correlation was found between relative weight and the number of Na-K-ATPase pump units (r = -0.66; P less than 0.0001). Anorectic patients showed lower serum T3 concentrations (71.3 +/- 53 ng/dL) with respect to control subjects (100.8 +/- 4.7 ng/dL; P less than 0.0005) and a significant negative correlation between T3 levels and the number of pump units (r = -0.52; P less than 0.003) was found. Our study therefore shows that the erythrocyte Na-K pump may be altered in several anorectic patients. We suggest that this feature could be interrelated with the degree of underweight and/or malnutrition.

The thyroid function in young men during prolonged exercise and the effect of energy and sleep deprivation

Thyroid function has been investigated in 24 young military cadets participating in a 5 d ranger training course with heavy physical exercise, calorie deficiency and deprivation of sleep. The cadets were divided into three groups, each differing in the amount of sleep and food consumption. The serum levels of thyroid hormones (T4, FT4, T3, rT3) and TBG showed a biphasic pattern during the course. Initially there was an increased secretion concomitant with an increased deiodination of T4 to T3 and rT3 mainly due to physical exercise. When the activities lasted for several days without sufficient food supply the thyroid secretion decreased simultaneously with an alteration of the peripheral conversion of T4 to rT3 instead of T3. A significant correlation was found between the changes in total and free thyroxine (r = 0.9) and between the increase in rT3 and decrease in T3 (r = 0.6). TSH decreased during the first day of activities and remained low throughout the course. The TSH response to TRH stimulation was greatly reduced during the course due to physical exercise and calorie deficiency. The present investigation demonstrates that the thyroid function is strongly affected by prolonged physical exercise and a negative energy balance, whereas sleep deprivation does not have any significant influence. The results indicate that the alteration observed is not regulated just by the hypothalamo-pituitary-thyroid-axis alone.

Variations of thyroid hormones during total fasting in obese and in obese diabetic subjects

Fasting and hypocaloric diets are known to induce a reduction of triiodothyronine (T3) and to increase reverse triiodothyronine (rT3) in normal and obese subjects. The effect of 8-day fasting was evaluated on T3, thyroxine (T4), free T4, rT3, TSH, immunoreactive insulin (IRI), thyroxine binding globulin (TBG) and glycemia in 21 obese subjects (5 males, 16 females) grouped according to the average starting blood glucose concentration in: group I, diabetic obese subjects (9 patients); group II, non diabetic obese subjects (12 patients). All patients had no history of recent weight loss due to dietetic therapy or drugs. Blood samples were drawn in the morning at 0, 2, 4, 6, 8 days after total caloric deprivation and 2 days after refeeding. A superimposable variation of weight and glucose concentration were seen in both groups. In addition, no difference was observed in ketone body excretion, SH, TBG, T4, free T4. In group II a significant decrease of IRI was observed during diet (p less than 0.05); T3 decreased (p less than 0.01) and rT3 increased (p less than 0.01) significantly. No variations in T3 and rT3 values were observed in group I. These results are consistent with a possible role of glucose metabolism in the genesis of the low T3 syndrome.

Neuroendocrine alterations in systemic disease

Systemic disorders clearly may exert a significant influence on neuroendocrine function. Disorders that cause significant stress to the body, either physical or psychological, may cause a resetting upward of the HPA axis to provide sufficient cortisol to counteract the stress and to help sustain energy substrate levels. GH levels also increase in many of these situations, again promoting sufficient energy substrate levels. In some circumstances the concomitantly low somatomedin activity may be speculated to be adaptative to prevent the insulin-like agonist activity of these substances as well as to prevent energy expenditure in body growth. However, in other situations such as chronic renal failure and cirrhosis, the decreased somatomedin activity may be primary, causing decreased feedback at the hypothalamic-pituitary level and increased GH levels. The stress-induced rise in PRL may also play a minor role in preserving energy substrate since high levels may promote insulin resistance. In most illnesses the 'euthyroid sick syndrome' develops. Whether such patients are 'euthyroid' or mildly hypothyroid is a matter of controversy. The fact that protein losses are increased during fasting when the lowered T3 levels are returned to normal with exogenous T3 supplementation suggests that these patients are indeed hypothyroid and this hypothyroidism serves to conserve energy substrate by decreasing the metabolic rate. The reproductive axis is often impaired with systemic illness. Again, teleologically this may be viewed as an inactivation of non-essential functions in times of stress. It would appear that the changes that occur with systemic illness, in general, are favourable to the organism in that they promote survival. The detailed neurotransmitter and hypophyseotrophic hormone changes resulting in the alteration in pituitary function remain to be elucidated for the most part.

Delayed TSH release in anorexia nervosa following injection of thyrotropin-releasing hormone (TRH)

We studied plasma concentrations of thyrotropin (TSH), prolactin and growth hormone (GH) after injection of 500 microgram of thyrotropin-releasing hormone (TRH) in 10 patients with acute anorexia nervosa, subsequent to initial nutritional stabilization and again after weight recovery. Plasma thyroxine levels were normal throughout, whereas plasma triiodothyronine levels were low initially but rose with weight gain. The TSH secretory response to TRH was delayed and prolonged during the initial study but showed a normal overall quantitative response, except for two patients who showed no TSH rise. Following weight gain the TSH response was more rapid, and positive correlations were found between body weight and peak TSH levels and rapidity of TSH response. Six of 10 patients, however, continued to exhibit a delayed TSH peak response, the average response was markedly increased in comparison with that in normal females. The prolactin response curves were normal at both times. Rises in GH following TRH were observed in two patients prior to and in one patient after weight gain. We conclude that acute anorexia nervosa, with its concomitant profound weight loss, is accompanied by abnormalities in the hypothalamo-pituitary-thyroid axis, which are reversed only in part with improvement in the illness and weight gain, suggesting the persistence of disordered neuroendocrine function in this illness.

The effect of a high calory diet on hormonal changes in young men during prolonged physical strain and sleep deprivation

Major changes occur in the serum level of several hormones during 5 days of heavy and continuous physical activities, with less than a total of 2 h of sleep. The present investigation was designed to evaluate the importance of caloric deficiency, energy requirement being about 8,000-10,000 kcal/24 h. A comparison between well fed subjects and those with food deprivation revealed significantly higher levels of (T3) triiodothyronin, insulin and thyroid stimulating hormone (TSH) in the well-fed subjects, who also had lower levels of growth hormone (hGH) and cortisol, whereas no difference was found between the two groups for thyroxin (T4). Increased levels were found for T3 and T4 in both groups during the first day of activity, with a concomitant decrease in TSH and a subsequent decrease of T4 during the next 2 days. T3 decreased only in the low-calory group whereas increased levels were found in the iso-calory group throughout the course. The resting levels of insulin decreased during the course in the low-calory group whereas it increased in the iso-calory group. High levels were maintained throughout the course for hGH. Cortisol showed high levels just before the start of the course and then decreased from day 2 to day 4. No difference was found between the morning and evening levels for cortisol, indicating disappearance of the circadian rhythm. The present investigation has shown that energy deficiency during prolonged physical strain is responsible for the decreased serum levels of T3 and insulin and may contribute to the decrease in TSH and the increase in hGH and cortisol.