Catecholamine metabolism in primary anorexia nervosa

Abnormalities in neuroendocrine function and sympathetic nervous system activity appear to be present in primary anorexia nervosa. Hypothalamic catecholamines are involved in control of endocrine function and norepinephrine is released from sympathetic nerve endings. Because of possible abnormalities in catecholamine metabolism, plasma levels of norepinephrine and urinary excretion of homovanillic acid and 3-methoxy-4-hydroxyphenyl glycol were studied in female patients with primary anorexia nervosa before and after significant clinical improvement and compared with normal female volunteers. During the phase of the disease in which body weights were more than 20--25% below ideal, patients' blood pressures and pulse rates, plasma levels of norepinephrine, and 24-h urinary excretion of 3-methoxy-4-hydroxyphenol glycol and homovanillic acid were lower than those of a group of normal volunteers. After weight gain, these parameters increased to near-normal levels. At no time was plasma dopamine-beta-hydroxylase activity abnormal. The results suggest that abnormalities in catecholamine metabolism in primary anorexia nervosa are caused by starvation, and that neuronal functions dependent on aminergic neurotransmission may be altered as a result.     

Bone metabolism in adolescents with anorexia nervosa

Adolescents with anorexia nervosa (AN) are at risk for low bone mass at multiple sites, associated with decreased bone turnover. Bone microarchitecture is also affected, with a decrease in bone trabecular volume and trabecular thickness, and an increase in trabecular separation. The adolescent years are typically the time when marked increases occur in bone mass accrual towards the attainment of peak bone mass, an important determinant of bone health and fracture risk in later life. AN often begins in the adolescent years, and decreased rates of bone mass accrual at this critical time are therefore also concerning for deficits in peak bone mass. Factors contributing to low bone density and decreased rates of bone accrual include alterations in body composition such as low body mass index and lean body mass, and hormonal alterations such as hypogonadism, a nutritionally acquired resistance to GH and low levels of IGF-I, relative hypercortisolemia, low levels of leptin, and increased adiponectin (for fat mass) and peptide YY. Therapeutic strategies include optimizing weight and menstrual recovery, and adequate calcium and vitamin D replacement. Oral estrogen-progesterone combination pills are not effective in increasing bone density in adolescents with AN. Recombinant human IGF-I increases levels of bone formation markers in the short term, while long-term effects remain to be determined. Bisphosphonates act by decreasing bone resorption, and are not optimal for use in adolescents with AN, in whom the primary defect is low bone formation.     

Bone metabolism in anorexia nervosa and hypothalamic amenorrhea

Anorexia nervosa (AN) and hypothalamic amenorrhea (HA) are states of chronic energy deprivation associated with severely compromised bone health. Poor bone accrual during adolescence followed by increased bone loss results in lifelong low bone density, degraded bone architecture, and higher risk of fractures, despite recovery from AN/HA. Amenorrhea is only one of several compensatory responses to the negative energy balance. Other hypothalamic-pituitary hormones are affected and contribute to bone deficits, including activation of hypothalamic-pituitary-adrenal axis and growth hormone resistance. Adipokines, particularly leptin, provide information on fat/energy stores, and gut hormones play a role in the regulation of appetite and food intake. Alterations in all these hormones influence bone metabolism. Restricted in scope, current pharmacologic approaches to improve bone health have had overall limited success.     

Bone metabolism in adolescent boys with anorexia nervosa

BACKGROUND: Anorexia nervosa (AN) is a condition of severe undernutrition associated with low bone mineral density (BMD) in adolescent females with this disorder. Although primarily a disease in females, AN is increasingly being recognized in males. However, there are few or no data regarding BMD, bone turnover markers or their predictors in adolescent AN boys. HYPOTHESES: We hypothesized that BMD would be low in adolescent boys with AN compared with controls associated with a decrease in bone turnover markers, and that the gonadal steroids, testosterone and estradiol, and levels of IGF-I and the appetite regulatory hormones leptin, ghrelin, and peptide YY would predict BMD and bone turnover markers. METHODS: We assessed BMD using dual-energy x-ray absorptiometry and measured fasting testosterone, estradiol, IGF-I, leptin, ghrelin, and peptide YY and a bone formation (aminoterminal propeptide of type 1 procollagen) and bone resorption (N-telopeptide of type 1 collagen) marker in 17 AN boys and 17 controls 12-19 yr old. RESULTS: Boys with AN had lower BMD and corresponding Z-scores at the spine, hip, femoral neck, trochanter, intertrochanteric region, and whole body, compared with controls. Height-adjusted measures (lumbar bone mineral apparent density and whole body bone mineral content/height) were also lower. Bone formation and resorption markers were reduced in AN, indicating decreased bone turnover. Testosterone and lean mass predicted BMD. IGF-I was an important predictor of bone turnover markers. CONCLUSION: AN boys have low BMD at multiple sites associated with decreased bone turnover markers at a time when bone mass accrual is critical for attainment of peak bone mass.     

Fuel metabolism in anorexia nervosa and simple obesity

To examine insulin sensitivity and the relative contribution of different fuels to energy metabolism in anorexia nervosa and obesity, we measured oxidation (indirect calorimetry) of glucose, lipids, and proteins in the basal state and during an insulin clamp (+45 mU/m2.min) in 11 women with anorexia nervosa (age, 25 +/- 3 years; body mass index [BMI], 13.6 +/- 0.4 kg/m2; fat mass, 15.7% +/- 1.6%), eight obese women (age, 31 +/- 3; BMI 36.0 +/- 1.5; fat mass, 47.1% +/- 1.9%), and eight controls (age, 26 +/- 3; BMI, 21.8 +/- 0.9; fat mass, 25.7% +/- 3.6%). Expressed per lean body mass, (LBM), glucose disposal was equally reduced in anorectics (7.53 +/- 0.62 mg/kg LBM.min) and obese (6.80 +/- 1.07 mg/kg LBM.min) compared with controls (10.64 +/- 0.69 mg/kg LBM.min; P less than .01). The reduction in glucose disposal in anorectics was primarily due to a significant (P less than .01) reduction in glucose storage, while glucose oxidation was normal. In obese women, both storage and oxidation of glucose were reduced compared with controls (P less than .01). Basal energy expenditure was similar in anorectic, obese, and control subjects (20.6 +/- 1.00, 23.7 +/- 0.56, 23.2 +/- 1.36 cal/kg LBM.min, respectively). However, the contribution of glucose, lipids, and proteins to basal energy expenditure differed between anorectic (62%, 16%, 22%), obese (26%, 58%, 16%), and control (30%, 54%, 16%) subjects (P less than .05 v all). In conclusion, in anorexia nervosa, insulin stimulates glucose oxidation more than storage. In obesity, both components of insulin-stimulated glucose metabolism are impaired.(ABSTRACT TRUNCATED AT 250 WORDS)     

Insulin-stimulated glucose disposal is not increased in anorexia nervosa

Insulin-stimulated glucose disposal was investigated using the euglycemic hyperinsulinemic glucose clamp technique in six women with anorexia nervosa (27.3 +/- 4.9 yr old; weight, 38.8 +/- 6.6 kg) and compared to results obtained in six normal women (22.6 +/- 1.2 yr old; weight, 58 +/- 2.5 kg) and seven obese women (26.8 +/- 7.7 yr old; weight, 92.5 +/- 13.8 kg). The glucose clamp was performed for 2 h using the Biostator and a continuous insulin infusion of 100 mU kg-1 h-1. Plasma levels of insulin were determined at 30-min intervals. Plasma levels of glucagon, FFA, glycerol, 3-hydroxy-butyrate, and alanine were measured basally. Blood glucose levels were similar in normal subjects and anorectic patients; they were slightly but significantly higher in the obese patients. The indices of insulin sensitivity measured were the MCR of glucose and the ratio of glucose infused to insulin infused (G/I). They were very similar in anorectic subjects [MCR, 13.5 +/- 2.4 (+/- SEM) ml kg-1 min-1; G/I, 5.2 +/- 0.9 mg/mU) and normal subjects (MCR, 13.5 +/- 1.7 ml kg-1 min-1; G/I, 5.2 +/- 0.4 mg/mU), but were significantly reduced in obese patients (MCR, 5.1 +/- 0.8 ml kg-1 min-1; G/I, 2.6 +/- 0.3 mg/mU; P less than 0.0025). Differences in plasma insulin among the three groups were not statistically significant. Plasma alanine levels were higher in anorectic than in normal or obese subjects, suggesting defective gluconeogenesis. Thus, insulin-stimulated glucose disposal is normal in patients with anorexia nervosa, a finding that contrasts with the previously reported increase in erythrocyte insulin receptors in this disease.     

Glucose metabolism during ghrelin infusion in patients with anorexia nervosa

Anorexia nervosa (AN) is an eating disorder characterized by self-induced starvation due to fear of adiposity. Ghrelin, gastric peptide with potent orexigenic, adipogenic, GH-releasing and metabolic properties, is elevated in AN. We have previously shown that intervention with exogenous ghrelin is not effective in terms of inducing neuroendocrine and appetite responses in AN. In this arm of the same study protocol we investigated glucose metabolism responses to 5 h i.v. infusion of active ghrelin in a) 9 severely malnourished AN patients, b) 6 AN patients who partially recovered body weight (PRAN), c) 10 constitutionally thin female subjects with regular menstrual cycles. At baseline, no significant differences were observed in blood glucose, insulin, c-peptide, adiponectin, and homeostasis model assessment index values, between the studied groups. During ghrelin infusions, blood glucose levels significantly increased in all groups although significantly less in low-weight AN; insulin levels were not significantly affected, while c-peptide levels were significantly suppressed only in the constitutionally thin and PRAN subjects. In addition to our previous findings of impaired neuroendocrine and appetite responses in patients with AN, we conclude that metabolic responses to ghrelin are attenuated in these patients, which tend to recover with weight gain.     

Osteoporosis in anorexia nervosa

Anorexia nervosa (AN) has recently become one of common disorders in adolescent girls. A chronic course of AN is related to morbidity, with one of the most serious medical complications being severe osteopenia. The prevalence of osteoporosis is estimated to be 40 % in AN during the follow up. The incidence of bone fracture in AN after the recovery of body weight is reported to be two to seven higher than that in healthy age-matched controls. Because adolescence is a critical time in terms of acquisition of peak bone mass, osteopenia during this time may be permanent. Adult woman with adolescence-onset AN has lower bone mineral density than that with adult-onset AN. In addition, bone mineral density (BMD) of AN has been shown to be influenced by several factors, including reduced body weight due to malnutrition, intake of calcium and vitamin D, and duration of estrogen deficiency. Among them, body weight is known to be the most important prognostic factor, both in a short and long period of years. Thus, medical doctor should monitor BMD in patients with AN throughout their life.     

Adiponectin in anorexia nervosa and bulimia nervosa

To study the role of adiponectin, a novel adipocyte-specific secreted protein, on the pathophysiology of eating disorders, circulating levels of fasting adiponectin, leptin, insulin, and glucose were measured in 31 female patients with anorexia nervosa (AN) and in 11 with bulimia nervosa. Hormone levels were compared with 16 age-matched, normal body weight controls, six healthy constitutionally thin subjects, and nine obese subjects. Moreover, changes in levels were reevaluated after nutritional treatment and weight gain in 13 patients with AN. Serum adiponectin concentrations in AN and bulimia nervosa were significantly lower than those in normal-weight controls. These results were unexpected because the levels were high in constitutionally thin subjects and low in obese subjects, which provide a negative correlation with body mass index (BMI) and body fat mass. In contrast, serum leptin levels correlated very well with BMI and fat mass among all the patients and controls. The insulin resistance was significantly low in AN and high in obese subjects. The concentrations of adiponectin after weight recovery increased to the normal level despite a relatively small increase in BMI. These findings suggest that abnormal feeding behavior in the patients with eating disorders may reduce circulating adiponectin level, and weight recovery can restore it.     

The effects of anorexia nervosa on bone metabolism in female adolescents

Osteopenia is a frequent, often persistent, complication of anorexia nervosa (AN) in adolescent girls and occurs during a critical time in bone development. Little is known about bone metabolism in this patient population. Therefore, we measured bone density (BMD) and body composition by dual energy x-ray absorptiometry, nutritional status, bone turnover, calcium, and hormonal status in 19 adolescent girls with AN (mean +/- SEM, 16.0+/-0.4 yr) and 19 bone age-matched controls. The mean duration of AN was 19+/-5 months. Spinal (L1-L4) osteopenia was common in AN. Lumbar anterioposterior BMD was more than 1 SD below the mean in 42% of patients, and lateral spine BMD was more than 1 SD below in 63% of patients compared with controls. Lean body mass significantly predicted lumbar bone mineral content (r = 0.75; P < 0.0001) in controls only. In AN, duration of illness was the most significant predictor of spinal BMD (lumbar: r = -0.44; P = 0.06; lateral: r = -0.59; P = 0.008). AN adolescents with mature BA (15 yr and greater) were hypogonadal [estradiol, 16.2+/-1.9 vs. 23.3+/-1.6 pg/mL (P = 0.01); free testosterone, 0.70+/-0.17 vs. 1.36+/-0.14 pg/mL (P = 0.01)] although dehydroepiandrosterone sulfate and urinary free cortisol levels did not differ. Leptin levels were reduced in AN (2.9+/-2.1 vs. 16.5+/-1.8 ng/mL; P < 0.0001). Insulin-like growth factor I (IGF-I) was reduced in AN to 50% of control levels (219+/-41 vs. 511+/-35 ng/mL; P < 0.0001) and correlated with all measures of nutritional status, particularly leptin (r = 0.80; P < 0.0001). Surrogate markers of bone formation, serum osteocalcin (OC) and bone-specific alkaline phosphatase (BSAP), were significantly (P = 0.02) reduced in AN vs. controls (OC, 39.1+/-6.4 vs. 59.2+/-5.2 ng/mL; BSAP, 27.9+/-4.0 vs. 40.6+/-3.4 U/L). The majority of the variation in bone formation in AN was due to IGF-I levels (OC: r2 = 0.72; P = 0.002; BSAP: r2 = 0.53; P = 0.01) in stepwise regression analyses. Bone resorption was comparable in patients and controls. These data demonstrate that bone formation is reduced and uncoupled to bone resorption in mature adolescents with AN in association with low bone density. Lean body mass was a significant predictor of BMD in controls, but not AN patients. The major correlate of bone formation in AN was the nutritionally dependent bone trophic factor, IGF-I. Reduced IGF-I during the critical period of bone mineral accumulation may be an important factor in the development of osteopenia in adolescents with AN.     

Hyperadiponectinaemia in anorexia nervosa

OBJECTIVE: Adiponectin (ApN) is a fat-derived hormone that enhances insulin sensitivity, controls body weight, prevents atherosclerosis and negatively regulates haematopoiesis and immune functions. In contrast to many proteins secreted by adipose tissue, the circulating level of ApN falls in obesity and insulin resistance states. The influence of starvation-induced depletion of fat stores on ApN concentrations is yet unknown. We therefore investigated plasma ApN in anorexia nervosa (AN). PATIENTS AND DESIGN: We measured plasma ApN in 26 female anorectic patients and examined its relationships to several anthropometric or metabolic parameters. Twenty-four age-matched healthy female controls (C) were also studied. RESULTS: Body mass index (BMI) and fat mass were markedly decreased in AN. However, plasma ApN levels were 30% higher in anorectic than in control subjects (P < 0.01), while a reverse pattern was observed for leptin concentrations. When normalized for fatness, ApN values almost doubled in AN. ApN levels were negatively correlated with BMI and fat mass (P < 0.05 in the combined population, AN + C). Insulin sensitivity tended to be 40% higher in AN (n = 7) than in C (n = 12) subjects, and plasma ApN levels were positively correlated with insulin sensitivity (P < 0.05 in AN + C subgroups). Total and low density lipoprotein (LDL)-cholesterol were higher, or tended to be higher, in AN, but there were no correlations between plasma ApN and plasma lipids. By contrast, ApN was related to the lipid profile, in a manner consistent with its antiatherogenic role, in healthy controls [i.e. negatively correlated with triglycerides, total and LDL-cholesterol and total/high density lipoprotein (HDL) cholesterol; P < 0.05 or less for each parameter]. In a multiple regression analysis, BMI and insulin sensitivity in AN were independent determinants for ApN levels, explaining up to approximately 80% of the variance in this measure. CONCLUSIONS: Plasma adiponectin levels are increased in anorexia nervosa. This may, at least in part, be due to the lack of negative feedback exerted by fat mass on adiponectin production and/or to enhanced insulin sensitivity. We speculate that hyperadiponectinaemia could, in turn, contribute to maintain a state of enhanced insulin sensitivity and possibly exacerbate haematological and infectious complications of anorexia nervosa.     

Endocrine abnormalities in anorexia nervosa

Anorexia nervosa (AN) is a psychiatric disease associated with notable medical complications and increased mortality. Endocrine abnormalities, including hypogonadotropic hypogonadism, hypercortisolemia, growth hormone resistance and sick euthyroid syndrome, mediate the clinical manifestations of this disease. Alterations in anorexigenic and orexigenic appetite-regulating pathways have also been described. Decreases in fat mass result in adipokine abnormalities. Although most of the endocrine changes that occur in AN represent physiologic adaptation to starvation, some persist after recovery and might contribute to susceptibility to AN recurrence. In this Review, we summarize key endocrine alterations in AN, with a particular focus on the profound bone loss that can occur in this disease. Although AN is increasingly prevalent among boys and men, the disorder predominantly affects girls and women who are, therefore, the focus of this Review.