Assessment of the relationship between serum thyroid hormone levels and peripheral metabolism in patients with anorexia nervosa

It has been observed that basal and/or TRH-stimulated serum TSH levels occasionally conflict with the actual values of circulating thyroid hormones in patients with anorexia nervosa. In the present study sixteen female patients with anorexia nervosa during self-induced starvation displayed clinical findings suggesting hypothyroidism, e.g., cold intolerance, constipation, bradycardia, hypothermia and hypercholesterolemia in association with decreased serum total T3 (62.8 +/- 5.2 ng/dl) and T4 (6.6 +/- 0.3 micrograms/dl). Markedly decreased T3 correlated positively with average heart rate (r = 0.5655, P less than 0.025) and negatively with total cholesterol (r = -0.7413, P less than 0.005). This result may suggest that peripheral metabolic state of the underweight anorexics depends considerably upon the serum T3 concentration. Despite decreased total thyroid hormones, free T4 assayed by radioimmunoassay was normal in all five cases examined (1.4 +/- 0.2 ng/dl) and the free T4 index in fifteen cases was normal except in one case. Basal TSH was not increased and TSH response to exogenous TRH was not exaggerated in any. These results may be compatible with a theory that free T4 has a dominant influence on pituitary TSH secretion. Furthermore, glucocorticoids may also have some influence on depressed TSH response, because an inverse correlation between increased plasma cortisol and the sum of net TSH increase after TRH was observed in twelve cases examined. In conclusion, it is suggested that normal sensitivity of peripheral tissues and pituitary thyrotroph to different circulating thyroid hormones is maintained in anorexia nervosa patients even during severe self-induced starvation, and that the metabolic state in these patients is considerably under the influence of circulating T3.     

Resting tachycardia, a warning sign in anorexia nervosa: case report

Background

Among psychiatric disorders, anorexia nervosa has the highest mortality rate. During an exacerbation of this illness, patients frequently present with nonspecific symptoms. Upon hospitalization, anorexia nervosa patients are often markedly bradycardic, which may be an adaptive response to progressive weight loss and negative energy balance. When anorexia nervosa patients manifest tachycardia, even heart rates in the 80–90 bpm range, a supervening acute illness should be suspected.

Case presentation

A 52-year old woman with longstanding anorexia nervosa was hospitalized due to progressive leg pain, weakness, and fatigue accompanied by marked weight loss. On physical examination she was cachectic but in no apparent distress. She had fine lanugo-type hair over her face and arms with an erythematous rash noted on her palms and left lower extremity. Her blood pressure was 96/50 mm Hg and resting heart rate was 106 bpm though she appeared euvolemic. Laboratory tests revealed anemia, mild leukocytosis, and hypoalbuminemia. She was initially treated with enteral feedings for an exacerbation of anorexia nervosa, but increasing leukocytosis without fever and worsening left leg pain prompted the diagnosis of an indolent left lower extremity cellulitis. With antibiotic therapy her heart rate decreased to 45 bpm despite minimal restoration of body weight.

Conclusions

Bradycardia is a characteristic feature of anorexia nervosa particularly with significant weight loss. When anorexia nervosa patients present with nonspecific symptoms, resting tachycardia should prompt a search for potentially life-threatening conditions.     

Evolutionary biology and psychiatry: The case of anorexia nervosa

A review of the literature and an analysis of 19 case histories suggest that evolutionary mechanisms such as reproductive suppression, kin selection, and parental manipulation are involved in the development of anorexia nervosa. From this perspective, anorexia nervosa is viewed as—in some cases—an adaptive feature of human reproductive strategies and may be best understood as an emergency strategy that is pursued whenever the sovereign handling of one's own reproductive potential is not possible because of socioecological or ontogenetic constraints.     

The role of selenium in thyroid hormone metabolism and effects of selenium deficiency on thyroid hormone and iodine metabolism

Selenium deficiency impairs thyroid hormone metabolism by inhibiting the synthesis and activity of the iodothyronine deiodinases, which convert thyroxine (T₄) to the more metabolically active 3,3′-5 triiodothyronine (T₃). Hepatic type I iodothyronine deiodinase, identified in partially purified cell fractions using affinity labeling with [¹²⁵I]N-bromoacetyl reverse triiodothyronine, is also labeled with⁷⁵Se by in vivo treatment of rats with⁷⁵Se-Na₂SeO₃. Thus, the type I iodothyronine 5′-deiodinase is a selenoenzyme. In rats, concurrent selenium and iodine deficiency produces greater increases in thyroid weight and plasma thyrotrophin than iodine deficiency alone. These results indicate that a concurrent selenium deficiency could be a major determinant of the severity of iodine deficiency.     

The role of selenium in thyroid hormone metabolism and effects of selenium deficiency on thyroid hormone and iodine metabolism

Selenium deficiency impairs thyroid hormone metabolism by inhibiting the synthesis and activity of the iodothyronine deiodinases, which convert thyroxine (T₄) to the more metabolically active 3,3′–5 triiodothyronine (T₃). Hepatic type I iodothyronine deiodinase, identified in partially purified cell fractions using affinity labeling with [¹²⁵I]N-bromoacetyl reverse triiodothyronine, is also labeled with⁷⁵Se by in vivo treatment of rats with⁷⁵Se−Na₂SeO₃. Thus, the type I iodothyronine 5′-deiodinase is a selenoenzyme. In rats, concurrent selenium and iodine deficiency produces greater increases in thyroid weight and plasma thyrotrophin than iodine deficiency alone. These results indicate that a concurrent selenium deficiency could be a major determinant of the severity of iodine deficiency.     

Angiotensin-converting enzyme and anorexia nervosa

Angiotensin-converting enzyme (ACE) activity was measured in 10 patients with anorexia nervosa, 6 with hyperthyroid Graves' disease, and 7 with primary hypothyroidism. Patients with anorexia nervosa had a low serum ACE activity (9.8 +/- 2.2 IU/l), as compared to findings in normal subjects (13.4 +/- 3.5 IU/l) (P less than 0.05). Patients with hyperthyroid Graves' disease had high serum ACE activity (23.7 +/- 5.8 IU/l), as compared to levels in normal subjects (P less than 0.01), and patients with primary hypothyroidism tended to have low serum ACE activity (10.1 +/- 1.8 IU/l), compared to the normal subjects (P less than 0.1). Following weight gain (before; 71.3 +/- 10.2% of ideal body weight, after; 88.7 +/- 5.6% of ideal body weight), serum ACE activity in patients with anorexia nervosa reverted to within the normal range (13.8 +/- 3.5 IU/l), and serum T3 concentration was restored to the normal range (before; 0.7 +/- 0.2 ng/ml, after; 1.1 +/- 0.3 ng/ml). In these patients, ACE activity correlated with the per cent of ideal body weight (P less than 0.05). These data suggest that, in underweight subjects with anorexia nervosa, decreased serum ACE activities may relate to emaciation.     

Iodide-induced hypothyroidism in a patient with anorexia nervosa

A 39-year-old woman who had been suffering from anorexia nervosa was found to have hypothyroidism. Serum T4, free T4, T3, free T3 and TSH were 3.19 micrograms/dl, 0.5 ng/dl, 15.3 ng/dl, 1.2 pg/ml and 162.1 microU/ml, respectively. On careful questioning, she was found to have taken an iodine-rich diet. The serum iodine concentration was 122 micrograms/dl (normal: 4-9 micrograms/dl) and urinary iodide excretion was 13.05 mg/day (normal: less than 2 mg). After withdrawal of the iodine-rich diet, her serum T4 gradually increased and TSH returned to the normal range. She was diagnosed as having iodide-induced hypothyroidism. However, no significant elevation of serum T3 or free T3 was observed. Serum T4, free T4, T3, free T3 and TSH were 7.85 micrograms/dl, 0.8 ng/dl, 13.6 ng/dl, 4.3 pg/ml and 6.02 microU/ml, respectively. The iodide-perchlorate discharge test result was negative. These findings suggest that there exists some unknown mechanism by which a patient with anorexia nervosa may be sensitive to excess iodide. Furthermore, it is of interest to note that in a recovery phase from the hypothyroid state, normalization of serum T4 rather than T3 is well-correlated to TSH secretion.     

Steroids and neuroendocrine function in anorexia nervosa

Anorexia nervosa is a primarily psychiatric syndrome of self-induced weight loss due to an intense fear of becoming obese. Numerous endocrine abnormalities occur in anorexia nervosa patients, and in many respects these alterations reflects the endocrinology of reduced energy intake. However, the basic mechanisms of those alterations are far from being understood. In an attempt to understand the disrupted mechanisms of the hypogonadotropic hypogonadism of the anorectic state, we studied 10 anorectic women in the acute phase of their illness; all met the DSM III criteria. On each patient, two tests were performed with either saline as control or infusion of the opioid antagonist naloxone, and both LH and FSH levels were measured. Four mg of naloxone as bolus was used, followed by a naloxone infusion of 2 mg/h for 4 h. Compared with the pattern of normal women, naloxone did not increase in the anorectic patients either LH or FSH levels nor pulsatility. This result suggests that endogenous opioid peptides are not implicated in the low gonadotropic situation of anorexia nervosa. An alternative explanation could be that the low estrogenic "milieu" of these patients could mask the opioid action. To test this second possibility, another group of 7 anorectic women after partial weight recovery were challenged with estrogen administration. Compared with the pattern of normal women volunteers, all the anorectic patients but one presented an abnormal response in both LH and FSH levels after estrogen administration. In fact, the negative feedback and the delayed positive feedback of LH after estrogen were absent in these patients. Interestingly enough, the only patient with near-normal LH response to estrogen was considered fully recovered by the Psychiatric Unit. Several alterations in the hypothalamic-pituitary-adrenal axis has been reported in anorexia nervosa. Seven anorectic patients and 7 aged-matched women were challenged by ACTH 1-24, 250 micrograms (i.v.) and the ratio of increments in adrenal steroid products to precursors monitored. ACTH-induced increments in cortisol with respect to increments in 17-OH-progesterone was similar in anorectics and controls. On the contrary, the ratio of increments of androstenedione with respect to increments in 17-OH-progesterone were greater in anorexia nervosa than controls. These results suggest that in anorexia nervosa the 11-beta-21-alpha-hydroxylase system is normal but a deficient 17-20 desmolase system is present. Finally, the altered pattern of GH secretion in anorexia was studied using GHRH (1 microgram/kg) as stimulus of pituitary GH secretion.(ABSTRACT TRUNCATED AT 400 WORDS)     

Compliance and outcome in anorexia nervosa.

Anorexia nervosa is notoriously difficult to treat, but little is known regarding the relationship of compliance to treatment outcome. We investigated in 41 adolescents who fulfilled DSM-III-R criteria for anorexia nervosa, the relationship between the completion of a standard psychosocial treatment program, subtypes of anorexia nervosa, and outcome as determined by standardized measurements. These adolescents were observed for an average of 32.4 months. Overall, 29 patients (70%) improved considerably, but 10 (24%) were symptomatic, and 2 (5%) remained in poor condition. There were no deaths. Of the 41 patients, 14 (34%) completed our entire treatment program, 15 (37%) received major treatment and failed in the outpatient follow-up phase only, 7 (17%) dropped out of inpatient treatment before its completion, and 5 (12%) refused treatment in our system altogether. Of all the dropouts, 10 received no further treatment. One patient was admitted to hospital elsewhere but again dropped out in the outpatient phase of that program. Seven patients (17%) received further outpatient treatment only, and 9 (22%) received inpatient and outpatient care and seemingly completed their treatment. Treatment completion significantly affected the measures of global clinical functioning and specific psychopathologic features, but only for those patients who completed the initial program. Bulimic patients did considerably worse on follow-up and were less likely to complete treatment. Patients with restricted anorexia nervosa were more likely to complete treatment than those with a bulimic subtype (P = .03). Differential compliance rates in the two subtypes confound the effects of treatment completion and need to be controlled for in future studies. Depression was not associated with noncompliance but, if present, was associated with poor outcome on follow-up and abated in only a third of those in whom it was initially present.     

Cold adaptation and thyroid hormone metabolism.

Resting oxygen consumption and energy expenditure is sensitive to slight alterations in thyroid function. This means that timing and magnitude of cold adaptation would to some extent depend on thyroid function. Local thyroid hormone metabolism is important for energy expenditure and dissipation of heat in special tissues. Recruitment of brown adipocytes and upregulation of uncoupling protein 1 in mitochondria depends on high tissue T3 concentrations. Most of this T3 is derived from local 5' deiodination of T4. Brown fat is vital for cold exposed mice and rats, and may be important for temperature adaptation in human neonates. The role of thyroid hormone metabolism in adult human cold adaptation has not been finally clarified. Hypothetically, cold exposure may enhance T3 production by deiodination of T4 in skeletal muscle, which may enhance heat production in muscle via a change in muscle fiber type. Another hypothetical possibility is recruitment of brown adipocytes embedded in white adipose tissue in human adults. Understanding cold adaptation in human adults may lead to development of new drugs against obesity.