Back to ENDOCRINOLOGYAnorexia Nervosa is a chronic disorder characterized by self-induced weight loss, psychologically by body-image and other perceptual disturbances, and biologically by physiologic alterations that result from nutritional depletion.
The disorder afflicts predominantly white, young females (95 per cent). The disorder is associated with higher social class, occurring in up to 1 in 250 adolescents students in private schools.
1 - Sociocultural Factors
Social pressure from peers, particularly during adolescence seem to influence young women and girls to engage in anorectic behaviors. Although this factor in not sufficient for the disease to develop, it creates a proper environment for the expression of the disease in predisposed individual. Recent studies show an association between child abuse and anorexia, but it needs further study.
2 - Psychological Factors
Psychiatric interviews suggest that the patient develops within a family that values outward appearance, proper behavior, and achievement more than self-actualization. In response to the parents expectations, the pre-anorectic child learns to be hard working, eager to please, and attentive to family needs. However, the high standards within the family are rarely achieved by the child, who obsessively struggles for parental approval.
It follows that "negative" childhood behaviors are not permitted. The decision to diet, while not fully understood, may be a desperate attempt to control of one’s body, at least, in a distressing new environment.
3 - Biologic Factors
There is an increased incidence of anorexia nervosa among siblings(6%) with a four- to five-fold difference in concordance rates for monozigotic twins, suggesting predisposing genetic factors. Abnormalities in satiety, temperature regulation, and endocrine dysfunction suggest that a hypothalamic abnormality exists, although no specific lesion has been identified.
The disorder is a clinical entity, with no characteristic pathologic or physiologic finding.
1 - Psychological and Behavioral Features
Pursuit to thinness. Patients are not truly anorectic, but struggle against hunger to achieve an unrealistic degree of weight loss. For most anorectics, weight loss is accomplished through dietary restriction and exercise (restrictive group), although up to 50% will also self-induce vomiting or take purgatives (bulimic group).
Perceptual disturbances, insisting they are fat despite profound weight loss. They distort hunger awareness, deny fatigue, and fail to recognize emotional states such as anger and depression.
Sense of ineffectiveness
Cognitive deficits
2 - Physical Signs
Patinets may have severe loss of subcutaneous fat and exhibit bony prominences. Core temperature, blood pressure, and pulse rate are decreased. Other signs are acrocyanosis, downy hair, and a yellow discoloration of the skin. Secondary sexual features are absent in the patient who develop anorexia nervosa before puberty.
3 - Endocrine Abnormalities
Gonadal. It is the hallmark of the disease is gonadal dysfunction, and for women this presents as amenorrhea. Male anorectics lose libido and are infertile. The levels of FSH and LH are decreased and patients do not exhibit secretory bursts of LH throughout the day in response to endogenous LH-RF, indicating an abnormality in hypothalamic regulation. It may be caused by loss of body fat content or from psychological factors. Normal menses usually recur with body weight gain.
Thyroid. Signs of hypothyroidism such as decreased vital signs, dry skin, constipation, cold intolerance. T3 levels tend to be low, with higher level of reverse T3. Under the stress of malnutrition the liver preferentially deiodinates T4 to rT3. However, free thyroxin, total T4 levels, and the TSH response to TRH are normal. Treatment with exogenous thyroid hormone is not indicated.
Adrenal. Normal or slightly elevated plasma cortisol with decreased urinary excretion of 17-hydrocorticosteroids.
Growth hormone. Normal or slightly elevated with a decrease in somatomedin levels.
4 - Cardiovascular Abnormalities
Depressed cardiovascular function with a decreased cardiac O2 consumption, left ventricular wall thickness, cardiac chamber size, and blood pressure.
5 - Other Abnormalities
Leukopenia, anemia, thrombocytopenia, delayed gastric emptying, pancreatic fibrosis. Mal-absorptive diarrhea and acute gastric dilation may develop with rapid refeeding.
A. Refusal to maintain body weight over a minimal normal weight for age and height or failure to make expected weight gain during period of growth, leading to body weight 15% below that expected.
B. Intense fear of gaining weight or becoming fat, even though underweight.
C. Disturbance in the way in which one’s body weight , size or shape is experienced.
D. In females, absence of at least three menstrual cycles when otherwise expected to occur.
The differential diagnosis include: panhypopituitarism, Addison’s disease, diabetes mellitus, Chron’s disease, celiac sprue, tuberculosis, lymphoma.
The general approach should include: fostering a sense of autonomy in the patient by encouraging her to take personal responsibility in the treatment plan, remaining objective, consistent, and honest in order to maintain the patient trust, involving the family in the treatment plan.
Nutritional Care. Hospitalization is only required with severe malnutrition. The goal of enteral or parenteral supplementation is to slowly get the patient to a body weight out of range of medical risk.
Pharmacotherapy is of no proven value.
Psycotherapy is used to help the patient modify the aberrant eating behavior and to improve psychosocial function. Family therapy offers the best potential for long-term benefit.
1 - Wyngaarden, Cecil Textbook of Medicine.
2 - Greenspan, Basic and Clinical Endocrinology
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