Emergent Management of Anorexia Nervosa 

Anorexia nervosa (AN) is a psychiatric disorder with severe physiologic consequences, characterized by the inability or refusal to maintain a minimally normal weight. Patients have a profoundly disturbed body image as well as an intense fear of weight gain despite being moderately to severely underweight.^[1]

Diagnostic criteria for anorexia nervosa in the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) include the following^[2] :

• A refusal to maintain body weight at or above a minimally normal weight for age and height (usually less than 85% of ideal body weight)
• Intense fear of gaining weight or becoming fat
• Disturbance in the way one's body weight or shape is experienced, with denial of current low body weight
• Amenorrhea in postmenarchal females of at least 3 menstrual cycles

Anorexia nervosa may be further divided into 2 subtypes: (1) restricting, in which severe limitation of food intake is the primary means to weight loss, and (2) binge-eating/purging type, in which there are periods of food intake that are compensated by self-induced vomiting, laxative or diuretic abuse, and/or excessive exercise.

Formal recommendations have been made to remove the amenorrhea criterion and the subtype distinctions from the criteria for anorexia nervosa in the upcoming DSM-V.^[3] In addition, numerous studies have demonstrated subthreshold eating disorders either alone or coexistent with other psychiatric diagnoses, suggesting the diagnostic criteria may need to be expanded, and there may be a higher prevalence of anorexia nervosa than previously thought.^[4]

Patients may or may not carry a diagnosis of anorexia nervosa when presenting to an emergency department for acute care, and other physiologic causes of malnutrition, weight loss, and amenorrhea must be ruled out before making the diagnosis.

Patients with anorexia nervosa often display other personality traits such as a desire for perfection, academic success, lack of age-appropriate sexual activity, and a denial of hunger in the face of starvation. Psychiatric characteristics include excessive dependency needs, developmental immaturity, social isolation, obsessive-compulsive behavior, and constriction of affect. Many patients also have comorbid mood disorders, with depression and dysthymic disorder being most prevalent.^{[5, 6, 7]}

Go to Pediatric Anorexia Nervosa for complete information on this topic.

Anorexia nervosa is the result of a complex interplay between biological, psychological, and social factors, which tend to affect women more than men, and adolescents more than older women. Some evidence suggests a higher rate of the disorder in monozygotic twins than in dizygotic twins, which may indicate a biologic predisposition.^[8]

Psychologically, prepubescent patients who subsequently develop anorexia nervosa have a high incidence of premorbid anxiety disorders. The onset of the disorder during puberty has led to the theory that, by exerting control over food intake and body weight, adolescents are attempting to compensate for a lack of autonomy and selfhood.

Individuals with anorexia nervosa maintain a lifelong increased incidence of anxiety, depressive disorders, and obsessive-compulsive disorder. Neurobiologists hypothesize that disruption of serotonergic pathways in the brain mediate the development of anorexia nervosa and may account for the frequent coexistence of other psychological disturbances.^[9]

The patient's altered body image results in a perception of fatness despite being normal or underweight. Attempts to correct this flaw through food restriction or purging lead to progressive malnutrition and eventually starvation. Modern preoccupation with slenderness and beauty in the Western world may contribute to the mindset of thinness as a valued quality in adolescents; however, this link has not been proven. A subset of adolescents who are temperamentally incapable of dealing with age-appropriate challenges without extreme reward-seeking behavior (thinness) may be susceptible to anorexia nervosa.^[10]

Malnutrition subsequent to self-starvation leads to protein deficiency and disruption of multiple organ systems. In addition to hypoglycemia and vitamin deficiencies, starvation results in release of endogenous opioids, hypercortisolemia, and thyroid function suppression.

Neuroendocrine disturbances result in delayed puberty, amenorrhea, anovulation, low estrogen states, increased growth hormone, decreased antidiuretic hormone, hypercarotenemia, and hypothermia.^[11] Decreased gonadotropin levels and hypogonadism may occur among males who are affected.

Cardiovascular effects include mitral valve prolapse, supraventricular and ventricular dysrhythmias, long QT syndrome, bradycardia, orthostatic hypotension, and shock due to congestive heart failure.^{[12, 13]}

Renal disturbances include decreased glomerular filtration rate (GFR), elevated blood urea nitrogen (BUN), edema, acidosis with dehydration, hypokalemia, hypochloremic alkalosis with vomiting, and hyperaldosteronism.

Gastrointestinal findings include constipation, delayed gastric emptying, and gastric dilation and rupture when binge eating. Patients who induce vomiting develop dental enamel erosion, palatal trauma, enlarged parotids, esophagitis, Mallory-Weiss lesions, and elevated transaminase levels. Cases of superior mesenteric artery (SMA) syndrome from loss of intraperitoneal fat in AN as well as gastric rupture from bingeing and purging, leading to pneumothorax and pneumoperitoneum, have been reported.^{[14, 15]}

Anorexia nervosa is a complex combination of biological, psychological, and social factors, which have devastating physical and mental consequences.

Twin studies suggest there is a 50-80% genetic contribution, which, when combined with a high-risk environment, predisposes to the development of anorexia nervosa. This places anorexia nervosa with a similar heritability estimate to that of bipolar disorder and schizophrenia.

A psychological profile often demonstrates premorbid anxiety disorders as well as more severe affective disorders such as major depression and dysthymic disorder. Patients may also have symptoms of obsessive-compulsive disorder, with rigid and ritualistic eating behaviors.

The lifetime prevalence of anorexia nervosa in the United States is estimated at 0.3-1%; however, some studies have shown rates as high as 4% among women. The rates among men are estimated at 0.1%. As many as 5% of young women exhibit symptoms of anorexia but do not meet full diagnostic criteria, and some studies show disordered eating behavior in 13% of adolescent girls in the United States.^{[5, 6, 7, 16, 17]}

Internationally, anorexia nervosa is found in all developed countries and in all socioeconomic classes at similar rates (0.3-1% in women, 0.1% in men) as well as in developing countries such as China and Brazil.^[7]

Racial, sexual, and age-related differences in incidence

Anorexia nervosa is significantly more frequent in white populations than in people of other races, but it has been reported among all races. A link between socioeconomic class and prevalence of eating disorders has not been demonstrated in the literature.

Female-to-male ratio is 10-20:1 in developed countries. In some professions, the frequency is much higher among men (wrestling, running, modeling) than the general male population.

Anorexia nervosa has been observed in both the very young and very old, but the disorder is primarily a phenomenon of puberty and early adulthood. Eighty-five percent of patients have onset of the disorder between the ages of 13 and 18 years.^{[5, 16, 17, 18]} Patients who are older at the time of onset of the disorder have a worse prognosis.

The prognosis for recovery from anorexia nervosa is multi-factorial. Overall, the prognosis has not changed much over the past 50 years.^{[1, 19]} Approximately 50% of patients will recover with treatment and maintain a normal weight but often not without relapses and with the aid of multiple treatment modalities.

In one large meta-analysis, 47% of patients fully recovered; 33% improved somewhat; and 20% developed chronic, relapsing anorexia.^[20] Patients with later age at onset of the disorder, binge-purge behavior, and concurrent mood disorders have a worse prognosis for full recovery.

Anorexia nervosa has one of the highest mortality rates of all psychiatric disorders, with rates reported from 4-18%.^{[16, 20, 21]} Patients with restricting subtype tend to be more refractory to treatment and are at high risk of death.^[22] Mortality is often due to suicide and less frequently due to complications of starvation.^{[20, 21]}

For patient education information, see the Eating Disorders Center and Women's Health Center, as well as Anorexia Nervosa and Amenorrhea.

Other useful sources of patient information are as follows:

• National Association of Anorexia Nervosa and Associated Disorders (ANAD)
• National Eating Disorders Association (NEDA)