Basics
Description
Anorexia nervosa (AN) is a complex biopsychosocial illness.
- Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) criteria:
- Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as weight that is less than minimally normal or, for children and adolescents, less than minimally expected.
- Intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight
- Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of current low body weight
- Types: Restricting (no binge eating or purging) or binge eating/purging (purging includes vomiting, laxatives and/or diuretic use)
- Reprinted with permission from the American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. American Psychiatric Association; 2013:171.
Epidemiology
Prevalence
- Approximately 0.5% of adolescent girls in the United States have AN.
- 10% of all patients with eating disorders are males.
- In younger patients, approximately equal numbers of females and males
- Increasing prevalence of eating disorders is seen in preadolescents, in males, and in minority populations within the United States.
Risk Factors
- Early physical/pubertal development
- Personality traits such as perfectionism and eagerness to please
- Family history of eating disorders, alcoholism, or mood disorders
- Involvement in sports or activities that emphasize shape/weight
- "Dieting" itself is a risk factor for developing an eating disorder.
Genetics
Family studies demonstrate that 1st-degree relatives have a 10-fold increased lifetime risk of developing AN. Twin studies also support role of genetics and familial concordance of AN.
General Prevention
- Assess height, weight, and BMI at every preventive visit at a minimum; evaluate for deviations.
- Discourage "dieting" behavior. Instead, focus on promoting healthy eating behaviors and lifestyle change.
- Strongly encourage regular family meals. Research supports this as a protective factor for all types of eating disorders and obesity.
Pathophysiology
- Physical manifestations are primarily the result of caloric restriction and consequences of malnutrition, which can affect all organ symptoms. The degree of symptoms seen may be due in part to the duration and severity of caloric restriction.
- Associated changes may also be due to purging, including vomiting, laxative use, or diet pill use.
- Bradycardia and hypothermia may result from significantly decreased metabolic rate due to malnutrition and caloric restriction.
- Hormonal changes due to starvation include resumption of prepubertal gonadotropin secretion.
Etiology
Evidence for specific etiology is not definitive; most likely multifactorial, including genetic risk factors, environmental triggers, and individual and family life experiences
Commonly Associated Conditions
- Amenorrhea
- Osteopenia/osteoporosis
- Female athlete triad (disordered eating, amenorrhea, osteoporosis)
- Depression
- Anxiety disorders including obsessive-compulsive disorder
- Substance abuse
Diagnosis
Diagnosis is made using DSM-5 criteria. However, many patients exhibit marked symptoms but do not meet the full criteria for AN; for example, despite drastic weight loss, the patient's weight remains in the normal range. These patients may be diagnosed with other specified feeding or eating disorder, also called subclinical or atypical anorexia nervosa. These patients likely still require close monitoring and potential intervention.
History
- Weight history: highest and lowest weight in last year; patient's "target weight" they were attempting to reach with restriction. Ask, "How often do you weigh yourself? What is the most you have weighed in past year? The least? What do you think of as your own ideal weight?"
- Psychological assessment: interviews with patient and parents, detailed history of body image concerns, obsession with weight and/or shape, developmental and family history, social and academic history, cognitive and personality traits, and premorbid and current level of functioning. Critical in establishing a diagnosis and developing a treatment plan.
- Other psychological symptoms: Assess mood and anxiety symptoms, suicidal ideation, substance use, and other risky or self-injurious behaviors.
- Diet and nutrition history: 24-hour dietary recall, history of binge eating, purging (including use of diuretics, laxatives, diet pills, or emetics), food restrictions, or calorie counting
- Exercise history: type, how much and intensity.
- Menstrual history: last menstrual period (LMP), weight at LMP, history of skipped periods
Physical Exam
- Vital signs, specifically orthostatic heart rates (HR) and blood pressures (to evaluate for vital sign instability that may be an indicator of severity and need for inpatient management), and temperature
- Weight, height, and BMI plotted in comparison to historical growth curve.
- HEENT: evaluate for signs of dehydration, dental exam for erosion due to purging
- CV: cardiac status
- GI: evaluate for pain, tenderness, organomegaly
- Derm: lanugo, Russell sign (callousing of the finger from self-induced purging), evidence of self-injurious behavior
- GU: Tanner staging for pubertal development
- Neurologic: complete exam including funduscopic exam to rule out brain tumor
Diagnostic Tests & Interpretation
Lab
- Serum electrolytes, BUN/creatinine, glucose: typically normal if patient is not purging
- Serum calcium, magnesium, phosphorous: May all be low. If hospitalized, follow phosphorous daily to assess for refeeding syndrome.
- TSH; if indicated, free T4, T3: to rule out thyroid disease. If abnormal, may be due solely to starvation.
- CBC with differential: Anemia may be present due to iron deficiency or chronic disease but may be falsely normal if patient is dehydrated; low WBC count is seen with malnutrition.
- ESR: generally low due to malnutrition
- AST, ALT: occasionally abnormal due to fatty liver
- β-hCG: Rule out pregnancy if amenorrheic.
- Urinalysis: Evaluate specific gravity to assess for dehydration or may have dilute urine if patients water load to falsely increase their weight.
- Consider EKG: may demonstrate bradycardia, prolonged QTc
- Patients amenorrheic for >6 months:
- Dual-energy x-ray absorptiometry (DEXA) scan: Evaluate bone density, risk of compression fracture, and bone loss. May be helpful motivator for treatment as may not be reversible.
- Serum LH, FSH, prolactin, if persistent amenorrhea with normal weight: LH and FSH will generally be low.
Differential Diagnosis
- Medical conditions such as
- Pregnancy
- Oncologic: brain tumor, other cancers
- GI: inflammatory bowel disease (including Crohn and ulcerative colitis), celiac disease
- Endocrinologic: diabetes mellitus, thyroid disease, hypopituitarism, Addison disease
- HIV or other chronic infections
- Psychiatric or psychological conditions such as
- Psychiatric: depression, obsessive-compulsive disorder, substance abuse, psychotic symptoms
- DSM-5 avoidant/restrictive food intake disorder: food aversions/hypersensitivity, extreme picky eating, decreased intake due to fears of swallowing/choking
Treatment
- Multidisciplinary team approach is considered the state of the art standard of care and includes medical monitoring, nutritional counseling, and psychological treatments.
- Family-based treatment (FBT) is the only evidence-based psychological treatment for pediatric and adolescent AN. Parents/caregivers are viewed as an integral part of the treatment team.
- Initially, all meals and snacks are prepared by and supervised by the parents. Gradually, age appropriate autonomy regarding eating is returned to the child/adolescent as physical and psychological progress is made.
Medication
- Medications are not the primary mechanism for treating AN but may be helpful in the treatment of co-occurring illnesses such as depression and anxiety.
- Medications to treat constipation may be necessary but should be used with caution.
- Supplements such as multivitamin, calcium, and vitamin D should be considered.
- Refeeding is the treatment of choice for amenorrhea rather than starting oral contraceptive pills (OCPs).
Issues for Referral
Depending on severity and availability, refer to an adolescent medicine specialist or other eating disorder specialist.
Inpatient Considerations
Admission Criteria
- Criteria for inpatient hospitalization:
- Severe malnutrition with weight <75% ideal body weight or weight loss despite treatment
- Bradycardia including daytime HR <50 bpm
- Nighttime HR <45 bpm
- Systolic blood pressure <90 mm Hg
- Orthostatic hypotension or significant orthostatic changes in pulse
- Severe hypothermia (temperature <96 °F)
- Arrhythmia
- Acute food refusal
- Severe electrolyte abnormalities.
- Suicidality may require psychiatric hospitalization.
Discharge Criteria
Once a patient is medically stable and no longer meets admission criteria, insurance companies may limit lengths of hospital stays. Most patients are treated solely as outpatients.
Ongoing Care
- Ongoing medical monitoring with emphasis placed on overall vital signs and not on weight alone
- Goals are set for nutritional rehabilitation. Meal plans are established and reassessed at each subsequent visit.
- Referral to a family therapist with this expertise is advised. Individual psychotherapy may be useful for many patients also particularly given the anxiety that is typically generated by the refeeding process.
- Group psychotherapy can be a useful adjunct particularly for some older adolescent patients.
- More intensive services include intensive outpatient, day, or residential treatment.
- Other adjunctive therapies include mindfulness training, expressive arts, etc.
Prognosis
- Most adolescent patients recover fully but generally not without a long course of treatment. Overall, children and adolescents have better outcomes than adults.
- Better outcomes are associated with shorter duration of symptoms, earlier diagnosis, absence of purging behaviors, and less severity of psychiatric comorbidity. However, outcome findings vary depending on factors such as length of follow-up and definitions of recovery.
- Mortality rates for adolescents with AN are reported to be 1.8%, primarily from effects of starvation or from suicide.
Complications
- Majority of complications may be reversed with improved nutrition.
- Refeeding syndrome: As the patient is refed, the body may shift from a catabolic state to an anabolic state, resulting in a release of insulin which may drive phosphorous and potassium intercellularly and drop extracellular levels resulting in delirium, coma, arrhythmias, cardiac failure, and death.
- CV: arrhythmias, pericardial effusions
- GI: delayed gastric emptying, slowed intestinal motility and constipation, pancreatitis; elevated cholesterol
- Endocrine: amenorrhea, osteoporosis, sick euthyroid syndrome, growth delay
- Complications related to purging include Mallory-Weiss tears, esophagitis, electrolyte and fluid imbalances (particularly hypokalemia)
- Neuropsychological: anxiety, poor concentration, depressed mood, cognitive impairment, cortical atrophy
Additional Reading
- Academy for Eating Disorders. Eating disorders. AED Report 2012. 2nd ed. www.aedweb.org. Accessed March 11, 2015.
- American Psychiatric Association. Guideline Watch (August 2012): Practice Guideline for the Treatment of Patients with Eating Disorders. 3rd ed. http://psychiatryonline.org. Accessed March 11, 2015.
- Rosen DS; American Academy of Pediatrics Committee on Adolescence. Identification and management of eating disorders in children and adolescents. Pediatrics. 2010;126(6):1240-1253. [View Abstract]
- Silber T. Anorexia nervosa in children and adolescents: diagnosis, treatment and the role of the pediatrician. Minerva Pediatrica. 2013;65(1):1-17. [View Abstract]
- Trace E, Baker JH, Pe ħas-Lled ³ E, et al. Genetics of eating disorders. Annu Rev Clin. 2013;9:589-620. [View Abstract]
See Also
- National Eating Disorders Association (www.nationaleatingdisorders.org)
- Maudsleyparents.org; FEASTED.org
- Bulimia chapter
Codes
ICD09
- 307.1 Anorexia nervosa
- 307.59 Other disorders of eating
ICD10
- F50.00 Anorexia nervosa, unspecified
- F50.01 Anorexia nervosa, restricting type
- F50.02 Anorexia nervosa, binge eating/purging type
- F50.8 Other eating disorders
SNOMED
- 56882008 Anorexia nervosa (disorder)
- 77675002 Anorexia nervosa, restricting type
- 63393005 Anorexia nervosa, binge-eating purging type
- 72366004 Eating disorder (disorder)
FAQ
- Q: If the patient presents with severe low mood, why not start them on an antidepressant right away?
- A: Many of their depressive symptoms may be secondary to the effects of their malnourished state. It's best to begin nutritional rehabilitation and reassess as intake improves.
- Q: Can patients have AN if they do not report feeling fat or intentionally dieting?
- A: Yes. Denial is very often associated with AN. Rely on behavioral signs and parental report.
- Q: Can AN be diagnosed in preadolescents?
- A: Yes. The age of onset of AN has continued to decrease. If they present with weight preoccupation, pursuit of thinness, and other diagnostic criteria, their diagnosis is AN.