History and exam
Key diagnostic factors
common
significantly low body weight
While there is no single definition of low weight, adults with anorexia nervosa commonly present with body mass index (BMI) <18.5 kg/m².
For children and adolescents, BMI below the 5th percentile for age commonly indicates low weight, although low weight determinations should be made in the context of an individual’s build and growth trajectory. A BMI of <13 kg/m² in an adult, and BMI less than 70% of the predicted BMI for age in a child, indicates an impending risk to life. Note that the rate of weight loss is also important; loss of >1 kg per week for 2 consecutive weeks indicates particular cause for concern.[67]
fear of gaining weight or becoming fat, or behaviors that interfere with weight gain despite evidence of significantly low body weight
Patients may speak of their belief that they are fat, or fear that they will become fat; alternatively, they may believe that their presenting low weight is "fine," and that weight gain is not indicated because it would bring them to an excessively high weight.
Patients may instead say that they know their weight is low and that weight gain is indicated. For these individuals, it is important to determine whether their behaviors may indicate reluctance about, or interference with, weight restoration. Such behaviors may include avoidant or secretive eating, excessive exercise, and purging behaviors.
Patients will commonly express reluctance about weight gain interventions.
disturbed body image
Patients are unduly influenced by thoughts of body shape and weight.[1] They may experience cognitive distortions about their body's actual size and shape. They may experience certain body parts as excessively large, may engage in behaviors that repeatedly check body part sizes, and commonly fail to acknowledge overall thinness.
calorie restriction
Individuals with anorexia nervosa (AN) have restricted calorie intake, relative to requirements.[1] Total daily caloric ingestion may be exceedingly low (e.g., 300-700 kcal) in someone with AN, commonly achieved by avoiding dietary fats. Acute refusal or estimated calorie intake <500 kcal/day for 2 or more days may be considered a red flag feature in the risk assessment for AN.[67]
binge-eating and/or purging
All individuals with anorexia nervosa (AN) should be asked about binge-eating and purging behaviors; affected individuals may not choose to reveal these symptoms of illness.
Patients with AN may have subjectively defined binge-eating episodes, meaning that they experience loss of control when eating food quantities that are not objectively large.
Any pattern of binge-eating or purging for the previous 3 months is considered indicative of binge-eating and/or purging subtype.[1]
Physical signs of dental erosion due to acid exposure may be present in individuals with regular vomiting behavior.
Calluses or abrasions may be seen on the dorsal side of the hand if vomiting is regularly associated with manual trigger of gag reflex.
misuse of laxatives, diuretics, or diet pills
May be associated with binge-eating and/or purging subtype.[1]
amenorrhea
Amenorrhea is commonly seen in low weight girls and women with anorexia nervosa (AN).[70] Younger patients may have primary amenorrhea, and may not be aware that their low weight state has contributed to hypogonadal activity. Additionally, patients taking oral contraceptives may not consider themselves to be as seriously affected by AN because they have not experienced frank amenorrhea. Psychoeducation about the risks of low weight should be offered, including the risk of bone loss in AN, even among those who are taking orally administered hormones (i.e., oral contraceptive pills).
decreased subcutaneous fat
Many patients with anorexia nervosa appear cachectic on physical exam due to lack of body fat; bony structures such as collar bones, vertebrae, coccyx, and iliac crest may protrude dramatically.[66]
Other diagnostic factors
common
general fatigue, muscle weakness, and poor concentration
Specifically related to nutritional restriction and/or purging.[66]
Patients may report that they are no longer interested in reading or watching a movie and, on closer questioning, acknowledge greater difficulty with attention and focus.
Reduced muscle function may be demonstrated by a score <3 in either component in the Sit Up-Stand-Squat (SUSS) test; a score of 1 or less in either component of the SUSS test is considered a red flag feature in anorexia nervosa, and a score of 2 is considered an amber flag feature.[67]
significant preoccupation with thoughts of food
May occur despite the behavioral avoidance of food seen in many individuals with anorexia nervosa.
Patients may spend time reading menus, recipes, or nutritional information.
orthostatic hypotension
Low fluid status may result in slow re-equilibration from sitting to standing.[66]
May lead to dizziness or frank syncope.[66]
May result from hypovolemia and/or bradycardia and/or low cardiac output.
Orthostatic hypotension with recurrent syncope is a particular cause for concern and is typically seen in conjunction with echocardiogram abnormalities for as long as malnutrition persists.[67]
nonspecific gastrointestinal symptoms
Patients often report fullness, bloating, cramping gas, and constipation.[66]
These likely result from slowed gastric emptying associated with anorexia nervosa and improve with refeeding and weight restoration.
cardiac symptoms and signs
Bradycardia is the most common cardiac feature.
Other abnormalities include QTc prolongation, first-degree atrioventricular heart block, and, especially among individuals with electrolyte disturbances, nonspecific T-wave changes.
High risk features on ECG include prolonged QTc (<18 years: males >450 ms, females >460 ms; ≥18 years: males >430 ms, females >450 ms), heart rate <40 bpm, and arrhythmia associated with malnutrition and/or electrolyte disturbances.[67]
Mitral valve prolapse has also been described, likely related to the anatomic changes that occur in anorexia nervosa, including decreased cardiac muscle and visceral fat mass.
Pericardial effusions are seen infrequently.
changes to hair, skin, and nails
These occur within the context of malnutrition.[66]
Lanugo may appear on the face, trunk, and arms. Dry skin and cracked nails may also develop.
Hair thinning can occur, and may motivate the patient to improve nutritional status.
uncommon
dependent edema
This may occur especially during the process of refeeding.
Usually transient, and quick to resolve during refeeding.
Significant edema indicates a need for careful monitoring for signs and symptoms of refeeding syndrome.
osteopenia or osteoporosis
More likely to occur in individuals who have been ill for several years.
Young people who present with stress fractures and/or low bone density on dual-energy x-ray absorptiometry scans should be carefully evaluated for eating and nutritional status.
Risk factors
strong
female sex
adolescence and puberty
The risk of onset for AN is highest in late adolescence, with 40% of new illness occurring in patients between ages 15 and 19 years.[13][17][18] The risk of developing AN drops significantly after 21 years, although the menopausal period has been suggested as an additional high-risk period in women for the onset or recurrence of an eating disorder.[23][24]
Onset before 15 years is associated with greater illness severity and higher rates of lifetime psychiatric comorbidity.[20]
obsessive and perfectionist traits
Strongly linked to AN in case-study research.
Nonspecific risk for developing both AN and bulimia nervosa.[41]
exposure to Western media
Cross-cultural studies have linked increases in eating disorders to Western media exposure and ideals, and there is evidence that attitudes that may increase risk for eating disorders are increasing in non-Western countries.[9] Of note, rates of anorexia within Asian countries have increased substantially since 2000; rates within the past decade are now comparable to those seen in Western countries.[9][10][11][12]Although very few individuals who diet in an attempt to lose weight develop AN, the illness occurs more frequently in cultures where pursuit of thinness is prized.
genetic influence
An examination of eating disorders identified in a large Swedish national twin sample described heritability estimates of 57% in AN, indicating a substantial contribution of genetic factors to the condition.[38]
weak
middle and upper socioeconomic classes
athlete
appearance-related teasing
childhood maltreatment
Associated with unhealthy weight control behaviors, chronic dieting, and weight and shape concerns.[48]
celiac disease
Celiac disease diagnosed in childhood is associated with a 1.34-fold increased risk of developing an eating disorder.[49]
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