Anorexia nervosa

*Anorexia nervosa* is an eating disorder marked by self-induced starvation and severe weight loss. Patients relentlessly restrict calories, leading to a significantly low body weight for their age/height. There is an intense fear of gaining weight and a distorted body image (they see themselves as overweight despite being underweight).

• This disorder typically affects adolescent females (median onset ~18 years), with a lifetime prevalence around 0.3–0.9% in women. It has one of the *highest mortality rates* of any psychiatric illness (on the order of 5–20% over 10–20 years, often from medical complications or suicide). Chronic anorexia causes multi-system injury: cardiac (arrhythmias, cardiomyopathy), endocrine (amenorrhea, osteoporosis), hematologic (anemia), and neurological damage. Early recognition and treatment are crucial to prevent life-threatening consequences.

• Underweight adolescent (often female) who restricts diet and exercises excessively; denies severity of illness. Key features: BMI <18 (adult) or <5th percentile (child).
• Physical exam: bradycardia (HR<50) and hypotension, cold extremities, dry skin, muscle wasting, and lanugo (fine body hair). In females, amenorrhea (no menses) is common (though not required for diagnosis).
• Behavioral: extreme preoccupation with weight/fat and distorted body image. They often count calories or purge (vomiting/laxatives) without maintenance of normal weight.
• Lab clues: hypokalemia (if vomiting/purging), metabolic alkalosis or acidosis (vomiting/laxative use), anemia or leukopenia from malnutrition. ECG may show QT prolongation or arrhythmias.

1. Confirm diagnosis by history and exam: check BMI <18.5 (adult) or <percentile (child) plus intense fear of weight gain and body image distortion.
2. Obtain labs and ECG: CBC, metabolic panel (electrolytes, glucose, LFTs), TSH, and pregnancy test (in females), plus ECG for QT interval.
3. Exclude medical causes of weight loss (e.g. GI malabsorption, hyperthyroidism) through targeted history and lab testing.
4. Assess medical stability: frequent vital signs (HR, BP, orthostatics), electrolytes, and mental status. If unstable (e.g. HR<40, hypotension, arrhythmia, suicidal), hospitalize and start controlled refeeding.
5. For stable patients, develop outpatient plan: supervised meal plan or day program, with regular follow-up. Engage a multidisciplinary team including nutritionist and therapist.

1. Nutritional rehabilitation: Gradually increase caloric intake (start low and go slow), with monitoring for refeeding syndrome (phosphate, K⁺, thiamine). Hospitalize if needed for IV support.
2. Psychotherapy: Adolescents — Family-Based Therapy (Maudsley approach) is first-line. Adults — Eating-disorder-focused CBT (CBT-ED/CBT-E) or MANTRA/SSCM therapy.
3. Medications: No FDA-approved drugs for core anorexia. Low-dose olanzapine can aid weight gain, and SSRIs may be used for comorbid depression after weight restoration. (Avoid bupropion due to seizure risk.)
4. Address complications: Supplement vitamins/minerals (Ca/Vit D for bone, etc.), monitor bone density. Involve nutritionist and regular medical monitoring (glucose, bone health).
5. Admission criteria: Severe malnutrition (BMI <75% ideal), bradycardia (<40–50 bpm), hypotension, hypokalemia, or suicidality require inpatient care.

• If BMI is low and fear of weight gain is present, think anorexia; if BMI is normal with binge/purge behaviors, think bulimia.
• DSM-5 tip: *Amenorrhea is not required* for diagnosis. Severity is graded by BMI (mild ≥17, moderate 16–16.9, severe 15–15.9, extreme <15).
• During refeeding, watch *phosphate*: administering carbs drives intracellular phosphate shift, risking hypophosphatemia.

• Sinus bradycardia (HR <50–60 bpm) or hypotension (signs of severe malnutrition)
• Lanugo (fine body hair), hypothermia, and extreme weight loss
• Amenorrhea in postpubertal females
• Electrolyte disturbances (esp. hypokalemia, hypophosphatemia) and prolonged QT → risk of fatal arrhythmias
• Suicidal ideation or attempts (elevated in anorexia) and osteoporosis (fracture risk)

1. Suspect anorexia in a patient with significant weight loss and fear of gaining weight; measure BMI to confirm underweight.
2. Take detailed history: diet, exercise, purging behaviors, body image. Perform physical exam (vitals, lanugo, signs of malnutrition).
3. Order labs and ECG: CBC, electrolytes (K⁺, PO₄), glucose, LFTs, TSH, and pregnancy test, plus ECG for QT interval.
4. If BMI <15 or any instability (bradycardia, hypotension, arrhythmia, severe hypokalemia): hospitalize for medical stabilization and controlled refeeding.
5. If stable (BMI ≥15, normal vitals): outpatient management with structured meal plan and psychotherapy (FT-AN for <18, CBT-ED for adults).
6. Monitor weight gain, vital signs, and electrolytes closely; adjust treatment level if patient deteriorates or fails to progress.

• 15-year-old F with 6 months of weight loss, BMI 15 kg/m², pulse 45, dry skin, amenorrhea; denies concern about weight (→ anorexia nervosa).
• 20-year-old college student with BMI 17, intense exercise and 800 kcal/day diet, cold intolerance, and lanugo hair (→ anorexia nervosa).
• 25-year-old male with BMI 17, compulsive exercise, fear of fatness, bradycardia (HR 52) and hypokalemia (K⁺ 3.0) on labs (→ anorexia nervosa).