Anorexia nervosa (AN) carries the highest mortality rate among psychiatric conditions, with a 5- to 6-fold increased risk of death relative to age-matched controls; approximately one-third of deaths are attributed to cardiovascular complications. [1-2] Every organ system is affected by the hypometabolic state of starvation, and complications accumulate over time. [3]
1. History
- Duration and severity of caloric restriction; specific foods avoided; rules about eating [4]
- Purging behaviors: self-induced vomiting, laxative/diuretic/enema misuse, excessive exercise [5]
- Weight trajectory: rate of loss, lowest weight, premorbid weight
- Menstrual history: oligomenorrhea/amenorrhea (present in ~78% of females with AN) [5]
- Binge eating episodes, loss of control while eating
- Exercise patterns: compulsive, exercising despite injury or illness [5]
- Body checking behaviors: frequent weighing, mirror checking, measuring body parts [4]
- Cognitive symptoms: difficulty concentrating, cognitive rigidity [4]
- Psychiatric comorbidities: depression, anxiety (~40.5% lifetime prevalence), OCD, trauma, substance use [5]
- Suicidal ideation or self-harm (suicide attempt prevalence ~24.9%) [5]
2. Alarm Features
- HR <50 bpm daytime or <45 bpm at night [6]
- BP <90/45 mmHg [6]
- Hypothermia (body temp <96°F / 35.6°C) [6]
- Orthostatic changes: pulse increase >20 bpm or SBP drop >20 mmHg or DBP drop >10 mmHg [6]
- QTc prolongation (>440 ms) — risk of lethal arrhythmia [6]
- Severe electrolyte derangements: hypokalemia, hyponatremia, hypophosphatemia [6]
- Syncope, seizures, cardiac failure, pancreatitis [6]
- Hypoglycemia [3]
- Acute suicidal ideation [6]
- BMI ≤15 in adults or ≤75% median BMI for age/sex in adolescents [4][6]
- Acute food refusal [6]
- Signs of refeeding syndrome during nutritional rehabilitation (tachycardia, tachypnea, edema, precipitous phosphate drop) [7-8]
3. Medications
Medication contributors to complications
- QTc-prolonging medications (antipsychotics, certain SSRIs, ondansetron, macrolides) — compounded risk with existing QTc prolongation and hypokalemia [6][9]
- Bupropion is contraindicated in patients with purging behaviors (seizure risk) [10]
- Laxatives → hyperchloremic metabolic acidosis, hypocalcemia, laxative dependence [6]
- Diuretics → volume depletion, electrolyte disturbances [3]
- Diet pills/stimulants → cardiac arrhythmia risk
Treatment medications
- Psychotropic medications are generally ineffective for weight gain in AN [4]
- SSRIs may address comorbid anxiety/depression but do not improve weight restoration [10]
- Olanzapine may have modest benefit but is limited by adverse effects [10]
- Hormonal treatments (estrogen, OCPs) do not improve weight gain or bone density reliably [10]
Refeeding prophylaxis
- Thiamine 100 mg before initiating feeding or dextrose-containing IV fluids, continued for 5–7 days [11]
- Multivitamin supplementation for ≥10 days [11]
- Prophylactic electrolyte repletion (K⁺, Mg²⁺, PO₄³⁻) if levels are low [8][12]
4. Diet
Acute refeeding
- Initial caloric target: 1,500–2,000 kcal/day, with incremental increases to 3,000–4,000 kcal/day until target weight is reached [5]
- Recent evidence supports higher initial caloric prescriptions (2,200–2,600 kcal/day) in mildly/moderately malnourished adolescents with monitoring [6]
- More cautious approach warranted in severely malnourished patients (<70% median BMI) [6]
- Avoid excess sodium and fluid in early refeeding (<1 mmol/kg/day Na⁺, <20 mL/kg/day fluid) [8]
Long-term
- Gradual normalization of eating patterns with dietitian guidance
- Caloric intake reduced to maintenance levels once target weight is achieved [5]
- Address food avoidance patterns (fats, calorie-dense foods) [4]
Hydration
- Correct dehydration carefully; avoid rapid IV fluid boluses in severely malnourished patients
- Monitor for edema during refeeding [6]
5. Review of Systems
- Cardiovascular: palpitations, chest pain, lightheadedness, syncope, exercise intolerance
- GI: early satiety, bloating, constipation, abdominal pain, GERD, vomiting blood (Mallory-Weiss)
- Neuro: difficulty concentrating, dizziness, peripheral numbness/tingling, seizures [3-4]
- MSK: bone pain, fractures, proximal muscle weakness, difficulty standing from sitting [4]
- Endocrine: amenorrhea, cold intolerance, hair loss, fatigue
- Derm: dry skin, brittle hair, lanugo [3]
- Psych: mood changes, anxiety, obsessive thoughts about food/weight, suicidal ideation [5]
- Renal: decreased urine output, flank pain (renal calculi) [3]
- Dental: tooth sensitivity, enamel erosion (purging subtype) [5]
6. Collateral History and Family History
- Collateral from family/friends is essential — patients frequently minimize or deny symptoms [5]
- Parental observations: food restriction, mealtime behaviors, exercise patterns, mood changes, social withdrawal
- Family history of eating disorders, depression, anxiety, OCD, substance use disorders
- Family history of autoimmune disease (celiac, thyroid disease) to exclude organic mimics
- Social context: academic pressure, athletic participation (especially sports emphasizing leanness), bullying, social media influence
- History of trauma or abuse
7. Risk Factors
- Female sex (though increasingly recognized in males)
- Adolescence and young adulthood (peak onset)
- Family history of eating disorders or psychiatric illness [5]
- Perfectionism, high achievement orientation, cognitive rigidity [4]
- Participation in sports/activities emphasizing thinness (gymnastics, ballet, wrestling, distance running)
- History of dieting or weight-related teasing
- Comorbid anxiety, depression, OCD [5]
- Type 1 diabetes mellitus ("diabulimia") [6]
- History of trauma or adverse childhood experiences
8. Differential Diagnosis
Cannot-miss diagnoses
- Hyperthyroidism — weight loss with tachycardia, tremor, heat intolerance (opposite vital sign pattern to AN)
- Malignancy — lymphoma, GI cancers causing weight loss, night sweats, lymphadenopathy
- Addison disease — weight loss, hypotension, hyperpigmentation, electrolyte abnormalities
- Type 1 diabetes — weight loss with polyuria, polydipsia
Important mimics
- Inflammatory bowel disease (Crohn disease) — abdominal pain, diarrhea, growth failure [5]
- Celiac disease — malabsorption, weight loss, may coexist with AN [6]
- Superior mesenteric artery syndrome — can be both a complication and a mimic [6]
- CNS lesion (hypothalamic/pituitary tumor) — weight loss, endocrine dysfunction
Other eating disorders
- Bulimia nervosa (normal/above-normal weight with binge-purge cycles) [5]
- Avoidant/restrictive food intake disorder (ARFID) — food avoidance without body image distortion
- Atypical anorexia nervosa — significant weight loss with psychological features of AN but BMI in normal/overweight range [5]
9. Past Medical History
- Previous episodes of AN or other eating disorders (high relapse rate; ~40% require repeated hospitalizations) [1]
- Prior hospitalizations for medical stabilization
- History of fractures (osteoporosis-related)
- Amenorrhea duration and reproductive history
- Renal function decline (end-stage renal disease in 5.2% at 21-year follow-up in one study) [4]
- Psychiatric treatment history: medications tried, therapy modalities
- Surgical history (especially GI)
- Comorbid chronic illness: diabetes, autoimmune conditions
10. Physical Exam
Vital signs
- Bradycardia (sinus, can be severe; HR may drop further during sleep) [4]
- Hypotension, especially orthostatic [5]
- Hypothermia [5]
- Orthostatic vital signs are mandatory per APA/AAP/SAHM guidelines [5]
General
- Cachexia, temporal wasting, prominent bony landmarks
- Lanugo (fine downy hair on face, neck, arms) [5]
- Dry, scaly skin; brittle hair with scalp hair loss [3]
- Peripheral edema (hypoalbuminemia or refeeding) [4]
HEENT
- Dental enamel erosion on lingual surfaces (purging subtype) [5]
- Parotid/salivary gland hypertrophy (purging subtype) [4]
- Poor dentition, dental caries [3]
Cardiovascular
- Bradycardia, irregular rhythm
- Poor peripheral perfusion, acrocyanosis [6]
- Mitral valve prolapse murmur (functional, from decreased LV mass) [2][6]
Extremities
- Muscle wasting, proximal weakness
- Russell sign (calluses on dorsum of hand from self-induced vomiting)
- Peripheral edema
Neurologic
- Peripheral neuropathy [3]
- Cognitive slowing
11. Lab Studies
Recommended initial labs (per APA/AAP/SAHM guidelines): [5-6]
- CBC with differential: leukopenia (with relative lymphocytosis), mild anemia, thrombocytopenia; depressed ESR [6][13]
- BMP: hypokalemia, hyponatremia, hypochloremia, elevated bicarbonate (vomiting) or metabolic acidosis (laxative abuse) [13]
- Phosphorus: decreased (critical to monitor during refeeding) [13]
- Magnesium: decreased [13]
- Calcium: usually normal [4]
- Glucose: hypoglycemia [3]
- Albumin/prealbumin: decreased [4]
- Hepatic panel: elevated transaminases; liver failure in severe cases [3][13]
- BUN/Cr: elevated BUN from dehydration; declining GFR over time [4][13]
- Cholesterol: often elevated (hypercholesterolemia) [13]
- Amylase: elevated (especially with purging) [4]
- Thyroid function: low T₃, elevated reverse T₃, low-normal T₄ (sick euthyroid) [13]
- Reproductive hormones (if amenorrhea): low LH, FSH, estradiol [5]
- Urinalysis: assess hydration, specific gravity
Monitoring during refeeding
12. Imaging
First-line
- DEXA scan: recommended for females with amenorrhea ≥6 months — osteopenia/osteoporosis develops in ~1 in 3 patients [4-5]
- Chest X-ray: if concern for pericardial effusion or heart failure
When indicated
- Echocardiogram: decreased LV mass, mitral valve prolapse, pericardial effusion [2][6]
- Brain MRI/CT: sulcal widening, ventricular dilatation, cerebral pseudoatrophy (largely reversible with weight restoration) [3-4]
- Abdominal imaging: if concern for superior mesenteric artery syndrome, pancreatitis, or gastric dilatation [6]
When imaging is unnecessary
- Routine brain imaging is not indicated unless focal neurologic deficits or diagnostic uncertainty exist
- Routine echocardiography is not standard unless clinical concern for structural disease
13. Special Tests
Screening tools
Diagnostic scoring
Point-of-care
- Bedside glucose (hypoglycemia risk)
- Urine pregnancy test (amenorrhea workup)
- Urine specific gravity (hydration status)
Bone densitometry
14. ECG
Indications: All patients with suspected AN should have an ECG, especially with significant weight loss, bradycardia, orthostasis, or electrolyte abnormalities. [5-6]
Expected findings
- Sinus bradycardia (most common) [13]
- Low voltage QRS (decreased cardiac muscle mass) [6]
- Right axis deviation [6]
Dangerous patterns to recognize
- QTc prolongation (>440 ms; prevalence ~10% in hospitalized patients) — risk of torsades de pointes and sudden cardiac death [6][9]
- Repolarization abnormalities (T-wave changes, U waves from hypokalemia) [6]
- Arrhythmias (especially in context of electrolyte derangements or QTc-prolonging medications) [9]
15. Assessment
Severity stratification (DSM-5, based on adult BMI): [13]
- Mild: BMI ≥17
- Moderate: BMI 16–16.99
- Severe: BMI 15–15.99
- Extreme: BMI <15
Key clinical pearls
- AN has the highest mortality of any psychiatric disorder — 5–6× age-matched mortality [2]
- Cardiovascular complications account for ~1/3 of deaths [1]
- Normal labs do not exclude serious illness — laboratory results are often normal early in the disease [6]
- Atypical AN (normal/overweight BMI with significant weight loss) can produce the same medical complications [5]
- Two subtypes: restricting and binge-eating/purging — the latter carries additional risks (esophageal tears, metabolic alkalosis, dental erosion, renal injury) [4]
Complications to anticipate
- Refeeding syndrome during nutritional rehabilitation [7]
- End-stage renal disease (5.2% at 21-year follow-up) [4]
- Osteoporosis (may not recover with weight restoration) [5]
- Persistent neurocognitive deficits in some patients [4]
16. Treatment Plan
Initial stabilization (ED/inpatient)
- IV access, cardiac monitoring, orthostatic vitals
- Correct dehydration cautiously (avoid rapid fluid boluses)
- Correct electrolyte abnormalities: K⁺, Mg²⁺, PO₄³⁻ repletion
- Treat hypoglycemia
- Warm blankets for hypothermia
Refeeding protocol
- Thiamine 100 mg IV/PO before initiating any dextrose or feeding [11]
- Start 1,500–2,000 kcal/day with incremental increases [5]
- Monitor electrolytes q12h for first 72 hours in high-risk patients [11]
- Prophylactic electrolyte supplementation (K⁺ 2–4 mmol/kg/day, PO₄³⁻ 0.3–0.6 mmol/kg/day, Mg²⁺ 0.2–0.4 mmol/kg/day) [8]
- Restrict sodium (<1 mmol/kg/day) and fluid (<20 mL/kg/day) in early refeeding [8]
- Target weight gain: 0.9–1.8 kg/week inpatient; 0.5–0.9 kg/week outpatient [5]
The following figure illustrates the pathophysiology of refeeding syndrome — the insulin-mediated intracellular shift of phosphate, potassium, and magnesium that occurs when carbohydrates are reintroduced after starvation:
Medications
- Electrolyte repletion as above
- Multivitamin daily for ≥10 days [11]
- SSRIs for comorbid anxiety/depression (not for weight gain) [10]
- Avoid bupropion (purging behaviors) and QTc-prolonging agents [10]
- APA recommends against parenteral nutrition [5]
Psychotherapy
- Family-based treatment (FBT) is first-line for children and adolescents [4]
- CBT or enhanced CBT for adults [10]
17. Disposition
Admission criteria (per Society for Adolescent Health and Medicine / AAP): [6][16]
- BMI ≤75% median for age/sex (adolescents) or BMI ≤15 (adults) [4]
- Severe bradycardia (HR <50 daytime, <45 nighttime)
- Hypotension <90/45 mmHg
- Hypothermia <96°F (35.6°C)
- Significant orthostatic changes
- ECG abnormalities (prolonged QTc, arrhythmias)
- Electrolyte disturbances (hypokalemia, hyponatremia, hypophosphatemia)
- Acute medical complications (syncope, seizures, cardiac failure, pancreatitis)
- Acute food refusal or uncontrollable binge-purge cycles
- Suicidal ideation or comorbid psychiatric emergency
- Failure of outpatient treatment
Discharge criteria
- Medical stability: stable vital signs, resolving orthostasis
- Electrolytes normalizing and tolerating oral intake
- No active suicidal ideation
- Outpatient multidisciplinary team in place (therapist, dietitian, PCP/psychiatrist)
Observation indications
- Borderline vital sign abnormalities
- Mild electrolyte derangements corrected in ED
- Awaiting psychiatric evaluation
Specialist consultation triggers
- Psychiatry: all patients (comorbid psychiatric illness, suicidality, capacity assessment)
- Cardiology: significant QTc prolongation, arrhythmias, structural cardiac changes
- Nephrology: declining GFR, AKI
- Endocrinology: prolonged amenorrhea, osteoporosis management
- GI: suspected SMA syndrome, pancreatitis, GI bleeding
18. Follow Up / Return Precautions
Follow-up timing
- Weekly medical and laboratory monitoring during active weight restoration [4]
- Weekly therapy sessions (FBT or CBT) [4]
- DEXA scan monitoring for bone density (ongoing if amenorrhea persists) [5]
- Electrolytes and metabolic panel at each visit during early recovery
Return precautions (counsel patient and family)
- Dizziness, fainting, or near-syncope
- Chest pain, palpitations, or irregular heartbeat
- Severe weakness or inability to stand
- Confusion, seizures
- Inability to keep food/fluids down
- Worsening depression or suicidal thoughts
- Peripheral edema, rapid weight gain (refeeding concern)
- Abdominal distension or severe pain
Expected recovery course
- Most effects of starvation (electrolyte, nutritional, cognitive disturbances) improve with weight gain [5]
- Bone density may not fully recover — requires ongoing monitoring and management [5]
- Brain volume changes (pseudoatrophy) are largely reversible with weight restoration, though some neurocognitive patterns may persist [4]
- High relapse rate; ~40% of hospitalized youth require readmission [1]
References
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2. Incidence and Risk of Cardiovascular Outcomes in Patients With Anorexia Nervosa. — Tseng MM, Chiou KR, Shao JY, Liu HY. JAMA Network Open. 2024.
3. Eating Disorders. — Treasure J, Duarte TA, Schmidt U. Lancet. 2020.
4. Anorexia Nervosa. — Mitchell JE, Peterson CB. The New England Journal of Medicine. 2020.
5. Eating Disorders: A Review. — Attia E, Walsh BT. The Journal of the American Medical Association. 2025.
6. Identification and Management of Eating Disorders in Children and Adolescents. — Hornberger LL, Lane MA. Pediatrics. 2021.
7. Malnutrition in Adults. — Cederholm T, Bosaeus I. The New England Journal of Medicine. 2024.
8. Management of Disease-Related Malnutrition for Patients Being Treated in Hospital. — Schuetz P, Seres D, Lobo DN, et al. Lancet. 2021.
9. Cardiovascular Consequences of Anorexia Nervosa: QT Prolongation, Bradycardia, and Structural Cardiac Changes. — Poudel J, Rimal M, Giri A, et al. Southern Medical Journal. 2026.
10. Treating Patients With Eating Disorders: Guidelines From the American Psychiatric Association. — Arnold MJ. American Family Physician. 2024.
11. ASPEN Consensus Recommendations for Refeeding Syndrome. — da Silva JSV, Seres DS, Sabino K, et al. Nutrition in Clinical Practice : Official Publication of the American Society for Parenteral and Enteral Nutrition. 2020.
12. Prophylactic Supplementation of Phosphate, Magnesium, and Potassium for the Prevention of Refeeding Syndrome in Hospitalized Individuals With Anorexia Nervosa. — Gallagher D, Parker A, Samavat H, Zelig R. Nutrition in Clinical Practice : Official Publication of the American Society for Parenteral and Enteral Nutrition. 2022.
13. Diagnostic and Statistical Manual of Mental Disorders. — Dilip V. Jeste, Jeffrey A. Lieberman, David Fassler, et al American Psychiatric Association (2022). 2022.
14. The Intersection Between Eating Disorders and Gastrointestinal Disorders: A Narrative Review and Practical Guide. — Staller K, Abber SR, Burton Murray H. The Lancet. Gastroenterology & Hepatology. 2023.
15. Nutrition Support. — Dong Wook Kim1, David S. Seres2 Yamada's Textbook of Gastroenterology 7e. 2022.
16. ACOG Committee Opinion No. 740: Gynecologic Care for Adolescents and Young Women With Eating Disorders. — Committee on Adolescent Health Care Obstetrics and Gynecology. 2018.