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Anorexia Nervosa

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Anorexia Nervosa

Key Points

  • Anorexia nervosa involves severe dietary restriction, distorted weight perception, and high medical risk.
  • Starvation and suicide are major causes of mortality in anorexia.
  • In epidemiologic comparisons, mortality risk is markedly elevated in youth with anorexia, and delayed recognition in males is a persistent safety concern.
  • Refeeding must be gradual to reduce risk of life-threatening refeeding syndrome.
  • Nursing care prioritizes medical stabilization, suicide screening, and therapeutic alliance.

Pathophysiology

Anorexia nervosa reflects persistent energy restriction with neurobehavioral reinforcement of fear-driven eating avoidance. Starvation causes multisystem dysfunction including cardiovascular instability, endocrine disruption, renal risk, and electrolyte abnormalities.

Psychological rigidity and perfectionism sustain restrictive behaviors despite physical decline. Malnutrition further worsens cognition and mood, creating a self-perpetuating cycle.

Body-image disturbance can include cognition-level errors (for example thought-shape-fusion patterns), where food-related thoughts are misinterpreted as evidence of immediate body-shape or weight change.

Current evidence summaries in med-surg pathways also describe anorexia-related dopaminergic/serotonergic dysregulation and endocrine disruption (for example thyroid suppression, stress-related cortisol elevation, and reduced gonadal hormones), which can worsen mood, fatigue, and reproductive dysfunction.

Classification

  • Restricting pattern: Severe caloric restriction without regular binge-purge behavior.
  • Binge/purge pattern: Restriction plus episodic purging or compensatory behavior.
  • BMI severity specifier: Mild (BMI >17), moderate (16.0-16.99), severe (15.0-15.99), extreme (<15) plus overall medical/psychiatric compromise.
  • Weight-status screening context: In adults, severe restriction often presents with BMI below 18.5; in children/adolescents, growth-chart context (for example low percentile trends such as below the 5th percentile) is more appropriate than adult cutoffs.
  • Sex/age risk context: Males represent a substantial minority of anorexia cases (about one-quarter in some datasets) and may have later diagnosis with worse outcomes; adolescents and young adults carry high mortality burden.
  • Common prevalence context: Clinical prevalence is often reported around 0.5-1% in AFAB populations and lower but clinically significant in AMAB populations; under-recognition in AMAB clients can delay diagnosis.

Nursing Assessment

NCLEX Focus

Prioritize immediate medical instability and suicide risk before long-term behavior work.

  • Assess nutritional status, weight trajectory, vitals, orthostatic changes, and hydration.
  • Assess electrolyte and metabolic abnormalities, arrhythmia risk, and organ compromise.
  • Assess med-surg instability labs commonly used in acute evaluation (for example CBC, comprehensive metabolic panel, thyroid-stimulating hormone, 25-hydroxyvitamin D, and testosterone in male patients).
  • Use validated anorexia-focused screening tools when available (for example SCOFF or EDDS) to support early detection and symptom tracking.
  • Assess distorted body image, perfectionism, and restrictive rituals.
  • Assess impaired illness insight (under-recognition of seriousness despite low weight) and persistent fear of weight gain.
  • Assess depression, anxiety, obsessive features, and suicidal ideation.
  • In AMAB clients, assess sex-hormone suppression effects (for example reduced libido or testosterone-related symptoms) that may accompany severe malnutrition.
  • Assess trauma burden and PTSD comorbidity because trauma exposure is common and can worsen treatment complexity.
  • Use structured screening tools for eating-disorder severity and safety risk when available.
  • Assess chronic starvation findings such as lanugo, cold intolerance, bradycardia/hypotension, constipation, brittle hair/nails, menstrual disruption, osteopenia/osteoporosis, and progressive multisystem injury.
  • Monitor objective inpatient cues (rapid post-meal bathroom use, food hiding/stashing, concealed eating, excessive activity) and document behavior frequency trends.
  • Use BMI trends with caution: very low or rapidly falling BMI indicates urgent medical risk, but BMI should be interpreted with body composition and other clinical indicators.
  • Recognize BMI limitations in high-muscle athletes and across diverse body-composition distributions; combine BMI with additional measures (for example waist/visceral adiposity trends) and full clinical context.
  • When nutrition teams use ideal-body-weight targets for risk stratification, treat them as one assessment input rather than a stand-alone determination of severity.
  • In female patients of reproductive age, include beta-hCG and targeted drug-screen review in the initial workup when clinically indicated.
  • Escalate for cardiopulmonary diagnostic support (for example echocardiogram in dyspnea/syncope/murmur presentations) and consider provider-directed abdominal imaging in prolonged amenorrhea or concerning GI symptoms.

Nursing Interventions

  • Implement medically supervised nutrition restoration with close monitoring.
  • Monitor for refeeding syndrome and escalate care for arrhythmia or delirium signs.
  • During early refeeding, target gradual scheduled gain and notify the provider for rapid fluid-shift patterns (for example gain greater than about 5 lb in 1 week with edema or respiratory change).
  • Maintain structured meal support and milieu consistency.
  • Maintain a therapeutic and safe care environment (unit and community transitions), including suicide-risk precautions and close observation when self-harm risk is high.
  • During weight/BMI monitoring, assess whether seeing numeric values is triggering and individualize disclosure approach.
  • Consider blind weighing during acute high-anxiety stages and transition toward open weighing as recovery readiness improves.
  • Monitor intake/output, bowel patterns, and post-meal activity; supervise after meals in inpatient/residential settings to reduce compensatory behaviors.
  • In medically unstable inpatient pathways, implement facility suicide precautions and supervised feeding per protocol.
  • Prevent pressure injuries in severe malnutrition and monitor for rhythm changes, hypotension, and electrolyte instability.
  • Provide suicide precautions and crisis resources when indicated.
  • Use structured suicide-screening tools as indicated (for example BSI) and provide crisis-access escalation teaching (for example 988/911 in U.S. workflows).
  • Coordinate psychotherapy, dietitian care, and family involvement.
  • Include evidence-based psychotherapy options such as SSCM, MANTRA, CBT, and family-based treatment (first-line in many child/adolescent pathways) based on age and setting.
  • Escalate to inpatient stabilization when severe electrolyte imbalance, arrhythmia/hypotension/hypothermia, weight below approximately 75% of healthy body weight, or active suicide risk is present.
  • For adolescents, support family-based therapy models where caregivers are coached to structure refeeding and meal restoration at home.
  • In severe malnutrition, prepare for hospitalization-level nutritional rehabilitation (tube feeding or TPN) with close electrolyte surveillance.
  • Use team-based delegation appropriately (for example assistive personnel may collect weights/vitals under RN supervision), while the RN retains responsibility for interpretation, medication safety, and care-plan decisions.

Refeeding Syndrome Risk

Rapid nutritional repletion can trigger dangerous fluid and electrolyte shifts, including fatal arrhythmias.

Pharmacology

No FDA-approved medication specifically treats anorexia nervosa. Pharmacotherapy is symptom-targeted for comorbid depression, anxiety, obsessive symptoms, or sleep disturbance.

In selected cases, prescribers may use off-label atypical antipsychotic strategies (for example olanzapine) to support weight restoration and reduce severe eating-related anxiety.

Selected clients may receive SSRIs (for example fluoxetine) for comorbid anxiety/depression burden after nutritional stabilization, plus symptom-targeted support such as potassium replacement for hypokalemia, constipation management, or bone-health support in prolonged malnutrition contexts.

Nurses monitor medication response within the context of malnutrition, altered metabolism, and cardiac vulnerability.

Clinical Judgment Application

Clinical Scenario

A client with severe restriction presents with low weight, orthostatic tachycardia, anxiety, and rigid food refusal.

  • Recognize Cues: Marked malnutrition and physiologic instability with persistent cognitive distortion.
  • Analyze Cues: High risk for acute medical decompensation and self-harm.
  • Prioritize Hypotheses: Stabilization and safety are immediate priorities.
  • Generate Solutions: Begin monitored refeeding, electrolyte surveillance, and suicide screening.
  • Take Action: Implement multidisciplinary treatment with structured nutritional and psychiatric care.
  • Evaluate Outcomes: Confirm physiologic stabilization and gradual treatment engagement.

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