Harvey's Garden

Anorexia nervosa

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2 min read

Epidemiology

Etiology

Pathophysiology

Clinical features

  • Most patients present with a low BMI.

Associated features of severe malnutrition

  • CNS
    • Hypothermia
      • This is thought to be caused by a disorder of the hypothalamic thermoregulatory centers.
    • Cortical atrophy with associated problems with concentration and reasoning
    • Seizures
      • As a result of dehydration and electrolyte imbalances
    • Depressed mood, fatigue, and poor concentration
  • Cardiac
  • Endocrine
  • GI: Constipation, gastroparesis. t
  • Musculoskeletal
  • Skin and hair

Diagnostics

Tip

Consider screening the following individuals at increased risk:

  • Preteens and adolescents
    • At annual adolescent health visits
    • Evaluation of weight loss
  • Athletes (at annual preparticipation screens)
  • Sexual minority, transgender, and gender diverse youth
  • Patients with a:
    • History of sexual abuse, childhood adversity, or trauma (including bullying)
    • Chronic disease requiring dietary management
    • Psychiatric disorder and those undergoing an initial psychiatric evaluation

Differential diagnostics

Treatment

  • Inpatient Hospitalization Criteria (Urgent Medical Stabilization):
    • Hemodynamic instability: HR < 40 bpm, BP < 90/60 mmHg, symptomatic orthostasis (ΔHR > 20 bpm, ΔSBP > 20 mmHg).
    • Cardiac complications: QTc > 460 ms, marked dysrhythmias, pericardial effusion.
    • Severe electrolyte abnormalities: K⁺ < 3.0 mEq/L, PO₄³⁻ < 2.0 mg/dL, severe hypoglycemia (< 60 mg/dL).
    • Extreme low weight: BMI < 15 kg/m² (< 70% of ideal body weight).
    • Marked dehydration, acute medical complication (e.g., pancreatitis, hepatic failure), or acute suicidality.
  • First-line Treatment:
    • Nutritional Rehabilitation: Supervised caloric intake with structured meal plans (gradual caloric increase to prevent refeeding syndrome).
    • Psychotherapy:
      • Family-Based Therapy (FBT / Maudsley approach): First-line for children and adolescents.
      • Cognitive Behavioral Therapy (CBT): First-line for adults.
  • Second-line / Pharmacotherapy:
    • Olanzapine (Atypical Antipsychotic): Indicated if pt fails first-line psychotherapy/nutritional therapy, has severe obsessive food preoccupation, or marked anxiety.
    • Note on Antidepressants: SSRIs/SNRIs are ineffective at low body weight and do not promote weight restoration.
  • Strict Contraindication:
    • Bupropion: Absolutely contraindicated in eating disorders due to significantly lowered seizure threshold.

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