Residency · Residency · Psychiatry
Anorexia Nervosa: Medical Complications and Psychiatric Management
Introduction
Anorexia nervosa (AN) has the highest mortality rate of any psychiatric disorder, with death resulting from medical complications and suicide. It is characterized by restriction of energy intake leading to significantly low body weight, intense fear of gaining weight, and disturbance in body image perception. Effective management requires integration of psychiatric care with close medical monitoring and nutritional rehabilitation.
Epidemiology
Lifetime prevalence: approximately 0.5-1% in women, 0.1-0.3% in men. Peak onset: adolescence (ages 14-19) Mortality rate: approximately 5-6% per decade of illness; standardized mortality ratio approximately 5.9. Increasingly recognized in males, older adults, and individuals of all racial and ethnic backgrounds.
DSM-5 Diagnostic Criteria
Restriction of energy intake relative to requirements leading to significantly low body weight (in context of age, sex, developmental trajectory, and physical health) Intense fear of gaining weight or persistent behavior that interferes with weight gain. Disturbance in the way body weight or shape is experienced, undue influence of body weight on self-evaluation, or persistent lack of recognition of the seriousness of current low body weight.
Subtypes
Restricting type: weight loss achieved through dieting, fasting, or excessive exercise. Binge-eating/purging type: recurrent episodes of bingeing or purging (vomiting, laxatives, diuretics)
Medical Complications
| System | Complications | Key Findings/Labs | Reversibility |
|---|---|---|---|
| Cardiovascular | Bradycardia, hypotension, QTc prolongation, cardiac atrophy | HR <60, ECG changes, pericardial effusion | Mostly reversible with weight restoration |
| Metabolic/Electrolyte | Hypokalemia, hypophosphatemia, hypomagnesemia, hypoglycemia | BMP, Mg, Phos; metabolic alkalosis (purging) or acidosis (laxatives) | Reversible with correction |
| Endocrine | Amenorrhea, low estrogen/testosterone, elevated cortisol, low T3 | FSH/LH, estradiol, TSH/T3, cortisol | Reversible with weight restoration |
| Skeletal | Osteopenia/osteoporosis, fractures | DXA scan (after 6 months amenorrhea) | May be irreversible |
| GI | Delayed gastric emptying, constipation, SMA syndrome, parotid enlargement | Serum amylase (salivary); dental erosion | Mostly reversible |
| Neurological | Brain volume loss, peripheral neuropathy, cognitive impairment | MRI (if indicated); neuropsych testing | Partially reversible |
| Hematological | Pancytopenia, bone marrow hypoplasia | CBC | Reversible |
Cardiovascular
Bradycardia (heart rate < 60 bpm), hypotension, orthostatic changes. QTc prolongation (risk of fatal arrhythmia), particularly with electrolyte disturbances. Mitral valve prolapse, pericardial effusion. Cardiac atrophy with reduced cardiac output.
Metabolic and Electrolyte
Hypokalemia (from purging): risk of cardiac arrhythmia and muscle weakness. Hypophosphatemia, hypomagnesemia, hypoglycemia. Metabolic alkalosis (from vomiting) or acidosis (from laxative abuse) Elevated blood urea nitrogen, elevated liver transaminases.
Endocrine
Hypothalamic amenorrhea: cessation of menses due to suppression of GnRH pulsatility. Low estrogen, low testosterone (in males) Elevated cortisol (chronic stress response) Sick euthyroid syndrome (low T3) Growth hormone resistance with elevated GH and low IGF-1.
Skeletal
Osteopenia and osteoporosis: occur early and may be irreversible. Increased fracture risk; DXA scan recommended after 6 months of amenorrhea. Weight restoration is the primary treatment; no effective pharmacotherapy for bone loss in AN.
Gastrointestinal
Delayed gastric emptying, early satiety, bloating, constipation. Superior mesenteric artery syndrome (SMA syndrome) in severe cases. Parotid gland enlargement and dental erosion in purging subtype. Elevated serum amylase (salivary fraction) in purging.
Neurological
Brain volume loss (gray and white matter); partially reversible with weight restoration. Peripheral neuropathy. Cognitive impairment: poor concentration, executive dysfunction.
Refeeding Syndrome
Definition and Risk
Potentially fatal shift in fluids and electrolytes when malnourished patients are refed too rapidly. Hallmark: hypophosphatemia leading to cardiac failure, respiratory failure, delirium, and death. Highest risk in patients with BMI < 15, prolonged starvation, or significant electrolyte abnormalities.
Prevention
Initiate nutrition slowly: "start low, go slow" approach; begin with 1000-1200 kcal/day and increase by 200-300 kcal every 2-3 days. Monitor electrolytes (phosphorus, potassium, magnesium) daily during the first 1-2 weeks. Supplement thiamine before refeeding to prevent Wernicke encephalopathy. Supplement phosphorus prophylactically in high-risk patients. Monitor for edema, tachycardia, and respiratory distress.
Psychiatric Management
Psychotherapy
Family-based treatment (FBT / Maudsley approach): first-line for adolescents; parents take charge of refeeding. CBT-Enhanced (CBT-E): first-line for adults; addresses overvaluation of shape and weight. Specialist Supportive Clinical Management (SSCM): combines clinical management with supportive psychotherapy. Motivational enhancement techniques to address ambivalence about recovery.
Pharmacotherapy
No medication has demonstrated efficacy for the core symptoms of AN (weight restoration, body image disturbance) SSRIs are not effective for weight gain in underweight AN patients; may have a role in relapse prevention after weight restoration. Olanzapine (low dose, 2.5-10 mg): modest evidence for weight gain and anxiety reduction; monitor metabolic effects. Treat comorbid conditions (depression, anxiety, OCD) after nutritional stabilization, as many symptoms improve with weight restoration.
Levels of Care
Outpatient: medically stable, BMI typically > 17, motivated, adequate psychosocial support. Intensive outpatient / partial hospitalization: insufficient progress with outpatient treatment. Residential treatment: persistent symptoms, failed less intensive treatment. Medical hospitalization: hemodynamic instability, severe electrolyte abnormalities, BMI < 15, acute suicidality, refeeding monitoring.
Criteria for Medical Hospitalization (APA Guidelines)
Heart rate < 50 bpm, blood pressure < 80/60 mmHg. Orthostatic pulse increase > 20 bpm or BP drop > 20 mmHg systolic. Temperature < 36 C, glucose < 60 mg/dL. Significant electrolyte disturbances. Rapid or uncontrolled weight loss.
Key Clinical Pearls
Medical stabilization takes priority over psychiatric treatment; a starving brain cannot benefit from psychotherapy. Refeeding syndrome is preventable with careful nutritional management; monitor phosphorus closely. Bradycardia in AN is not benign athletic bradycardia; it reflects cardiac muscle wasting. FBT is superior to individual therapy for adolescents with AN; empower parents as agents of change. Recovery is possible but often takes years; approximately 50% of patients achieve full recovery.
References
- American Psychiatric Association. Practice guideline for the treatment of patients with eating disorders. 3rd ed. Am J Psychiatry. 2006;163(7 Suppl):4-54.
- Lock J, Le Grange D. Treatment of anorexia nervosa in adolescents: a randomized controlled trial. Arch Gen Psychiatry. 2010;67(10):1025-1032.
- Mehler PS, Brown C. Anorexia nervosa: medical complications. J Eat Disord. 2015;3:11.
- Attia E, Steinglass JE, Walsh BT, et al. Olanzapine versus placebo in adult outpatients with anorexia nervosa: a randomized clinical trial. Am J Psychiatry. 2019;176(6):449-456.