Major Medical Consequences of Anorexia Nervosa
Anorexia nervosa causes life-threatening medical complications affecting virtually every organ system, with cardiac complications being the leading cause of death, accounting for at least one-third of all mortality in this disorder. 1, 2
Mortality and Overall Severity
- Anorexia nervosa has the highest mortality rate of any psychiatric disorder, with reported rates around 6%, though estimates range from 5-20% 1, 3, 4, 5
- Up to one-third of deaths are due to cardiac causes, including sudden cardiac death during both starvation and refeeding phases 1, 2
- The risk of death is approximately 12 times higher than age-matched individuals in the general population 6
Cardiovascular Complications
The cardiovascular system is critically affected and represents the most dangerous complication:
- Bradycardia (heart rate <50 beats/minute during the day) is a common and serious finding 2
- Hypotension (<90/45 mm Hg) develops as a physiologic adaptation to malnutrition 1, 2
- QTc interval prolongation occurs frequently, particularly with rapid weight loss, low body mass index, and concurrent electrolyte disturbances, predisposing to life-threatening ventricular arrhythmias 1
- Cardiac muscle atrophy and pericardial effusions develop with prolonged starvation 1
- Orthostatic changes (pulse increase >20 beats/min or blood pressure drop >20 mm Hg systolic on standing) indicate cardiovascular instability 2
Metabolic and Thermoregulatory Complications
- Hypothermia (body temperature <96°F) results from loss of thermoregulatory capacity 1, 2
- Electrolyte disturbances are common, particularly in patients who engage in purging behaviors, and can trigger cardiac arrhythmias 1
Gastrointestinal Complications
- Delayed gastric emptying, especially of solids, is well-documented 1
- Delayed small and large bowel transit occurs as a consequence of malnutrition 1
- Mega-duodenum and absence of propagating migrating motor complexes (MMCs) have been reported, though these can improve with nutritional rehabilitation 1
- Superior mesenteric artery syndrome (Wilkie's syndrome) can develop with sudden weight loss, causing compression of the third part of the duodenum 1
Nutritional and Systemic Effects
- Malnutrition itself impairs gut function, causing mucosal atrophy, reduced gastric acid and pancreatic enzyme secretion, and increased bacterial colonization of the upper gut 1
- Poor growth and delayed sexual development occur when food restriction is prolonged, particularly in adolescents 1
- Every body system may be adversely affected by the progressive malnutrition 3, 7
Refeeding Syndrome
A critical and potentially fatal complication occurs during nutritional rehabilitation:
- The refeeding syndrome is characterized by cardiac, neurological, and hematological complications triggered by fluid and electrolyte disturbances during refeeding of chronically starved individuals 1
- Cardiac complications typically occur within the first week of refeeding, particularly in patients with severe malnutrition (<70% ideal body weight) 1
- Hypophosphatemia is a key feature and predictor of refeeding complications 1
- Total parenteral nutrition carries particularly high risk for refeeding syndrome 1
Critical Clinical Pitfall
More than half of adolescents with eating disorders have normal laboratory results despite being medically unstable 2. This means:
- Normal laboratory values do not indicate medical safety 2
- Clinical assessment of vital signs (heart rate, blood pressure, temperature, orthostatic changes) is more reliable than laboratory testing for detecting medical instability 2
- Waiting for laboratory abnormalities before taking action can be dangerous 2
Reversibility
Remarkably, most medical complications of anorexia nervosa are treatable and reversible with optimal medical care and nutritional rehabilitation 1, 3. However, some complications can have permanent adverse effects if not diagnosed and addressed early in the disease course 7.