Which electrolyte abnormality is the MOST dangerous and directly life-threatening complication associated with recurrent self-induced vomiting in bulimia nervosa?
- A Hypernatraemia
- B Hypercalcaemia
- C Hypokalaemia causing cardiac arrhythmias ✓
- D Metabolic acidosis
Explanation
Recurrent self-induced vomiting causes loss of gastric HCl, leading to hypochloraemic metabolic alkalosis and hypokalaemia. Severe hypokalaemia (<3.0 mEq/L) is the most immediately life-threatening electrolyte disturbance, predisposing to potentially fatal cardiac arrhythmias including ventricular tachycardia and fibrillation. The combination of hypokalaemia and metabolic alkalosis is characteristic of purging-type eating disorders. Other complications include parotid enlargement, dental erosion (perimylolysis), Mallory-Weiss tears, and Russell's sign (dorsal hand calluses from self-induced vomiting).
Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.
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