A Woman with Abdominal Pain

Examination showed diffuse tenderness without guarding or rebound, and initial laboratory testing was largely unrevealing except for mild hyponatremia. Despite treatment for presumed viral gastroenteritis, her pain persisted, and she developed confusion, seizures, and severe hyponatremia (serum sodium, 116 mEq/l). Hypertension and tachycardia also developed, and subsequently her urine was observed to darken after exposure to light (Figure 1). Her astute physicians tested her urine for porphyrin precursors, arriving at a diagnosis of acute intermittent porphyria (AIP), a rare cause of abdominal pain that affects mainly women of reproductive age.