International air travel: a risk factor for attacks in acute intermittent porphyria.

Five patients are reported with acute intermittent porphyria in whom attacks were apparently precipitated by international air travel. In four subjects this was the initial presenting attack and in a fifth the cause of an acute relapse in a patient requiring regular haem arginate prophylaxis. Multifactorial precipitants implicated include, dehydration, missed meals, alcohol use, infection, chronic hypoxia, premenstrual syndrome and stress. Acute intermittent porphyria should be suspected in individuals presenting with unexplained acute abdominal pain following international air travel. Appropriate precautions may reduce the incidence of attacks in known porphyrics.