Respiratory insufficiency associated with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is a disease that may present with gastrointestinal, psychiatric, or neurologic symptoms. We describe two patients in whom AIP was first diagnosed during episodes of acute respiratory insufficiency. The biochemical defects, clinical presentations, pathophysiology, diagnostic criteria, and treatment of AIP are reviewed. We emphasize that AIP should be considered in the differential diagnosis of every patient with unexplained respiratory failure. Once considered, AIP is relatively simple to diagnose and specific therapeutic measures can be instituted.