[Acute intermittent porphyria: a diagnostic dilemma].

Acute intermittent porphyria (AIP) is a rare condition characterized by abdominal pain and a wide range of nonspecific symptoms. We report the case of a 24-year-old woman with syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and motor and sensory neurological deficits due to an attack of acute porphyria. The patient presented to the emergency department with abdominal pain. The results of physical examination and laboratory investigations were normal. Two days after admission, the patient developed seizures as a result of hyponatremia due to SIADH, which, together with the observation of red urine, led to the diagnosis of AIP. Before hematin was available, the patient developed autonomic instability and peripheral neuropathy with muscular weakness. We briefly review the clinical and laboratory features of this syndrome and emphasize the importance of its inclusion in the differential diagnosis of gastrointestinal diseases, hyponatremia and neuropathy. Prompt recognition of this entity and early specific treatment with haem arginate are important to prevent irreversible complications. Copyright 2009 Elsevier España, S.L. All rights reserved.