Acute intermittent porphyria: psychosis as the only clinical manifestation.

Acute intermittent porphyria (AIP) is the most common of the four forms of neuroporphyria. AIP mimics a variety of disorders and thus poses a diagnostic quagmire. Abdominal pain occurs in 90-95% of the attacks. Some patients develop psychiatric symptoms such as psychosis similar to schizophrenia. The diagnostic difficulty may lead to under-diagnosis of patients who present with strictly psychiatric symptoms. This assumption is supported by a high prevalence of AIP in psychiatric hospitals. Therefore, we encourage a high index of suspicion for AIP in psychiatric patients in order to prevent false psychiatric diagnosis. In addition we discuss psychotropic drugs that may exacerbate acute attacks in undiagnosed patients. We report a case in which the diagnosis of AIP was clouded by the presence of only psychiatric symptoms. The clue for diagnosis was an anamnestic detail of the use of a porphyrogenic drug prior to the admission. The diagnosis of AIP was supported by excess of alpha aminolevulinic acid (ALA) and porphobilinogen (PBG) in urine concomitantly with a decrease in porphobilinogen deaminase (PBGD) activity in erythrocytes. The diagnosis was further strengthened by the fact that the patient's father was identified as an AIP carrier. However, in the absence of typical organic symptoms of porphyria, one cannot definitely rule out the presence of schizophrenia in this patient in addition to AIR