Identifying acute porphyria in patients with acute polyneuropathy or encephalopathy.

Neurological complications are important components of an acute attack of porphyria, and early diagnosis and treatment of porphyria could prevent the development of these complications. Pischik et al. investigated the frequency of acute porphyria among patients admitted to neurological wards in Russia. The investigators identified 108 patients with acute polyneuropathy or encephalopathy, along with abdominal pain, back pain and/or dysautonomia. Urine samples were screened for acute porphyria by use of the qualitative Watson-Schwartz test for porphobilinogen and through measurement of coproporphyrin. Twelve patients had acute intermittent porphyria, and 11 had false-positive results. The specificity of the screen would have been improved by omission of the coproporphyrin test. The Watson-Schwartz test is, by itself, unreliable, and any positive test should be confirmed quantitatively. Improved identification of acute porphyria requires heightened clinical awareness and access to urinary porphobilinogen measurement. We suggest that all hospitals that admit acutely ill patients should be able to provide a validated determination of porphobilinogen within 24 h.