Is screening for urinary porphobilinogen useful among patients with acute polyneuropathy or encephalopathy?

Acute porphyrias are a group of inherited metabolic disorders representing overproduction syndromes with the formation of neurotoxic haem precursors. Clinical manifestations consist of acute attacks, which include abdominal pain, dysautonomia, mental symptoms, polyneuropathy and seizures mimicking many other acute neurological disorders. Porphyrin metabolites were screened in 108 patients with acute polyneuropathy or encephalopathy associated with pain and/or dysautonomia, who attended neurological wards, in order to evaluate the number of patients with acute porphyria. Urinary porphyrins and their precursors were increased in 21 % of the cases. Surprisingly many patients (11 %) had previously undiagnosed acute porphyria. Half of these patients had had mild to moderate symptoms of acute porphyria previously. Secondary porphyrinuria, which was mainly transient coproporphyrinuria because of hepatopathy, was also common (10 %). Of the 108 patients studied, the levels of urinary porphyrins or their precursors were normal in the majority (79 %) of the cases, who commonly had Guillain-Barré syndrome (40 %). Epileptic seizures were also frequent (18 %), but none of the patients with acute porphyria had solely epileptic seizures without prolonged confusion (≥ 1 day). Based on our findings, acute inherited porphyria is not infrequent among the selected group of neurological patients and screening of urinary PBG is cost-beneficial. Since the correct diagnosis of a hereditary disease is essential, genetic screening should be performed whenever possible for patients with clinically and biochemically confirmed acute porphyria.