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

Abstract

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 (>or= 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.

Variegate Porphyria

“…155 A greater appreciation of the acute porphyrias, improvements in predictive testing, and changes in prescribing habits have led to a decrease in the incidence of the acute attack. Consequently, many acute attacks occur in patients not known to have porphyria and patients may be diagnosed following admission to an intensive care unit or medical ward with an unexplained neuropathy, 184,195,201 often initially diagnosed as Guillain-Barré syndrome. 182,192,202 There is still uncertainty as to the pathogenesis of the acute attack.…”

Clinical Reasoning: A 20-year-old woman with rapidly progressive weakness

“…4 Seizures are also possible. 5 HCP and VP manifestations may also include photosensitive dermatologic lesions, which are not present in ADP and AIP. Discoloration of urine on exposure to light is common and is due to increased urinary porphyrins.…”

“…5 Clinical clues to the presence of acute porphyria include the distribution of the weakness (with predilection of proximal arm muscles initially, rather than ascending weakness as in GBS), the history of recurrent attacks, and the presence of associated psychiatric symptoms and discolored urine. CSF examination can be normal or demonstrate elevated protein without pleocytosis.…”

Unusual Peripheral Neuropathies. Part III: Intrinsic Inherited Causes

“…13 In one study, porphyrin metabolites were screened for in 108 hospital patients admitted with ''acute polyneuropathy or encephalopathy associated with pain and/or dysautonomia'' and increased urinary porphyrins were detected in 21% of cases. 15 A new diagnosis of primary porphyria was made in 11%, whereas the other 10% had a secondary cause of porphyrinuria.…”