title: Urinary excretion of porphyrins, porphobilinogen and δ-aminolaevulinic acid following an attack of acute intermittent porphyria.
abstract: OBJECTIVE
  The porphyrias are a group of rare, mainly inherited, diseases caused by a deficiency of one of the enzymes of the haem biosynthesis pathway. The biochemical hallmark of an acute attack is an increase in urine porphobilinogen (PBG), together with an increase in urinary excretion of δ-aminolaevulinic acid (ALA) and total urine porphyrins (TUP). In patients with acute intermittent porphyria (AIP) the concentrations of the porphyrin precursors are thought to remain elevated for many years following an acute attack, although this has not been well documented.
  
  
  METHODS
  We measured urine ALA, PBG and TUP excretion in 20 patients with AIP following an attack of acute porphyria over a time period of 3 months to 23 years after their last documented acute attack.
  
  
  RESULTS
  We showed that urinary concentrations of all metabolites remain elevated for many years. The urinary half life of TUP was 5.3 years, ALA 7.7 years and PBG 10.6 years. Even after 20 years, PBG concentrations remained elevated above the normal range.
  
  
  CONCLUSIONS
  Our study highlights the difficulties of using urinary analysis for diagnosing recurrent attacks, and also raises important questions about the pathophysiology of the condition.
authors.affiliation: Department of Clinical Biochemistry, King's College Hospital, , London, UK.
authors.forename: Joanne T
authors.initials: JT
authors.lastname: Marsden
authors.forename: David C
authors.initials: DC
authors.lastname: Rees
mesh_terms: D000622:Aminolevulinic Acid / Q000652:urine*; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D011162:Porphobilinogen / Q000652:urine*; D017118:Porphyria, Acute Intermittent / Q000652:urine*; D011166:Porphyrins / Q000652:urine*; D013995:Time
chemical_list: D011166:Porphyrins; D011162:Porphobilinogen; D000622:Aminolevulinic Acid
keywords: Inherited Pathology; Laboratory Tests; Metabolism