title: Best practice guidelines on first-line laboratory testing for porphyria.
abstract: The porphyrias are disorders of haem biosynthesis which present with acute neurovisceral attacks or disorders of sun-exposed skin. Acute attacks occur mainly in adults and comprise severe abdominal pain, nausea, vomiting, autonomic disturbance, central nervous system involvement and peripheral motor neuropathy. Cutaneous porphyrias can be acute or chronic presenting at various ages. Timely diagnosis depends on clinical suspicion leading to referral of appropriate samples for screening by reliable biochemical methods. All samples should be protected from light. Investigation for an acute attack: • Porphobilinogen (PBG) quantitation in a random urine sample collected during symptoms. Urine concentration must be assessed by measuring creatinine, and a repeat requested if urine creatinine <2 mmol/L. • Urgent porphobilinogen testing should be available within 24 h of sample receipt at the local laboratory. Urine porphyrin excretion (TUP) should subsequently be measured on this urine. • Urine porphobilinogen should be measured using a validated quantitative ion-exchange resin-based method or LC-MS. • Increased urine porphobilinogen excretion requires confirmatory testing and clinical advice from the National Acute Porphyria Service. • Identification of individual acute porphyrias requires analysis of urine, plasma and faecal porphyrins. Investigation for cutaneous porphyria: • An EDTA blood sample for plasma porphyrin fluorescence emission spectroscopy and random urine sample for TUP. • Whole blood for porphyrin analysis is essential to identify protoporphyria. • Faeces need only be collected, if first-line tests are positive or if clinical symptoms persist. Investigation for latent porphyria or family history: • Contact a specialist porphyria laboratory for advice. Clinical, family details are usually required.
authors.affiliation: 1 Department of Medical Biochemistry and Immunology, University Hospital of Wales, Cardiff, UK.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Woolf
authors.affiliation: 2 Reference Biochemistry Laboratories, Viapath, King's College Hospital, London, UK.
authors.forename: Joanne T
authors.initials: JT
authors.lastname: Marsden
authors.affiliation: 3 Department of Clinical Biochemistry, Leeds Teaching Hospitals Trust, Leeds, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Degg
authors.affiliation: 1 Department of Medical Biochemistry and Immunology, University Hospital of Wales, Cardiff, UK.
authors.forename: Sharon
authors.initials: S
authors.lastname: Whatley
authors.affiliation: 4 Department of Clinical Biochemistry, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Reed
authors.affiliation: 5 Department of Biochemistry, St James Hospital, Dublin, Ireland.
authors.forename: Nadia
authors.initials: N
authors.lastname: Brazil
authors.affiliation: 4 Department of Clinical Biochemistry, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: M Felicity
authors.initials: MF
authors.lastname: Stewart
authors.affiliation: 1 Department of Medical Biochemistry and Immunology, University Hospital of Wales, Cardiff, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Badminton
mesh_terms: D000208:Acute Disease; D000465:Algorithms; D002853:Chromatography, Liquid; D002908:Chronic Disease; D003124:Colorimetry; D005243:Feces / Q000737:chemistry; D005470:Fluorometry; D006801:Humans; D013058:Mass Spectrometry; D011162:Porphobilinogen / Q000652:urine*; D011164:Porphyrias / Q000097:blood / Q000145:classification / Q000175:diagnosis* / Q000652:urine; D011166:Porphyrins / Q000097:blood / Q000652:urine; D011786:Quality Control; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors
chemical_list: D011166:Porphyrins; D011162:Porphobilinogen
keywords: Inborn errors of metabolism; clinical studies; colourimetry; fluorometry; laboratory methods