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The porphyrias, appropriate test selection
1Division of Biochemistry, The Ottawa Hospital, and Department of Pathology and Laboratory Medicine, The University of Ottawa, Canada. jhindmarsh@ottawahospital.on.ca
Background:
Clinical and biochemical diagnosis of the porphyrias is a difficult task and is currently based upon review of the clinical features and measurement of the various porphyrin metabolites in body fluids.
Materials:
Different techniques are available for the diagnosis of the porphyrias and the identification of the eventual defect(s), ranging from simple biochemical measurement of aminolevulinic acid (ALA) and porphobilinogen (PBG) through enzymatic assays to the investigation of genetic abnormalities.
Results:
Except for erythrocyte porphobilinogen deaminase, the use of porphyrin enzyme measurement is beyond the scope of most laboratories. Genetic studies are progressing apace in all the porphyrias and are rapidly becoming the 'gold standard' for difficult diagnoses, but actually, these techniques are confined to highly specialized research laboratories.
Conclusion:
At present time, most clinical chemists must rely on the measurement of porphyrin metabolites for diagnosis and a proposed algorithm for this purpose is presented.