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The porphyrias [corrected]: characteristics and laboratory tests
1Mayo Clinic, Rochester, Minnesota 55905, USA.
Regulatory Toxicology and Pharmacology : RTP
|August 1, 1996
Summary
Porphyria encompasses seven diseases affecting the nervous system and skin due to heme synthesis disruptions. Diagnostic tests measure heme precursors and by-products, crucial for identifying these conditions, especially after chemical exposure.
Area of Science:
- Biochemistry
- Genetics
- Toxicology
Background:
- Porphyria comprises seven distinct diseases stemming from the heme biosynthesis pathway.
- These conditions manifest as neuropathic and/or dermopathic symptoms due to the accumulation of heme precursors and porphyrins.
Purpose of the Study:
- To provide an overview of porphyria, its underlying mechanisms, clinical manifestations, and diagnostic approaches.
- To highlight the relevance of porphyria testing in cases of toxic chemical exposure.
Main Methods:
- Review of the biochemical disturbances in the heme-forming system.
- Description of clinical presentations, ranging from mild to severe neurological and dermatological symptoms.
- Outline of diagnostic laboratory tests, including the quantitation of delta-aminolevulinic acid (delta ALA), porphobilinogen, and porphyrins, and enzyme activity analysis.
Main Results:
- Accumulation of delta ALA correlates with neurological symptoms.
- Accumulation of photoreactive porphyrins leads to cutaneous photosensitivity.
- Acute episodes can result in paralysis and respiratory failure.
Conclusions:
- Porphyria is a group of disorders characterized by specific biochemical abnormalities.
- Accurate laboratory testing is essential for diagnosis.
- Both inherited and acquired forms of porphyria can be triggered by toxic chemicals, necessitating inclusion in exposure assessments.