Abstract | BACKGROUND: CONTENT: In studying more than 180 patients with EPP and XLP, the Porphyrias Consortium found that erythrocyte protoporphyrin concentrations for some patients were much higher (4.3- to 46.7-fold) than indicated by previous reports provided by these patients. The discrepant earlier reports, which sometimes caused the diagnosis to be missed initially, were from laboratories that measure protoporphyrin only by hematofluorometry, which is intended primarily to screen for lead poisoning. However, the instrument can calculate results on the basis of assumed hematocrits and reports results as "free" and " zinc" protoporphyrin (with different reference intervals), implying separate measurements of metal-free and zinc protoporphyrin. Such misleading reports impair diagnosis and monitoring of patients with protoporphyria. SUMMARY: We suggest that laboratories should prioritize testing for EPP and XLP, because accurate measurement of erythrocyte total and metal-free protoporphyrin is essential for diagnosis and monitoring of these conditions, but less important for other disorders. Terms and abbreviations used in reporting erythrocyte protoporphyrin results should be accurately defined.
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Authors | Eric W Gou, Manisha Balwani, D Montgomery Bissell, Joseph R Bloomer, Herbert L Bonkovsky, Robert J Desnick, Hetanshi Naik, John D Phillips, Ashwani K Singal, Bruce Wang, Sioban Keel, Karl E Anderson |
Journal | Clinical chemistry
(Clin Chem)
Vol. 61
Issue 12
Pg. 1453-6
(Dec 2015)
ISSN: 1530-8561 [Electronic] England |
PMID | 26482161
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Copyright | © 2015 American Association for Clinical Chemistry. |
Chemical References |
- Protoporphyrins
- Reagent Kits, Diagnostic
- zinc protoporphyrin
- protoporphyrin IX
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Topics |
- Adolescent
- Adult
- Child
- Child, Preschool
- Diagnosis, Differential
- Erythrocytes
(chemistry)
- Female
- Fluorometry
(methods)
- Humans
- Infant
- Infant, Newborn
- Lead Poisoning
(blood, diagnosis)
- Male
- Porphyrias
(blood, diagnosis)
- Protoporphyria, Erythropoietic
(blood, diagnosis)
- Protoporphyrins
(blood)
- Reagent Kits, Diagnostic
(standards)
- Reference Values
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