Evaluating patients with possible diagnoses of erythropoietic protoporphyria or X-linked dominant protoporphyria
Establishing a biochemical diagnosis of erythropoietic protoporphyria and X-linked dominant protoporphyria
This test should not be ordered in conjunction with PEE / Porphyrins Evaluation, Whole Blood.
The following information is available:
-Porphyria (Acute) Testing Algorithm
High-Performance Liquid Chromatography (HPLC) with Fluorescence Detection
EPP (Erythropoietic Protoporphyria)
Erythropoietic Protoporphyria
Free Protoporphyrin
Zinc Protoporphyrin
X-linked Dominant Protoporphyria (XLDPP or XDP)
This test should not be ordered in conjunction with PEE / Porphyrins Evaluation, Whole Blood.
The following information is available:
-Porphyria (Acute) Testing Algorithm
Whole blood
This test is for assessment for protoporphyria. The preferred test for lead toxicity in children is blood lead. For more information see PBDV / Lead, Venous with Demographics, Blood or PBDC / Lead, Capillary, with Demographics, Blood. The preferred screening test for suspicion of a hepatic porphyria is urine porphyrins. For more information see PQNRU / Porphyrins, Quantitative, Random, Urine. This test should not be ordered with PEE / Porphyrins Evaluation, Whole Blood
Include a list of medications the patient is currently taking.
All porphyrin tests on whole blood can be performed on 1 tube.
Patient Preparation: Patient must not consume any alcohol for 24 hours before specimen collection.
Container/Tube:
Preferred: Green top (sodium heparin)
Acceptable: Dark blue top (metal free heparin), green top (lithium heparin), or lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions: Refrigerate specimen as soon as possible.
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
3 mL
Gross hemolysis | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Whole blood | Refrigerated | 7 days |
Evaluating patients with possible diagnoses of erythropoietic protoporphyria or X-linked dominant protoporphyria
Establishing a biochemical diagnosis of erythropoietic protoporphyria and X-linked dominant protoporphyria
This test should not be ordered in conjunction with PEE / Porphyrins Evaluation, Whole Blood.
The following information is available:
-Porphyria (Acute) Testing Algorithm
The porphyrias are a group of inherited disorders resulting from enzyme defects in the heme biosynthetic pathway. Depending on the specific enzyme involved, various porphyrins and their precursors accumulate in different specimen types. The patterns of porphyrin accumulation in erythrocytes and plasma and excretion of the heme precursors in urine and feces allow for the detection and differentiation of the porphyrias.
Testing protoporphyrin fractions is most informative for patients with a clinical suspicion of erythropoietic protoporphyria (EPP) or X-linked dominant protoporphyria (XLDPP). Clinical presentation of EPP and XLDPP is identical with onset of symptoms typically occurring in childhood. Cutaneous photosensitivity in sun-exposed areas of the skin generally worsens in the spring and summer months. Common symptoms may include itching, edema, erythema, stinging or burning sensations, and occasionally scarring of the skin in sun-exposed areas. Although genetic in nature, environmental factors exacerbate symptoms, significantly impacting the severity and course of disease.
Erythropoietic protoporphyria is caused by diminished ferrochelatase resulting in significantly increased free protoporphyrin levels in erythrocytes, plasma, and feces.
X-linked dominant protoporphyria is caused by gain-of-function variants in the C-terminal end of ALAS2 gene and results in elevated erythrocyte levels of free and zinc-complexed protoporphyrin in erythrocytes, and total protoporphyrin levels in plasma and feces.
Other possible causes of elevated erythrocyte zinc-complexed protoporphyrin may include:
-Iron-deficiency anemia, the most common cause
-Chronic intoxication by heavy metals (primarily lead) or various organic chemicals
-Congenital erythropoietic porphyria, a rare autosomal recessive porphyria caused by deficient uroporphyrinogen III synthase
-Hepatoerythropoietic porphyria, a rare autosomal recessive porphyria caused by deficient uroporphyrinogen decarboxylase
Typically, the workup of patients with a suspected porphyria is most effective when following a stepwise approach. See Porphyria (Acute) Testing Algorithm and Porphyria (Cutaneous) Testing Algorithm or call 800-533-1710 to discuss testing strategies.
There are 2 test options:
-PPFE / Protoporphyrins, Fractionation, Whole Blood
-PPFWE / Protoporphyrins, Fractionation, Washed Erythrocytes
The whole blood option is easiest for clients but requires that the specimen arrive at Mayo Clinic Laboratories within 7 days of collection. When this cannot be ensured, washed frozen erythrocytes, which are stable for 14 days, should be submitted.
FREE PROTOPORPHYRIN
<20 mcg/dL
ZINC-COMPLEXED PROTOPORPHYRIN
<60 mcg/dL
Abnormal results are reported with a detailed interpretation that may include an overview of the results and their significance, a correlation to available clinical information provided with the specimen, differential diagnosis, and recommendations for additional testing when indicated and available.
Patients must abstain from alcohol for at least 24 hours prior to specimen collection. Alcohol suppresses enzyme activity potentially leading to false-positive results.
1. Tortorelli S, Kloke K, Raymond K. Disorders of porphyrin metabolism. In: Dietzen DJ, Bennett MJ, Wong EDD, eds. Biochemical and Molecular Basis of Pediatric Disease. 4th ed. AACC Press; 2010:307-324
2. Phillips JD. Heme biosynthesis and the porphyrias. Mol Genet Metab. 2019;128(3):164-177. doi:10.1016/j.ymgme.2019.04.008
3. Anderson KE, Sassa S, Bishop DF, Desnick RJ. Disorders of heme biosynthesis: X-Linked sideroblastic anemia and the porphyrias. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed September 6, 2024. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225540906&bookid=2709
4. Whatley SD, Ducamp S, Gouya L, et al. C-terminal in the ALAS2 gene lead to gain of function and cause X-linked dominant protoporphyria without anemia or iron overload. Am J Hum Genet. 2008;83(3):408-414
Extraction followed by fractionation by high-performance liquid chromatography. Zinc protoporphyrin and free protoporphyrin are separately quantitated.(Smith RM, Doran D, Mazur M, Bush B. High-performance liquid chromatographic determination of protoporphyrin and zinc protoporphyrin in blood. J Chromatogr.1980;181[3-4]:319-327; Gou EE, Balwani M, Bissell DM, et al. Pitfalls in erythrocyte protoporphyrin measurement for diagnosis and monitoring of protoporphyrias. Clin Chem. 2015;61[12]:1453-1456. doi:10.1373/clinchem.2015.245456)
Monday through Friday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
82542
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
PPFE | Protoporphyrins, Fractionation, WB | 94490-0 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
2327 | Zinc-Complexed Protoporphyrin | 2895-1 |
2326 | Free Protoporphyrin | 94491-8 |
29511 | Interpretation | 59462-2 |