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HelpTest Code PPFWE Protoporphyrins, Fractionation, Washed Erythrocytes
Reporting Name
Protoporphyrins, Fractionation, RBCUseful For
Preferred test for analysis of erythrocyte protoporphyrin fractions
Preferred test for evaluating patients with possible diagnoses of erythropoietic protoporphyria and X-linked dominant protoporphyria
Establishing a biochemical diagnosis of erythropoietic protoporphyria, or X-linked dominant protoporphyria
Testing Algorithm
This test should not be ordered in conjunction with PEWE / Porphyrins Evaluation, Washed Erythrocytes.
The following algorithms are available:
-Porphyria (Acute) Testing Algorithm
Method Name
High-Performance Liquid Chromatography (HPLC) with Fluorescence Detection
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Washed RBCOrdering Guidance
This test is for assessment for protoporphyria, an erythropoietic porphyria. 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.
Necessary Information
1. Volume of packed cells and total volume of specimen (red cells + saline) are required and must be sent with specimen.
2. Include a list of medications the patient is currently taking.
Specimen Required
All porphyrin tests on erythrocytes can be performed on 1 tube.
Patient Preparation: Patient must not consume any alcohol for 24 hours before specimen collection.
Collection Container/Tube:
Preferred: Green top (sodium heparin)
Acceptable: Dark blue top (metal free heparin), green top (lithium heparin), or lavender top (EDTA)
Submission Container/Tube: Plastic vial
Specimen Volume: Entire washed erythrocyte suspension
Collection Instructions: Collect and process whole blood specimen as follows:
1. Transfer entire specimen to a 12-mL graduated centrifuge tube.
2. Centrifuge specimen at 4° C for 10 minutes at 2000 rpm.
3. Record volume of packed cells and the total volume of the specimen.
4. Discard supernatant plasma.
5. Wash packed erythrocytes 2 times by resuspension of at least an equal amount of cold 0.9% saline, mix, and centrifuge for 5 minutes at 2000 rpm, discarding supernatant after each washing.
6. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.
7. Transfer washed erythrocytes into a plastic vial and freeze.
Specimen Minimum Volume
1 mL of washed and resuspended erythrocytes
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Washed RBC | Frozen (preferred) | 14 days | |
| Refrigerated | 14 days |
Reject Due To
| Cell suspension not available | Reject |
Special Instructions
Reference Values
FREE PROTOPORPHYRIN
<20 mcg/dL
ZINC-COMPLEXED PROTOPORPHYRIN
<60 mcg/dL
Day(s) Performed
Monday through Friday
CPT Code Information
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PPFWE | Protoporphyrins, Fractionation, RBC | 94490-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 31932 | Zinc-Complexed Protoporphyrin | 2895-1 |
| 31933 | Free Protoporphyrin | 94491-8 |
| INTP6 | Interpretation | 59462-2 |
| BG571 | Total cell suspension | 94496-7 |
| BG572 | Packed cell volume | 94497-5 |
Clinical Information
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, and total protoporphyrin 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.
Interpretation
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.
Cautions
Patients must abstain from alcohol for at least 24 hours prior to specimen collection. Alcohol suppresses enzyme activity potentially leading to false-positive results.
Method Description
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]:1453-6. doi:10.1373/clinchem.2015.245456)