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Test Code PEWE Porphyrins Evaluation, Washed Erythrocytes

Reporting Name

Porphyrin Evaluation, RBC

Useful For

Preferred test for analysis of erythrocyte porphyrins

 

Establishing a biochemical diagnosis of erythropoietic protoporphyria, and X-linked dominant protoporphyria

Testing Algorithm

This test is recommended for screening patients for possible erythropoietic protoporphyria and X-linked dominant protoporphyria. In addition, it can be used for evaluation of iron-deficiency anemia and chronic lead intoxication. Testing begins with total erythrocyte porphyrins. If the result is below 80 mcg/dL, it is normal, and testing is complete.

 

If the total erythrocyte porphyrin value is 80 mcg/dL or above, the protoporphyrin fractionation assay will automatically be performed at an additional charge. The fractionation test results include noncomplexed (free) protoporphyrin and zinc-complexed protoporphyrin.

 

The following algorithms are available:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Washed RBC


Ordering Guidance


This is the preferred test for assessment for protoporphyria. The preferred test for assessing 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 draw 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 to a plastic tube 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

Reference Values

PORPHYRINS, TOTAL, RBC

<80 mcg/dL

Day(s) Performed

Monday through Friday

Test Classification

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.

CPT Code Information

84311-Spectrophotometry, analyte not elsewhere specified

82542-Chromatography (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PEWE Porphyrin Evaluation, RBC 2814-2

 

Result ID Test Result Name Result LOINC Value
31942 Total Porphyrins, RBC 2814-2
31943 Interpretation 59462-2
BG569 Total cell suspension 94496-7
BG570 Packed cell volume 94497-5

Report Available

3 to 5 days

Method Name

Spectrofluorometric