Porphyrins Evaluation, Washed Erythrocytes
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
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 <80 mcg/dL, it is normal and testing is complete.
If the total erythrocyte porphyrin value is > or =80 mcg/dL, the protoporphyrin fractionation (PPFWE) assay will automatically be performed at an additional charge. The PPFWE test results include free protoporphyrin and zinc-complexed protoporphyrin.
The following algorithms are available in Special Instructions:
-Porphyria (Acute) Testing Algorithm
-Porphyria (Cutaneous) Testing Algorithm
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
All porphyrin tests on erythrocytes can be performed on 1 draw tube.
Preferred: Green top (sodium heparin)
Acceptable: Dark blue top (metal free heparin) or green top (lithium heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: Washed erythrocyte suspension
1. Patient should abstain from alcohol for 24 hours.
2. Collect and process whole blood specimen as follows:
a. Immediately place specimen on wet ice.
b. Transfer entire specimen to a 12-mL graduated centrifuge tube.
c. Centrifuge specimen for 10 minutes at 2,000 rpm.
d. Record volume of packed cells and the total volume of the specimen.
e. Discard supernatant plasma.
f. 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 2,000 rpm, discarding supernatant after each washing.
g. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.
h. Transfer to a plastic tube and freeze.
1. Volume of packed cells and total volume of erythrocyte suspension (red cells + saline) are required and must be sent with specimen.
2. Include a list of medications the patient is currently taking.
Forms: New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Cell suspension not available
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Washed RBC||Frozen (preferred)||14 days|