Preferred test for analysis of erythrocyte porphyrins. Establishing a biochemical diagnosis of erythropoietic protoporphyria, and X-linked dominant protoporphyria.
PORPHYRINS, TOTAL, RBC: <80 mcg/dL packed cells; FREE PROTOPORPHYRIN: <20 mcg/dL packed cells; ZINC-COMPLEXED PROTOPORPHYRIN: <60 mcg/dL packed cells.
5 - 9 days
- Porphyrin Evaluation, Washed Erythrocytes
Patient should abstain from alcohol for 24 hours prior to specimen collection. Collect blood in a green top tube. Place on wet ice immediately. Process 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 washed erythrocytes into a plastic vial and freeze.
Volume of packed cells and total volume of erythrocyte suspension (red cells + saline) are required and must be sent with specimen. Include a list of medications the patient is currently taking.
Place on ice immediately following collection. See below for processing instructions. (Pass to Chem along with Mayo instructions)
Test sent to Mayo Medical Laboratories.