Patient should abstain from alcohol for 24 hours and be off medications for 1 week prior to specimen collection. If it is clinically inappropriate to discontinue medications, forward a list of medications with the specimen. Collect blood in a green top tube from a fasting patient (12 - 14 hour fast). Place on wet ice immediately. Process as follows:
a. Transfer entire specimen to a 12-mL graduated centrifuge tube.
b. Centrifuge specimen for 10 minutes at 2,000 rpm.
c. Record volume of packed cells and the total volume of the specimen.
d. Discard supernatant plasma.
e. 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.
f. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.
g. 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.