Allow sample to clot in an upright position for at least 30 minutes, then centrifuge sample. Refrigerate.
Alternative Specimen
0.5 mL serum from a plain red top tube. Allow specimen to clot completely for 20 to 30 minutes prior to centrifugation. Centrifuge at 1,600 RCF for 10 minutes. Using a transfer pipette remove the serum and transfer to a transfer tube and clearly label as serum from a plain red top tube. Refrigerate.
