3 mL serum from a plain red top tube. Allow sample to clot in an upright position for at least 60 minutes, then centrifuge sample and transfer serum to a plastic transport tube within 2 hours of collection. Clearly label tube as serum from a plain red top tube. Freeze. When multiple tests are ordered, submit separate tube for this test.

3 mL EDTA (lavender top) plasma. Centrifuge sample and separate plasma from cells immediately. Transfer plasma to a plastic transport tube. Clearly label tube as EDTA plasma. Freeze. When multiple tests are ordered, submit separate tube for this test.