One 7.5 mL serum separator tube (SST). Also acceptable: One 4 mL green top tube (sodium heparin). Patient should be fasting.
Handling:
Allow to clot, centrifuge and separate serum or plasma from cells into a plastic vial. Freeze. If multiple tests are ordered, send separate specimen for this test.
Stability:
Specimen stable 3 hours ambient or refrigerated, or 1 week frozen.