One 7.5 mL serum separator tube (SST). Fasting specimen recommended. Also acceptable: One 5 mL red top tube or one 4 mL green top tube (heparin).
Allow to clot, centrifuge and separate serum or plasma within 2 hours. Folate is a light-sensitive analyte. Protect the specimen from light. Frozen specimens preferred. Specimens refrigerated up to 24 hours are also acceptable. Freeze if specimen cannot be assayed within 24 hours. If a frozen specimen is submitted, separate tubes must be sent for multiple tests. Allow no more than one freeze/thaw cycle.
0.5 mL serum or heparinized plasma.
200 µL serum or heparinized plasma.
Refrigerated if received in laboratory within 24 hours of collection, or frozen on dry ice.
Moderate to gross hemolysis; EDTA specimen; specimen frozen/thawed more than once; refrigerated specimen received in laboratory more than 24 hours after collection.