Patient Preparation Fasting for at least 8 hours is preferred
Preferred Specimen(s) 1 mL serum or EDTA plasma
Instructions
EDTA plasma: Place the specimen in the refrigerator or ice bath until the specimen can be centrifuged. Centrifuge the specimen as soon as possible and separate the plasma to plastic screw cap vial
Red-top tube: Place the specimen in the refrigerator or ice bath for 30 minutes after collection. Centrifuge the specimen as soon as possible after complete clot formation. Transfer the serum to a plastic specimen transport tube. Mark the specimen type as serum on the transport tube.
Barrier gel separator tube: Place the specimen in a refrigerator for 30 minutes after collection. Do not place barrier tubes in an ice bath as freezing may prevent the barrier gel from adequately separating serum from cells. Centrifuge specimen as soon as possible after complete clot formation, ensuring that the barrier gel completely separates serum from cells.
Note: It is very important to centrifuge and separate serum or plasma from red blood cells as soon as possible to avoid falsely elevated results
Transport Container Plastic screw-cap vial
Transport Temperature
- Frozen 3 months,
- Refrigerated 14 days
Reject Criteria
- Gross hemolysis
- Unseparated serum or plasma
- Whole blood specimens
Methodology Chemiluminescence
Clinical Significance Diagnose and monitor treatment of homocystinuria, folate deficiency, or vitamin B12 deficiency.