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Homocysteine
Test Code31789
CPT Codes
83090
Preferred Specimen
1 mL serum
Minimum Volume
0.5 mL
Other Acceptable Specimens
Serum in royal blue trace metal free tube • Plasma in sodium heparin (green-top) or EDTA (lavender-top) or Royal blue-top (sodium heparin) trace element free w/green band
Instructions
Red top tubes: Place the specimen in a refrigerator or ice bath for 30 minutes after collection. Centrifuge the specimen as soon as possible after complete clot formation has taken place. Transfer the serum to a plastic screw-capped vial.
Barrier gel separator tubes: Place the specimen in a refrigerator for 30 minutes after collection. Centrifuge the specimen as soon as possible after complete clot formation has taken place. Do not place barrier tubes in an ice bath as freezing may prevent the barrier gel from adequately separating serum from cells.
EDTA or heparin tubes: Place the specimen in a refrigerator or ice bath until the specimen can be centrifuged. Centrifuge the specimen as soon as possible and transfer the plasma to a plastic screw-capped vial.
Royal blue-top serum and royal blue-top sodium heparin are acceptable containers. Instructions for collecting blood in royal blue-top serum tube are similar to red top or serum separator tube tubes and sodium heparin tubes.
Barrier gel separator tubes: Place the specimen in a refrigerator for 30 minutes after collection. Centrifuge the specimen as soon as possible after complete clot formation has taken place. Do not place barrier tubes in an ice bath as freezing may prevent the barrier gel from adequately separating serum from cells.
EDTA or heparin tubes: Place the specimen in a refrigerator or ice bath until the specimen can be centrifuged. Centrifuge the specimen as soon as possible and transfer the plasma to a plastic screw-capped vial.
Royal blue-top serum and royal blue-top sodium heparin are acceptable containers. Instructions for collecting blood in royal blue-top serum tube are similar to red top or serum separator tube tubes and sodium heparin tubes.
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 4 days
Refrigerated: 14 days
Frozen: 6 months
Refrigerated: 14 days
Frozen: 6 months
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly lipemic • Unseparated serum or plasma • Whole blood specimens
Methodology
Enzymatic
Setup Schedule
Set up: Mon-Fri; Report available: 3-6 days
Clinical Significance
An elevated concentration of homocysteine is an independent risk factor for cardiovascular disease. When used in conjunction with methylmalonic acid (MMA), these tests are useful to diagnose and monitor vitamin B12 (cobalamin) and folic acid deficiency and are often useful in evaluating macrocytosis (an elevated MCV, an erythrocytic index).
