Methymalonic Acid and Homocysteine Quant

LAB5210020

91003

2.7 mL serum

1.1 mL

Serum collected in: Trace metal-free (royal blue-top) tube • Plasma collected in: Sodium heparin (green-top) or sodium heparin trace element free (royal blue-top) tube

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.

Refigerated (cold packs)

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 6 months

Gross hemolysis • Grossly lipemic • Whole blood • Unseparated serum or plasma

See indiviual assays

Methylmalonic Acid	87-318 nmol/L
Homocysteine
Male	<11.4 umol/L
Female	<10.4 umol/L

Homocysteine is increased by functional deficiency of folate or vitamin B12. Testing for methylmalonic acid differentiates between these deficiencies. Other causes of increased homocysteine include renal failure, folate antagonists such as methotrexate and phenytoin, and exposure to nitrous oxide. Selhub J, et al., Ann Intern Med. 1999;131(5):331-9.

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).