Homocysteine CPT: 83090

Expected Turnaround Time

Within 1-2 days

Specimen Requirements


Plasma (preferred); serum is acceptable.


2 mL

Minimum Volume

1 mL


Plasma: It is important to centrifuge blood samples for plasma collection immediately after collection to separate the plasma from the blood cells. If immediate centrifugation is not possible, collected blood specimens should be kept on ice and centrifuged within an hour.

Serum:Allow 45 minutes for serum to clot and centrifuge to separate serum from cells immediately thereafter.


If tube other than a gel-barrier tube is used, transfer separated serum or plasma to a plastic transport tube.

Storage Instructions

Temperature Period
Room Temperature3 Days
Refrigerated10 Days
Frozen1 Months
Freeze/thaw/ cycles X 3

Patient Information

Patient Preparation

A fasting specimen is preferred to establish baseline values or monitor treatment.

To help determine if you are deficient in vitamins B6, B9 (folate) or B12; to determine if you are at increased risk of heart attack or stroke; to monitor those who have heart disease; sometimes to help diagnose a rare inherited disorder called homocystinuria in newborns.

When your healthcare provider suspects that you have a vitamin B6, B12 or folate deficiency; when you have had a heart attack or stroke and do not have traditional risk factors, such as unhealthy lipid levels.

A blood sample taken by needle from a vein.

You may be instructed to fast for 10 to 12 hours prior to this test; only water is permitted.