Homocysteine, Total, Plasma
Use
This test aids in screening for patients suspected of having inherited disorders of methionine metabolism, such as cystathionine beta-synthase deficiency (homocystinuria), methylenetetrahydrofolate reductase deficiency, methionine synthase deficiency, and several cobalamin (vitamin B12) metabolism disorders. It's also useful in evaluating individuals with suspected deficiency of vitamin B12 or folate. Homocysteine levels can be an indicator of acquired folate or cobalamin deficiency and are occasionally used in the assessment of cardiovascular risk, although its role in this context is controversial.
Special Instructions
Patient's age and sex are required. Wet ice should be used for the immediate placement of the specimen, and plasma aliquoting should occur within 4 hours if the blood cannot be immediately cooled.
Limitations
While homocysteine levels can be an indicator of vitamin B12 or folate deficiency, the test should not be solely relied upon for the assessment of cardiovascular risk due to its controversial status as a risk factor for coronary heart disease. The test should be part of a comprehensive evaluation including plasma amino acids, acylcarnitines, methylmalonic acid, and urine organic acids. Accurate measurement requires adherence to strict specimen handling protocols, such as immediate cooling and timely plasma separation.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.4 mL
Container
Plastic vial
Collection Instructions
Immediately place specimen on wet ice. Within 4 hours of collection, centrifuge and aliquot plasma into a plastic vial.
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus are acceptable.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 309 days |