Homocysteine (Serum)
This test measures the level of homocysteine, a type of amino acid (a building block of proteins) found in your blood.
["Homocysteine levels may help assess risks for certain health conditions."]
Key facts at a glance
- LOINC
- 26809-4
- Short code
- (Hcys)2 24h Ur Ql
- Synonyms
- (Hcys)2 24h Ur Ql
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for conditions linked to high homocysteine levels, such as heart disease, stroke, or certain genetic disorders. It may also be used as part of routine screening or to monitor treatment for conditions like vitamin deficiencies (e.g., folate or B12).
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s done on an empty stomach, but always confirm with your provider. Avoid smoking or consuming alcohol for a few hours beforehand. Bring any medications you’re taking to your appointment.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but it’s usually over quickly. The blood sample is sent to a lab for analysis. The test typically takes a few minutes to complete.
What Does the Test Result Mean?
Results are not provided with specific numeric ranges on this site. Your provider will interpret the result in relation to your health history and other test results. High levels may signal increased risk for vascular issues, while low levels may indicate deficiencies in certain vitamins.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Homocysteine
Frequently asked questions
High homocysteine levels can contribute to damage in blood vessels, increasing the risk of heart disease, stroke, or peripheral artery disease. It may also be linked to certain genetic disorders or vitamin deficiencies (e.g., folate or B12). Your provider may recommend lifestyle changes, supplements, or further testing if results are elevated.
The frequency depends on your health status and risk factors. If you have a history of high homocysteine, heart disease, or vitamin deficiencies, your provider may recommend testing every 1–2 years. Otherwise, it’s often done as part of a routine cardiovascular or metabolic health check.
High homocysteine levels can be caused by genetic factors, certain medications (e.g., some chemotherapy drugs), kidney disease, or deficiencies in vitamins B6, B12, or folate. Lifestyle factors like smoking, alcohol use, or poor diet may also play a role.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy