Homocysteine (fasting) - Serum or Plasma Concentration
This test measures the level of homocysteine, an amino acid in your blood that may be linked to certain health risks if levels are too high.
["High homocysteine levels may increase your risk of heart disease or blood vessel damage."]
Key facts at a glance
- LOINC
- 72500-2
- Short code
- Hcys p fast SerPl-sCnc
- Synonyms
- Hcys p fast SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have a history of heart disease, blood vessel issues, or certain genetic conditions. It could also be part of routine screening if you have risk factors like high blood pressure, diabetes, or kidney problems. Sometimes, it’s checked after a stroke or heart attack to assess risk factors.
What to Expect Before the Test
For this test, you’ll need to fast for 12–14 hours before drawing blood. Avoid eating or drinking anything except water. Your provider will give you specific instructions if you’re on certain medications or have dietary restrictions.
What the Test Involves
A healthcare professional will insert a small needle into your arm to draw blood from a vein. The process usually takes a few minutes, and you may feel a brief pinch. The blood sample will be sent to a lab for analysis.
What the Results Mean
Results are typically reported as a concentration of homocysteine in the blood. While reference ranges vary by lab, high levels may signal increased risk for vascular problems. Your provider will discuss results in the context of your overall health.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Homocysteine (fasting)
Frequently asked questions
What are the normal reference ranges for this test?
How often should I get this test?
Can I take supplements to lower homocysteine levels?
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 17, 2026. · Read our editorial policy