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Homocysteine, Total (Serum or Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of homocysteine, a type of amino acid, in your blood. Homocysteine can be linked to certain health risks.

Quick summary

["Your blood homocysteine levels may help assess heart disease or other health risks."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
59252-7
Short code
Hycs-Cys diS CSF-sCnc
Synonyms
Hycs-Cys diS CSF-sCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
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, stroke, or other vascular conditions. It might also be checked if you have symptoms like fatigue, numbness, or weakness, or if you’re taking certain medications that can affect homocysteine levels, such as folic acid or vitamin B supplements.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw. Avoid smoking or consuming alcohol for at least 24 hours before testing.

What the Test Involves

A small needle will be used to draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause much discomfort. 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, higher than normal levels may indicate an increased risk of blood vessel damage or heart disease. Your provider will discuss these results with you in detail.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Homocysteine

Frequently asked questions

What Does It Measure?
Homocysteine is an amino acid that plays a role in metabolism. Elevated levels can damage blood vessels over time, increasing the risk of heart disease, stroke, or peripheral artery disease. It’s also linked to certain genetic conditions.
How Might It Affect My Health?
High homocysteine levels may raise concerns about long-term vascular health. Your doctor might suggest lifestyle changes, such as diet adjustments (rich in folate, vitamin B6, and vitamin B12), or medications to help lower levels if needed.
Could This Test Be Affected by Medications?
Yes, certain medications—like folic acid supplements, vitamin B12, or B6—can lower homocysteine levels. Always inform your provider about all medications or supplements you’re taking before testing.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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