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Serum or plasma concentration of **homocysteine** (via immunoassay)

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

This test measures the amount of homocysteine, an amino acid found in your blood. High levels may indicate an increased risk of certain health issues.

Quick summary

["Homocysteine levels can help assess your risk for heart disease or blood vessel problems."]

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

Key facts at a glance

LOINC
25777-4
Short code
GH 40M p chal SerPl-sCnc
Synonyms
GH 40M p chal SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is This Test Done?

Your healthcare provider may order this test if you have a history of heart disease, blood vessel problems, or certain genetic conditions. It may also be used to monitor treatment for conditions like vitamin deficiencies (e.g., folate or B12) that can affect homocysteine levels.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. Avoid smoking or consuming alcohol for a few hours beforehand if instructed.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood is then sent to a lab for analysis.

What to Expect After the Test

You can resume your normal activities immediately. There may be mild bruising or soreness at the injection site, but this usually goes away quickly. Call your provider if you experience excessive bleeding or signs of infection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Homocysteine Level

Frequently asked questions

What Does a High or Low Level Mean?
High homocysteine levels may increase the risk of cardiovascular diseases, such as heart attacks or strokes, by damaging blood vessels. It can also be linked to nerve or blood vessel damage (peripheral neuropathy) or kidney disease. Low levels are less commonly associated with health concerns but may indicate normal metabolic function.
How Does This Test Relate to Other Tests?
Homocysteine testing is often used alongside other blood tests, such as those for folate, vitamin B12, or cholesterol, to assess overall cardiovascular risk. Your provider may also check for conditions like homocystinuria (a rare genetic disorder).
Can Lifestyle or Diet Affect Results?
Yes! Certain foods, vitamins, and medications can influence homocysteine levels. Eating foods rich in folate, vitamin B6, and vitamin B12 (e.g., leafy greens, nuts, eggs) may help lower levels. Smoking, excessive alcohol, or certain medications (like some blood thinners) can also impact results.
  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