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Homocysteine (Total) in 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. High levels may be linked to certain health risks.

Quick summary

["Homocysteine levels can help assess your risk for heart disease and other conditions."]

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

Key facts at a glance

LOINC
54299-3
Short code
Homocitrulline Amn-sCnc
Synonyms
Homocitrulline Amn-sCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend this test if you have a history of heart disease, stroke, blood vessel problems, or if you have conditions like kidney disease, vitamin deficiencies (such as folate or B12), or certain genetic disorders. It may also be checked during routine health screenings or if you’re taking medications that can affect homocysteine levels.

How the Test Works

A small blood sample is taken from your arm and sent to a lab. The lab uses a specialized method (often an immunoassay or chromatography) to measure the total homocysteine concentration in your blood plasma or serum.

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 test if instructed by your doctor. Avoid smoking or consuming alcohol for a short time before your blood draw.

What to Expect During the Test

You’ll lie down on a table while a healthcare provider inserts a small needle into your arm. A small amount of blood is collected into a test tube. The process is quick and typically causes only minor discomfort.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Homocysteine

Frequently asked questions

What does a high homocysteine level mean?
A high homocysteine level may signal an increased risk of heart disease, stroke, or other vascular problems. Your doctor may recommend lifestyle changes, dietary adjustments (such as increasing folate, vitamin B6, and vitamin B12), or further testing to address underlying causes like vitamin deficiencies or kidney issues.
What causes homocysteine levels to be high?
High homocysteine levels can be caused by genetic factors, certain medications (like some antidepressants or diuretics), kidney disease, vitamin deficiencies (folate, vitamin B6, or B12), smoking, heavy alcohol use, or conditions like diabetes.
How can I lower my homocysteine levels?
To potentially lower homocysteine levels, focus on a balanced diet rich in folate (leafy greens, beans), vitamin B6 (whole grains, nuts), and vitamin B12 (meat, dairy, fortified foods). Stay hydrated, avoid smoking, limit alcohol, and consult your doctor about supplements if needed. Regular exercise and managing conditions like diabetes also play a role.
  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