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Homocysteine, Total (Substance Concentration in Serum)

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

This test measures the amount of homocysteine, a type of amino acid (protein-building block) in your blood. High levels may be linked to certain health risks.

Quick summary

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

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

Key facts at a glance

LOINC
32020-0
Short code
Hcys Ur-sCnc
Synonyms
Hcys Ur-sCnc
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 Might This Test Be Ordered?

Your healthcare provider may recommend this test if you have a history of heart disease, stroke, kidney disease, or if you’re taking certain medications (like folic acid, vitamin B12, or B6 supplements). It may also be checked during routine blood work or if you have symptoms like fatigue, numbness, or joint pain.

What Does the Test Measure?

Homocysteine is a breakdown product of proteins. Elevated levels can damage blood vessel walls and increase the risk of blood clots, which can lead to heart attacks or strokes. This test helps monitor whether your levels are within a healthy range.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure homocysteine concentration. Results are typically available within a few days.

What Are Common Causes of High or Low Levels?

High homocysteine levels can be caused by genetic factors, certain medications, or deficiencies in vitamins like folate, vitamin B12, or vitamin B6. Low levels are less common but may occur with severe vitamin deficiencies or certain genetic disorders.

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 for me?
A high homocysteine level suggests an increased risk of blood clots or damage to blood vessels. Your doctor may recommend lifestyle changes (like a heart-healthy diet) or vitamin supplements (if deficiencies are confirmed) to help lower it. Follow-up tests may be needed to track progress.
Can I lower my homocysteine levels naturally?
Yes! Eating foods rich in folate (leafy greens, beans), vitamin B12 (meat, dairy), and vitamin B6 (whole grains, nuts) may help. Avoid excessive alcohol, maintain a healthy weight, and exercise regularly. Always check with your doctor before making major dietary changes.
Do I need to prepare for this test?
No special preparation is needed, but avoid heavy meals or alcohol 24 hours before the test. If you’re on medications like folic acid or vitamin B12 supplements, let your lab know to avoid interference.
  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