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Homocysteine, Plasma (Total)

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

This test measures the amount of homocysteine, a type of amino acid (a building block of proteins) found in your blood plasma. It helps assess your risk for certain health conditions.

Quick summary

["Homocysteine levels can indicate risks for heart disease, blood vessel damage, or other health concerns."]

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

Key facts at a glance

LOINC
44376-2
Short code
Hcys DBS Ql
Synonyms
Hcys DBS Ql
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 doctor may order this test if you have a history of heart disease, blood vessel problems, or certain genetic conditions. It may also be checked if you’re taking certain medications (like folic acid or vitamin B supplements) or if you have symptoms like fatigue, numbness, or memory issues that could relate to high homocysteine levels.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood. The process usually takes a few minutes, and you may feel a brief pinch. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Higher-than-normal homocysteine levels may suggest an increased risk of blood vessel damage or heart disease. Lower-than-normal levels might indicate a need for additional vitamin checks (like folate or B12). Your doctor will discuss results in the context of your overall health.

Common Reasons for Testing

Doctors often check homocysteine levels in patients with vascular diseases, stroke risk, or those with conditions like diabetes or kidney disease. It’s also used to monitor treatment responses for certain genetic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Homocysteine and Health Risks

Short name

Homocysteine

Frequently asked questions

What causes elevated homocysteine levels?
Elevated homocysteine can be caused by genetic factors, certain medications, low vitamin levels (like folate or B12), kidney disease, or metabolic conditions. Lifestyle factors, such as smoking or poor diet, may also play a role.
Can homocysteine levels be lowered?
Yes, lifestyle changes (like a balanced diet rich in folate, vitamin B, and antioxidants) and sometimes supplements can help lower homocysteine. Your doctor may also adjust medications if needed.
Are there symptoms of high homocysteine?
High homocysteine often doesn’t cause symptoms early on, but long-term risks include heart disease, stroke, or nerve damage. If you have symptoms like fatigue, numbness, or memory issues, discuss them with your doctor—this test may help investigate.
  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