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Homocysteine, Total, Serum or Plasma

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

This test measures the level of homocysteine, an amino acid in your blood that can be linked to certain health risks.

Quick summary

["Homocysteine levels may 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
54301-7
Short code
Hcys DBS-sCnc
Synonyms
Hcys DBS-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, stroke, or blood vessel problems, or if you have symptoms like fatigue, numbness, or tingling in your hands or feet. It may also be used to monitor treatment for conditions like vitamin deficiencies or certain genetic disorders.

What Does the Result Mean?

Results are not provided with specific numeric ranges since reference values can vary by lab and individual health. High levels may indicate increased risk for vascular issues, while low levels may suggest deficiencies in vitamins B6, B9, or B12.

How Is This Test Performed?

A blood sample is taken from a vein in your arm. You may feel a small pinch when the needle is inserted, but the procedure is quick and usually not painful. The sample is sent to a lab for analysis using an immunoassay method to measure homocysteine concentration.

What Are Common Causes of Abnormal Results?

Elevated homocysteine levels can be caused by genetic factors, certain medications (like some blood thinners or diuretics), kidney disease, or deficiencies in vitamins B6, B9, or B12. Low levels may result from overconsumption of certain supplements or specific medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Homocysteine

Frequently asked questions

How often will I need this test?
This test may be done once or multiple times depending on your health status, symptoms, or treatment plan. Your healthcare provider will determine the frequency based on your individual needs and medical history.
What do I do if my homocysteine levels are high?
If your levels are elevated, your healthcare provider may recommend lifestyle changes (such as a balanced diet rich in folate, vitamin B6, and B12), vitamin supplements, or further evaluation to address underlying conditions like kidney disease or vitamin deficiencies.
Can I eat or drink anything before this test?
Typically, you should fast for 8–12 hours before this test unless instructed otherwise by your healthcare provider. Avoid alcohol and certain medications that may affect results. Follow your provider’s specific instructions.
  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