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Serum or plasma concentration of homocysteine

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

This test measures the amount of homocysteine, an amino acid, in your blood. It can help assess risks related to heart disease, blood vessel damage, or certain genetic conditions.

Quick summary

["Homocysteine levels may indicate risks for vascular health or genetic disorders."]

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

Key facts at a glance

LOINC
37717-6
Short code
XR tomo Hand-R
Synonyms
XR tomo Hand-R
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-tomography
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 This Test Might Be Ordered

Your doctor may recommend this test if you have a history of heart disease, stroke, or blood vessel problems, or if you have symptoms like fatigue, numbness, or joint pain. It’s also sometimes checked in people with kidney disease or those with a family history of genetic disorders like homocystinuria.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. Bring any medications you’re taking to your appointment.

How the Test Works

A blood sample is drawn from a vein in your arm. The sample is sent to a lab, where it’s analyzed to measure homocysteine levels using a sensitive immunoassay or enzymatic method.

What the Results Mean

Results are typically reported as a concentration (e.g., micromoles per liter). High levels may signal increased risk for vascular issues, while low levels are less concerning unless related to other conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Homocysteine Level

Frequently asked questions

High homocysteine levels can damage blood vessels over time, increasing the risk of heart disease, stroke, or peripheral artery disease. It may also be linked to certain genetic disorders like homocystinuria, which requires lifelong management.
This test helps doctors monitor and guide treatment for conditions like folate or vitamin B12 deficiencies, which can lower homocysteine levels.
FAQ 1: Can I eat or drink before this test?
If fasting is required (e.g., for a metabolic panel), avoid food and liquids except water for 8–12 hours before drawing blood. Otherwise, you can eat normally unless instructed otherwise.
FAQ 2: What causes high homocysteine levels?
High levels can result from genetic factors, poor diet (low in folate, vitamin B6, or B12), kidney disease, alcohol use, or certain medications (like some chemotherapy drugs). Lifestyle changes or supplements may help.
  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