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Homocysteine (Serum) – Quantitative Measurement

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of homocysteine, a type of amino acid, in your blood. Elevated levels may indicate an increased risk of certain health conditions.

Quick summary

["Homocysteine levels can help assess your risk for heart disease or blood vessel problems."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
30035-0
Short code
Deprecated (Hcys)2 p fast SerPl-sCnc
Synonyms
Deprecated (Hcys)2 p fast SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84484
SNOMED
302774002
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

What Is Homocysteine?

Homocysteine is an amino acid that your body produces naturally as part of normal metabolism. While small amounts are normal, higher-than-usual levels may suggest a need for further evaluation, especially if you have risk factors for vascular diseases.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms like fatigue, numbness, or if you have a history of heart disease, stroke, or kidney problems. It can also be part of routine screening for individuals with genetic conditions or those on certain medications.

How Is the Test Performed?

A small blood sample is drawn from a vein in your arm. The blood is processed to separate serum (the liquid part) and then analyzed for homocysteine levels using a specialized laboratory method.

What Do Results Mean?

Results are typically reported as a concentration value (e.g., micromoles per liter). While reference ranges vary by lab, elevated results may prompt further testing or discussions about lifestyle changes, dietary adjustments, or medications to help lower levels.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Elevated Homocysteine Levels

Short name

Homocysteine

Frequently asked questions

What are the normal results for this test?
Normal results depend on the lab’s reference range, but generally, homocysteine levels are considered within a specific range (e.g., 5–15 µmol/L). If your results fall outside this range, your doctor may recommend additional tests or treatments to address potential underlying causes, such as vitamin deficiencies (e.g., folate or B12) or genetic factors.
How can I lower my homocysteine levels if they are high?
Lifestyle changes like eating a balanced diet rich in folate, vitamin B6, and vitamin B12, exercising regularly, and avoiding smoking can help. Your doctor may also prescribe supplements or medications if needed.
Does this test require fasting?
No fasting is typically required for this test, but always follow your healthcare provider’s instructions for best results.
  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 17, 2026. · Read our editorial policy