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Homocysteine, Serum Concentration

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

This test measures the level of homocysteine, a type of amino acid (a building block of proteins) found in your blood.

Quick summary

["Homocysteine levels may help assess risk for certain health conditions."]

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

Key facts at a glance

LOINC
44375-4
Short code
Hcys Bld Ql
Synonyms
Hcys Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is Homocysteine?

Homocysteine is an amino acid that your body produces naturally. While it plays a role in protein synthesis and metabolism, high levels can be linked to increased risk for cardiovascular diseases, nerve damage, and other health issues. Your body usually breaks down homocysteine, but certain factors—like diet, genetics, or health conditions—can keep it elevated.

Why Might You Need This Test?

Doctors may order a homocysteine test if you have a history of heart disease, stroke, nerve problems, or if you have conditions like kidney disease, vitamin deficiencies (such as folate or B12), or if you’re at higher risk for blood clots. It can also be part of routine screening in some cases.

How Is the Test Done?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab to measure homocysteine levels using an immunoassay method, which detects the presence of the amino acid in your serum.

What Do Results Mean?

Results show your homocysteine concentration in micromoles per liter (µmol/L). While reference ranges vary by lab, high levels (above typical ranges) may signal increased risk for complications. Your doctor will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated homocysteine levels are associated with an increased risk of cardiovascular diseases, such as heart attacks and strokes, due to damage to blood vessels and the formation of blood clots. It may also contribute to nerve damage (neuropathy) or osteoporosis. Managing risk factors like diet, exercise, and medications (such as folate, vitamin B6, or B12) can help lower levels.

Short name

Homocysteine

Frequently asked questions

What causes elevated homocysteine levels?
Several factors can raise homocysteine levels, including poor diet (low in folate, vitamin B6, or B12), kidney disease, smoking, alcohol use, certain medications (like some antidepressants or diuretics), and genetic conditions.
How can I lower my homocysteine levels?
Lifestyle changes like eating a balanced diet rich in folate (leafy greens, beans), vitamin B6 (nuts, whole grains), and vitamin B12 (meat, dairy, fortified foods) can help. Quitting smoking, reducing alcohol, and staying physically active may also support lower levels. Always consult your doctor before making changes or starting new supplements.
Is this test painful?
The blood draw is typically mild discomfort for a few seconds, similar to a standard blood test. Most people experience minimal pain afterward. If you have a hard time with needles, your doctor may use a smaller needle or apply a numbing cream.
  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