Metabolic
Homocysteine
LOINC 13965-9 · umol/L
What it is
Homocysteine is an amino acid in the blood. The body normally clears it with the help of B vitamins (B6, B12 and folate).
Why it matters
A raised level can flag a B-vitamin deficiency and is studied as a marker linked to cardiovascular and cognitive health.
What high values can mean
A higher value often reflects low B12, folate or B6, kidney issues, or genetic factors.
What low values can mean
A lower value is generally not a concern.
How to improve it
When driven by vitamin deficiency, correcting B12, folate and B6 typically lowers homocysteine.
Food & lifestyle
Leafy greens, legumes, eggs and fortified grains supply folate and B vitamins that help clear homocysteine.
Preparing for the testFasting required
Often measured fasting for accuracy — follow your lab's instructions.
When to talk to a doctor
Discuss a high homocysteine with a doctor, who may check your B-vitamin levels.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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