lab metric
Homocysteine
Table of contents
Description
Homocysteine is an amino-acid intermediate involved in “one‑carbon” metabolism—pathways that depend on B‑vitamins like folate (B9), B12, and B6. It’s commonly used as a marker of methylation-related nutrient status and, in some contexts, vascular risk.
Why it matters
Higher homocysteine is associated (in observational research) with higher cardiovascular risk and cognitive outcomes, and it can be a sign of inadequate folate/B12 status or impaired metabolism. It also rises when kidney function is reduced because the kidneys help clear homocysteine.
Common reasons homocysteine is higher
Low or borderline B12/folate/B6
Reduced kidney function (higher creatinine/lower eGFR)
Smoking, chronic inflammation, hypothyroidism
Certain medications (for example methotrexate)
Practical interpretation
If homocysteine is elevated, clinicians often interpret it with B12, methylmalonic acid (if available), folate, and kidney markers. In many cases, correcting deficiency and rechecking can clarify whether it’s a persistent issue.
Educational only, not medical advice. Supplement decisions and target ranges should be individualized with a clinician, especially if there’s kidney disease or neurologic symptoms.
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