Learn › Homocysteine
Homocysteine is an amino acid your body produces as an intermediate step in metabolism. Normally it is quickly converted into other compounds — a process that depends on vitamins B12, B6 and folate.
Reference range used: 5–15 µmol/L. Runs in your browser — nothing is stored.
When those vitamins are in short supply, or the pathway is impaired, homocysteine accumulates. That is what makes it useful: it is a functional marker of whether those pathways are actually working, not just whether the vitamins are present.
Raised homocysteine has been consistently associated with cardiovascular and cognitive outcomes in observational studies. Whether lowering it changes those outcomes is less settled — but it remains a reliable indicator of B-vitamin status.
Most laboratories use roughly 5–15 µmol/L as the normal range. Many researchers consider below 10 µmol/L preferable, though that is an optimal target rather than a clinical cut-off.
No. It is an associated marker, not a diagnosis. The association is consistent in observational research, but trials lowering homocysteine with vitamins have not reliably reduced cardiovascular events.
A gene affecting folate metabolism. Common variants reduce enzyme efficiency and can raise homocysteine. It is common in the general population and, on its own, is not a disease.
If a B-vitamin deficiency is the cause, correction typically shows within 6 to 12 weeks.
A single value tells you little on its own. PhisBio Lab reads your whole blood panel and shows how five body systems — including Heart — are doing together.
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