Homocysteine
Homocysteine is an amino acid produced in normal metabolism. Vitamins B12, B6, and folate are needed to keep its levels in check. Elevated homocysteine damages blood vessel linings and is an independent risk factor for heart attack, stroke, and venous thromboembolism. It is also associated with cognitive decline and pregnancy complications.
Reference Ranges
Male
5 – 15
µmol/L
Female
5 – 15
µmol/L
Child
5 – 12
µmol/L
Ages 6–12
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
Low homocysteine is not clinically significant and is considered desirable. Very low values have no known adverse consequences.
What High Levels Mean
Homocysteine 15–30 µmol/L is moderate elevation — usually due to B12 or folate deficiency, kidney disease, or the MTHFR gene variant. Levels above 30 µmol/L are substantial and warrant evaluation. Above 100 µmol/L suggests the rare genetic disorder homocystinuria and needs urgent specialist referral.
Frequently Asked Questions
Should everyone get a homocysteine test?
No. Routine screening is not recommended. Testing is appropriate for: early or unexplained cardiovascular disease, unexplained thrombosis, recurrent pregnancy loss, a family history of premature heart disease, or suspected B12/folate deficiency. Population-level screening does not improve outcomes.
Can I lower my homocysteine?
Yes. B12, folate, and B6 supplementation — or a diet rich in green leafy vegetables, legumes, and eggs — reliably lowers homocysteine. However, large trials (HOPE-2, NORVIT) have shown that lowering homocysteine with vitamins does NOT reduce heart attacks or strokes. Treat the underlying deficiency if present, but do not use vitamins purely to lower cardiovascular risk.
What is the link between MTHFR and homocysteine?
The MTHFR enzyme converts folate to its active form, needed to clear homocysteine. The C677T and A1298C gene variants reduce MTHFR activity and can raise homocysteine modestly, especially with low folate intake. Most people with MTHFR variants have normal homocysteine on an adequate diet and do not need special treatment.
Related Cardiac tests
See all →This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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