Is my Homocysteine normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal Homocysteine level?
Homocysteine is an amino acid produced during protein metabolism. It's normally converted to methionine (using B12 and folate) or cysteine (using B6). When these vitamins are deficient or MTHFR gene variants are present, homocysteine accumulates. Elevated levels damage blood vessel walls and increase risk of heart disease, stroke, and dementia.
| Range | Values |
|---|---|
| Standard Reference | 4–10 µmol/L |
| Optimal | 4–8 µmol/L |
| Longevity Optimal | < 8 µmol/L |
| High Risk | > 15 µmol/L |
What causes abnormal Homocysteine levels?
Elevated homocysteine is caused by deficiencies in B12, folate, or B6 (the vitamins needed to metabolize it), MTHFR gene variants (especially C677T — present in 10-15% of the population), chronic kidney disease (impaired excretion), hypothyroidism, smoking, excessive coffee consumption, and medications that interfere with B-vitamin metabolism.
When should you see a doctor?
See your doctor if homocysteine is above 10 µmol/L, especially with a family history of early heart disease or stroke. If above 15 µmol/L, request B12, folate, B6, and MTHFR testing. In the context of cognitive decline, elevated homocysteine should be aggressively treated with B-vitamin supplementation.
Homocysteine and longevity
Homocysteine is a direct marker of one-carbon metabolism efficiency and a powerful independent predictor of cardiovascular events, stroke, and cognitive decline. Elevated homocysteine damages the vascular endothelium, promotes thrombosis, and impairs nitric oxide production. The VITACOG trial demonstrated that B-vitamin supplementation (B12, folate, B6) slowed brain atrophy by 30% in elderly patients with elevated homocysteine — one of the few interventions shown to slow structural brain aging. MTHFR C677T homozygosity (TT genotype, ~10-15% of the population) is the most common genetic cause of elevated homocysteine and responds well to methylfolate supplementation. Targeting homocysteine below 8 µmol/L is a core longevity strategy that is inexpensive and highly modifiable.
Where to get a Homocysteine test
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Related biomarkers
These biomarkers are often tested alongside Homocysteine for a more complete picture.
Frequently asked questions
What is a normal homocysteine level?
What causes high homocysteine?
How do I lower homocysteine?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.