What is Homocysteine?
Homocysteine is an amino acid produced during normal metabolism and cleared with the help of vitamins B12, B6, and folate. When those vitamins are low or due to genetic and kidney factors homocysteine rises. Elevated homocysteine is associated with increased cardiovascular and cognitive risk.
Why it matters
High homocysteine is an independent marker linked to blood vessel damage, clot risk, and cognitive decline, and it often points to correctable B-vitamin deficiencies.
What it measures
Total plasma homocysteine concentration, often assessed alongside B12 and folate.
Reference & optimal ranges
Reference ranges vary by lab, assay, age, and sex. The ranges below reflect commonly published adult intervals and are for education only always interpret results with the range printed on your own lab report and a clinician.
High homocysteine is linked to cardiovascular and cognitive risk and frequently reflects low B12, folate, or B6.
Common symptoms
- Usually none directly
Potential causes
- Low B12, folate, or B6
- Kidney disease
- Hypothyroidism
- Genetic (MTHFR variants)
- Smoking, excess alcohol
Low homocysteine is generally favorable and not a concern.
Common symptoms
- None
Potential causes
- Good B-vitamin status
- Healthy metabolism
How to improve your Homocysteine
Lifestyle
Limit smoking and excess alcohol
Both raise homocysteine.
Nutrition
Ensure adequate B vitamins
Folate, B12, and B6 from food or supplements lower elevated homocysteine when deficiency is the cause.
Exercise
Regular activity
Supports cardiovascular health alongside homocysteine management.
Sleep
General health
Supports overall metabolic wellness.
Frequently asked questions
Scientific references
- Homocysteine Test MedlinePlus, U.S. National Library of Medicine
- Homocysteine Test Testing.com
Educational information, not medical advice. This page is for general education and does not replace diagnosis or treatment by a licensed clinician. Do not start, stop, or change any medication, supplement, or treatment based on this content. Reference and optimal ranges vary between laboratories interpret your results with the range on your own report and a qualified professional.