What Is Homocysteine
Homocysteine is an amino acid your body produces when it metabolizes an amino acid called methionine, which is found in protein-containing foods. Vitamins including vitamin B12, vitamin B6, and folate break down homocysteine into other substances, but when levels of these nutrients are low, or when certain genetic conditions interfere with metabolism, homocysteine can build up in your blood.
Over time, high levels of homocysteine can damage blood vessels, increasing the risk of atherosclerosis and blood clots. This increases the risk of heart attack and stroke.1
Why Does Homocysteine Matter?
- Can help identify vitamin deficiencies. Homocysteine rises when your body doesn’t have enough folate, vitamin B12, or vitamin B6 to metabolize it normally.
- Is an additional cardiovascular risk marker. High homocysteine is associated with increased cardiovascular risk independent of many traditional factors. disease, it doesn’t diagnose heart disease on its own.
- Helps identify stroke risk. Research links higher homocysteine with ischemic and other forms of stroke.
Who should get a homocysteine test?
Your physician may consider testing for high homocysteine levels if you have:
- Signs or risk factors for folate or vitamin B12 deficiency, such as unexplained fatigue, weakness, mouth sores, heart palpitations, or numbness and tingling in the hands or feet.
- Unexplained anemia, fatigue, weakness, or numbness and tingling that could indicate a B-vitamin deficiency
- Risk factors for cardiovascular disease or stroke, and your physician wants more information beyond standard cholesterol, blood pressure, and glucose testing.
- A medication or medical condition known to interfere with folate, B12, or B6 metabolism
- Personal or family history of premature cardiovascular disease
- Known MTHFR mutation
Book your test now
Test 50+ biomarkers & meet with a longevity physician, uncover the root cause of symptoms
- HSA/FSA eligible
- Physician reviewed
- 100% satisfaction guaranteed
How to Interpret Homocysteine Levels
(Ranges may vary slightly by lab)
Standard reference ranges represent the middle 95% of healthy individuals but don’t necessarily reflect levels associated with longevity. Optimal ranges are derived from clinical guidelines, peer-reviewed research, and real-world outcomes data, with an emphasis on levels associated with peak functioning and reduced disease risk.
Benefits of Optimizing Homocysteine
- Lower risk of heart attack and stroke
- Reduced risk of chronic kidney disease
- Effective processing of vitamins including B12, B6, and folate
Know your numbers. Own your health.
50+ biomarkers that reflect how your body is functioning — and where there’s room to optimize. Plus a clinical consult and personalized treatment plan. All for $65.
Low Homocysteine Levels
Low homocysteine levels are generally not a clinical concern.
High Homocysteine Levels
High homocysteine levels indicate that your body is producing the amino acid faster than it can recycle or break it down.
Symptoms:
High homocysteine levels usually don’t cause noticeable symptoms. Symptoms are more likely to come from the condition causing the elevation. For example, vitamin B12 or folate deficiency may cause:
- Fatigue or weakness
- Dizziness or headaches
- Heart palpitations
- Numbness or tingling in the hands or feet
- Memory problems
- Difficulty concentrating
Causes:
- Inadequate intake of folate, vitamin B12, B2 or vitamin B6
- Kidney disease
- Hypothyroidism
- Smoking
- Age-related changes
- Certain medications (e.g., methotrexate/antifolates, antiepileptics)
- Excess alcohol intake
- Chronic inflammatory diseases
- MTHFR gene variants that modestly reduce the ability to process folate
Healthspan Impacts:
- Greater cardiovascular risk
- Higher ischemic stroke risk
- Nutrient deficiencies
- Possible association with cognitive decline and dementia
- Pregnancy complications in susceptible individuals
How Hone Treats Out of Range Homocysteine Levels
Your Hone physician interprets homocysteine results from a blood test alongside blood count, kidney function, thyroid markers, cardiovascular biomarkers and your medical history to understand why the level is elevated. High homocysteine usually points to a B-vitamin shortage but is it also linked to a higher heart disease risk. Lowering high homocysteine with B-vitamins doesn’t reliably reduce heart attacks or strokes, so heart disease must be treated separately — physicians weigh homocysteine alongside cholesterol, ApoB, hs-CRP, blood pressure, glucose, kidney function, and lifestyle to get the full picture.
Hurjui LL, et al. (2025). Homocysteine Attack on Vascular Endothelium—Old and New Features
↑
Reviewed for Accuracy by Our Medical Review Board
This biomarker information has been reviewed by a member of Hone’s medical review board. As part of the medical review team, physicians fact-check this content against the latest research and their own experience treating their patients.
Ashley Winter, M.D., is a board-certified urogynecologist trained at Weill Cornell and Cleveland Clinic. She specializes in female and male sexual dysfunction, urinary issues, genital pain, and hormone therapy.
James Staheli, D.O., is the Medical Director for Broad Health, Hone Health’s affiliated medical practice and a family medicine doctor in Atlanta, Georgia.
