Homocysteine · high result
What does a high Homocysteine mean?
Short answer
High homocysteine most often reflects low folate, B12 or B6, kidney disease, hypothyroidism, smoking, heavy coffee or alcohol intake, or medications (methotrexate, metformin, some anticonvulsants); MTHFR gene variants contribute modestly. It is associated with cardiovascular and clot risk and, at very high levels, with neurological effects, though lowering it with vitamins has not clearly reduced heart attacks. Checking and correcting the B vitamins is the practical step.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for Homocysteine?
- age 18+: 4.00 – 10.0 umol/L
Often reflects B12, folate, or B6 deficiency, kidney disease, or genetic factors. May increase cardiovascular risk.
Full reference table, citations and testing options: Homocysteine biomarker page.
What are the common causes of high Homocysteine?
- Folate, vitamin B12 or B6 deficiency
- Chronic kidney disease
- Hypothyroidism
- MTHFR variants (mild effect), rare homocystinuria (very high)
- Medications: methotrexate, metformin, phenytoin, carbamazepine, nitrous oxide exposure
- Smoking, heavy alcohol or coffee, sedentary lifestyle
What symptoms go with high Homocysteine?
- None from homocysteine itself
What do clinicians usually check next?
- Folate, vitamin B12 (with methylmalonic acid) and B6
- Kidney function and TSH
- Repeat 8–12 weeks after correcting deficiencies
Follow-up tests available at TestWell: TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99), Vitamin B12 ($25.99), Methylmalonic Acid (MMA) ($49.99), Folate (Vitamin B9) ($32.99).
How do you recheck Homocysteine?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Comprehensive B12 Deficiency Panel | Panel · 3 tests | $79.99 | Yes | 5–12 business days |
| Inflammation Panel | Panel · 7 tests | $119.99 | Yes | 2–5 business days |
| Longevity & Anti-Aging Panel | Panel · 13 tests | $239.99 | Yes | 3–7 business days |
| Homocysteine | Test | $27.99 | Yes | 2–5 business days |
Common questions
Should I take methylfolate for high homocysteine?
First find out whether folate, B12 or B6 is actually low, and whether kidney or thyroid function explains it. Replacing a documented deficiency lowers homocysteine; broad supplementation without a deficiency hasn't shown cardiovascular benefit.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.