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MTHFR test: who needs it and what the results mean

An MTHFR test is a genetic test that looks for two common changes in the MTHFR gene, C677T and A1298C, and most medical experts do not recommend it as a routine test. The CDC, the American College of Medical Genetics and Genomics and other groups say the result rarely changes care.

If the worry is high homocysteine, a homocysteine blood test is usually the better first step. Your homocysteine level, not your MTHFR genotype, guides what a clinician recommends.

Updated · Facts checked against the sources listed below

What the MTHFR test checks

The MTHFR gene makes an enzyme that helps your body use folate to turn homocysteine into methionine. The test checks a blood sample for the two most studied variants, C677T and A1298C. It can be ordered alone or as part of a larger genetic panel.

These variants are very common. The CDC says more people in the United States have one or two copies of C677T than have none. Having a variant is normal and, on its own, does not mean you have a health problem. Read more in MTHFR mutation.

Who should get an MTHFR test

Routine testing is not recommended for most people. A 2023 review in the Cleveland Clinic Journal of Medicine found that large studies do not support a link between the common variants and higher blood clot risk, and it advises against basing any workup or treatment on a common variant. MedlinePlus lists the narrow cases where a clinician may still order it:

  • Your homocysteine is high and a close relative has an MTHFR variant.
  • Your homocysteine is high and you or close family members had early heart or blood vessel disease.
  • You are starting methotrexate, where the result may help set a safe dose.
  • A newborn screen is positive for homocystinuria, a rare inherited condition.

Several groups advise against MTHFR testing as part of a blood clot workup or for recurrent pregnancy loss. Cleveland Clinic Laboratories stopped offering MTHFR genotyping and recommends a homocysteine test instead, because it is less expensive, faster and is what decides management.

What MTHFR test results mean

  • No variant found: neither common change was found. If your homocysteine is high, another cause is more likely, such as low B vitamins, certain medicines, older age, an underactive thyroid or kidney disease.
  • One copy (heterozygous): one changed copy alone is unlikely to cause health problems.
  • Two copies of C677T, or one copy each of C677T and A1298C: if your homocysteine is high, this probably helps explain it.
  • Two copies of A1298C: this probably does not explain a high homocysteine.

Treatment for high homocysteine is the same whether or not you carry a variant: usually B vitamins, chosen by your clinician. If homocysteine is normal, no treatment is needed for the variant itself. Anyone who could become pregnant should still take folic acid, even with an MTHFR variant; see folic acid vs methylfolate.

MTHFR test cost and insurance coverage

Many health plans do not cover MTHFR testing. For example, University of Utah Health Plans' 2025 policy calls it investigational and not medically necessary for all indications. Before you test, call your insurer and ask whether it covers MTHFR genotyping for your reason, and whether it needs prior authorization.

Self-pay prices vary by lab and by whether MTHFR is sold alone or inside a panel. MedlinePlus puts genetic tests in general anywhere from under $100 to more than $2,000. Ask the lab for its cash price before you order. For more, see does insurance cover genetic testing.

If you already have an MTHFR result from a consumer DNA kit or a past panel, you can upload it to Gabriel free and get a plain-language explanation.

Common questions

Should I get tested for MTHFR?

Most people don't need to. Experts advise against routine testing because the result rarely changes care. If you're concerned about high homocysteine, ask for a homocysteine blood test first.

Is the MTHFR test a blood test?

The clinical test MedlinePlus describes uses a blood sample from a vein in your arm, and no special preparation is needed.

Does insurance cover MTHFR testing?

Often not. Many plans list it as investigational or not medically necessary. Call your insurer before testing and ask about coverage and prior authorization.

What does it mean to be heterozygous for MTHFR?

It means you have one changed copy of the gene and one typical copy. One copy alone is unlikely to cause health problems.

If I have an MTHFR variant, should I avoid folic acid?

No. The CDC says people with an MTHFR variant can process folic acid, and anyone who could become pregnant should take 400 mcg a day even with a variant.

Sources

  1. MTHFR Gene Test MedlinePlus, U.S. National Library of Medicine
  2. MTHFR Gene Variant and Folic Acid Facts Centers for Disease Control and Prevention
  3. Is the MTHFR gene mutation associated with thrombosis? (Dhawan and Eng, 2023) Cleveland Clinic Journal of Medicine
  4. Best Practice for Detecting Hyperhomocysteinemia: Homocysteine Testing, Not MTHFR Genotyping Cleveland Clinic Laboratories
  5. Medical Policy MP-020: MTHFR Mutation Testing University of Utah Health Plans
  6. What is the cost of genetic testing, and how long does it take to get the results? MedlinePlus Genetics, U.S. National Library of Medicine

This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.