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Does this test have other names?

Total homocysteine (hoe-moe-SIST-een)

What is this test?

This test measures levels of homocysteine in your blood. Homocysteine is a type of amino acid your body naturally makes. At high levels, homocysteine can damage the lining of arteries and encourage blood clotting. As a result, high levels may raise your risk for coronary artery disease, heart attacks, blood clots, and strokes.

Having low levels of vitamin B-12 (cobalamin), vitamin B-6 (pyridoxine), vitamin B-2 (riboflavin), or vitamin B-9 (folic acid, folate) can cause high levels of homocysteine. Thyroid disease, kidney disease, psoriasis, and some medicines can also raise your homocysteine level. Certain genetic causes, such as homocystinuria, will also lead to high homocysteine levels.

Routine screening for homocysteine is not recommended because of the cost. The treatment that is recommended is taking a multivitamin. This has a low cost and is generally a safe treatment.

Why do I need this test?

You might have this test to find out whether you have coronary artery disease or are at higher risk for this problem. You may also have this test to check for low levels of vitamin B-12 or folate, which is another name for folic acid. In addition, you may be tested to see whether treatments for high homocysteine—such as nutritional changes, folic acid, or vitamin B supplements—are working to lower your homocysteine levels.

What other tests might I have along with this test?

Your levels of vitamin B-6, vitamin B-12, and folate may also be measured when you have a homocysteine test.

What do my test results mean?

A result for a lab test may be affected by many things, including the method the laboratory uses to do the test. If your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.

The normal range of homocysteine levels are less than 15 micromoles per liter (mcmol/L). Higher levels are:

  • Moderate (15 to 30 mcmol/L)

  • Intermediate (30 to 100 mcmol/L)

  • Severe (greater than 100 mcmol/L)

Higher levels could point to a B vitamin deficiency and a higher risk for coronary artery disease. 

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

What might affect my test results?

Taking B vitamin supplements can affect results of a homocysteine test.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, and a sense of lightheadedness. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

How do I get ready for this test?

No special steps are necessary to prepare for this test. 

Medical Reviewers:

  • Moloney Johns, Amanda, PA-C, MPAS, BBA
  • Snyder, Mandy, APRN