URL of this page: https://medlineplus.gov/lab-tests/homocysteine-test/

Homocysteine Test

What is a homocysteine test?

A homocysteine test measures the amount of homocysteine in your blood. Homocysteine is a type of amino acid, a chemical your body uses to make proteins. Normally, vitamin B12, vitamin B6, and folic acid break down homocysteine and change it into other substances your body needs. There should be very little homocysteine left in the bloodstream. If you have high levels of homocysteine in your blood, it may be a sign of a vitamin deficiency, heart disease, or a rare inherited disorder.

Other names: total homocysteine, plasma total homocysteine

What is it used for?

A homocysteine test may be used to:

  • Find out if you have deficiency in vitamin B12, B6, or folic acid.
  • Help diagnose homocystinuria, a rare, inherited disorder that prevents the body from breaking down certain proteins. It can cause serious health problems and usually starts in early childhood. Most U.S. states require all infants to get a homocysteine blood test as part of routine newborn screening.
  • Screen for heart disease in people at high risk for heart attack or stroke
  • Monitor people who have heart disease.

Why do I need a homocysteine test?

You may need this test if you have symptoms of a vitamin B or folic acid deficiency. These include:

  • Dizziness
  • Weakness
  • Fatigue
  • Pale skin
  • Sore tongue and mouth
  • Tingling in the hands, feet, arms, and/or legs (in vitamin B12 deficiency)

You may also need this test if you are at high risk for heart disease because of prior heart problems or a family history of heart disease. Excess levels of homocysteine can build up in the arteries, which may increase your risk of blood clots, heart attack, and stroke.

What happens during a homocysteine test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You may need to fast (not eat or drink) for 8–12 hours before a homocysteine test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

If your results show high homocysteine levels, it may mean:

  • You are not getting enough vitamin B12, B6, or folic acid in your diet.
  • You are at a higher risk of heart disease.
  • Homocystinuria. If high levels of homocysteine are found, more testing will be needed to rule out or confirm a diagnosis.

If your homocysteine levels were not normal, it doesn't necessarily mean you have a medical condition needing treatment. Other factors can affect your results, including:

  • Your age. Homocysteine levels can get higher as you get older.
  • Your gender. Men usually have higher homocysteine levels than women.
  • Alcohol use
  • Smoking
  • Use of vitamin B supplements

If you have questions about your results, talk to your health care provider.

Is there anything else I need to know about a homocysteine blood test?

If your health care provider thinks a vitamin deficiency is the reason for your high homocysteine levels, he or she may recommend dietary changes to address the problem. Eating a balanced diet should ensure you get the right amount of vitamins.

If your health care provider thinks your homocysteine levels put you at risk for heart disease, he or she will monitor your condition and may order more tests.

References

  1. Allina Health [Internet]. Minneapolis: Allina Health; c2018. Plasma homocysteine measurement [updated 2016 Mar 29; cited 2018 Apr 1]; [about 3 screens]. Available from: https://www.allinahealth.org/CCS/doc/Thomson%20Consumer%20Lab%20Database/49/150198.htm
  2. American Heart Association [Internet]. Dallas: American Heart Association Inc.; c2018. Heart and Stroke Encyclopedia [cited 2018 Apr 1]; [about 3 screens]. Available from: http://www.heart.org/HEARTORG/Encyclopedia/Heart-and-Stroke-Encyclopedia_UCM_445084_ContentIndex.jsp?levelSelected=6
  3. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2018. Homocysteine [updated 2018 Mar 31; cited 2018 Apr 1]; [about 3 screens]. Available from: https://labtestsonline.org/tests/homocysteine
  4. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2018. Coronary artery disease: Symptoms and Causes; 2017 Dec 28 [cited 2018 Apr 1]; [about 3 screens]. Available from: https://www.mayoclinic.org/diseases-conditions/coronary-artery-disease/symptoms-causes/syc-20350613
  5. Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2018. Test ID: HCYSS: Homocysteine, Total, Serum: Clinical and Interpretative [cited 2018 Apr 1]; [about 4 screens]. Available from: https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/35836
  6. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2018. Homocystinuria [cited 2018 Apr 1]; [about 2 screens]. Available from: https://www.merckmanuals.com/home/children-s-health-issues/hereditary-metabolic-disorders/homocystinuria
  7. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests [cited 2018 Apr 1]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
  8. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2018. Health Encyclopedia: Homocysteine [cited 2018 Apr 1]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID;=homocysteine
  9. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Homocysteine: Results [updated 2017 Oct 9; cited 2018 Apr 1]; [about 8 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/homocysteine/tu2008.html#tu2018
  10. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Homocysteine: Test Overview [updated 2017 Oct 9; cited 2018 Apr 1]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/homocysteine/tu2008.html
  11. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Homocysteine: What To Think About [updated 2017 Oct 9; cited 2018 Apr 1]; [about 10 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/homocysteine/tu2008.html#tu2020
  12. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Homocysteine: Why It is Done [updated 2017 Oct 9; cited 2018 Apr 1]; [about 3 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/homocysteine/tu2008.html#tu2013

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.