Homocysteine Test
A homocysteine test measures the amount of homocysteine in a sample of your blood.
A homocysteine test measures the amount of homocysteine in a sample of your blood. Homocysteine is an amino acid. Amino acids are molecules that your body uses to make proteins. Normally, your homocysteine levels are low. That's because your body uses vitamin B12, vitamin B6 , and folic acid (also called folate or vitamin B9) to quickly break down homocysteine and change it into other substances that your body needs. High levels of homocysteine in your blood may be a sign that this process isn't working right or that you're lacking certain B vitamins. If homocysteine isn't broken down, it can build up in your arteries (blood vessels that carry oxygen-rich blood from your heart and lungs to your body). This can not only damage your arteries but also increase your risk of forming blood clots. An increased risk of forming blood clots may increase your risk for heart attack , stroke , and other heart diseases and blood vessel disorders . Other names: total homocysteine, plasma total homocysteine
Why is this test ordered? You may need this test if you are at high risk for low levels of vitamin B12 or folic acid or if you have symptoms that suggest you lack either of these vitamins. The symptoms may be very mild to severe and may include: Dizziness . Fatigue and/or weakness. Headache . Heart palpitations (racing or pounding heart). Changes in the color of your skin or fingernails. Sores on your tongue or in your mouth. Tingling or numbness in your hands, feet, arms, and/or legs. You may be at high risk for low levels of vitamin B12 or folic acid if you: Have malnutrition . Are an older adult. Older people often can't absorb enough vitamin B12 from food. Have alcohol use disorder or a drug addiction . Your provider may also recommend this test if you have: Had a heart attack or stroke. One or more conditions that increase your risk for heart attack or stroke, such as high LDL "bad" cholesterol or high blood pressure. Homocystinuria. Because this condition makes the breakdown of homocysteine difficult, you are more likely to have high levels of this amino acid.
Clinical Interpretation
A high homocysteine level may be a sign that: You are not getting enough vitamin B12 or folic acid in your diet. You (or your child) have homocystinuria. You will probably need more testing to rule out or confirm a diagnosis of homocystinuria. You may have a higher risk of heart disease, stroke, or other blood vessel disorders. Higher than normal homocysteine levels may also happen with other conditions, such as osteoporosis , chronic kidney disease , hypothyroidism , schizophrenia , or Alzheimer's disease or other types of dementia . If your homocysteine levels are high, it doesn't always mean you have a medical condition that needs treatment. Your results may be affected by: Your age. Homocysteine levels may get higher as you get older. Your sex. Males usually have higher homocysteine levels than females, but levels in females increase after menopause . Smoking . If you have questions about your results, talk with your provider. Learn more about laboratory tests, reference ranges, and understanding results .
Clinical Protocol & Patient Advice
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You may need to fast (not eat or drink) for 8-12 hours before a homocysteine test. Some medicines and supplements may affect your test results. So, tell your provider about all medicines and supplements you take, especially vitamin B. But don't stop taking any medicines unless your provider tells you to.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.