Homocysteine Test
Reviewed
Also called: total homocysteine, plasma total homocysteine
A homocysteine test measures the amount of homocysteine in a sample of your blood. Homocysteine is an amino acid.
Specimen: blood
Why this test may be ordered
- To measure your vitamin B6, B12, and folic acid levels
- To help diagnose homocystinuria, a rare, genetic disease that prevents your body from making an enzyme that helps to break down homocysteine
- To better understand your risk for heart attack or stroke if you already have an increased risk
Preparation and collection
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.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
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.
Understanding results
Normally, your homocysteine levels are low. 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.
- High homocysteine: A high homocysteine level may be a sign that: You are not getting enough vitamin B12 or folic acid in your diet. You may have a higher risk of heart disease, stroke, or other blood vessel disorders. Limitation: If your homocysteine levels are high, it doesn't always mean you have a medical condition that needs treatment. Next step: If you have high homocysteine levels, your provider may suggest that you take vitamin supplements or make changes in the foods you eat.
- High homocysteine with other conditions: 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. Limitation: Homocysteine levels may get higher as you get older. Next step: If you have questions about your results, talk with your provider.
- High homocysteine levels do not always mean you have a medical condition that needs treatment.
- Results may be affected by your age, your sex, and smoking.
- Even though high levels of homocysteine can damage arteries, studies have shown that in most cases lowering homocysteine levels does not reduce the risk of heart attack or stroke.
What to do next
If you have high homocysteine levels, your provider may suggest that you take vitamin supplements or make changes in the foods you eat. If you have questions about your results, talk with your provider.
- What do my homocysteine test results mean for my health?
- Do I need any follow-up tests based on my homocysteine level?
- Should I make changes to my diet or take vitamin supplements?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.