Homocysteine is now beginning to be used to help in the investigation of people who might be at high risk for heart attack or stroke. For example, it may be useful in patients who have a family history of coronary heart disease (CHD) but no other known risk factors.

The role of homocysteine for this purpose is however controversial because the role, if any, that it plays in the progression of CHD has not been established. There are, as of yet, no established guidelines for homocysteine testing, and routine screening is not recommended.
A doctor may also request a homocysteine test to determine if you have vitamin B12 or folate deficiency.

Homocysteine may be requested as part of a cardiac risk assessment, depending on your age and other risk factors. It may also be used following a heart attack or stroke to help determine treatment.

Recent studies have suggested that people who have raised homocysteine levels have a much greater risk of heart attack or stroke than those with average levels. Blockage of a coronary artery, an event that can lead to a heart attack, occurs with more than double the average frequency in people with homocysteine levels in the highest 25% as compared to those in the lowest 25%. This evidence suggests that measurement of homocysteine may be an even better indicator of who is at risk of having a heart attack or stroke than other tests, such as cholesterol and the lipid profile.

At present, a direct correlation between homocysteine levels and heart attacks has not been established, but there does seem to be strong evidence of a relationship between homocysteine levels and heart attack/stroke survival rates.

Since measuring homocysteine levels to determine cardiac risk is a relatively new use for the test, the exact reference range has yet to be determined.

NOTE: A standard reference range is not usually available on this site for tests. Because reference values are dependent on many factors, including patient age, gender, sample population, and test method, numeric test results have different meanings in different laboratories. Your laboratory report should include the specific reference range for your test. Lab Tests Online AU strongly recommends that you discuss your test results with your doctor. For more information on reference ranges, please read Reference ranges and what they mean.

There is a hereditary (genetic) form of homocystinuria – an increase of homocysteine in the urine – that causes a form of mental retardation, skeletal abnormalities, and premature cardiovascular disease. A gene mutation prevents an enzyme from breaking down homocysteine into products that can be excreted through the kidneys. The build-up of homocysteine thus becomes toxic to the body. The most common hereditary form results in both an increase in homocysteine and a decrease in folic acid.