Test Details: Homocysteine test is used to measure the amount of homocysteine which is a amino acid that the body uses to make proteins. Normally vitamins, in our body, like B12, B6 and folic acid break down homocysteine and change it into other substances that our body requires. The high levels of homocysteine indicate that the body is deficient in vitamins B6, B9 (folate) or B12. This test may be used to monitor those who have heart diseases and have risk of a heart attack or stroke and for those who may develop Alzheimer's disease.