Doctors use blood tests to reveal important information about the health of a patient's heart and cardiovascular system. One of these tests monitors the level of homocysteine, an organic compound that the body produces and uses as a building block for proteins and body tissue. Elevated blood levels of homocysteine may put a patient at increased risk of stroke and heart disease.
Harmful Effects
Atherosclerosis is a form of heart disease that occurs when vital arteries become hardened and narrowed by the deposition of plaque, a fatty substance, on the arterial walls. Homocysteine at elevated blood levels may contribute to atherosclerosis by injuring the tissue lining the inner walls of the arteries. However, there is no clinical proof that elevated homocysteine causes atherosclerosis.
Causes of Elevated Homocysteine
Dietary and hereditary factors influence a patient's homocysteine blood level. Folic acid, or vitamin B-9, vitamin B-6 and vitamin B-12 play a part in clearing homocysteine from the blood. Therefore, a diet that does not include sufficient amounts of these vitamins contributes to higher blood levels of homocysteine. In addition, elevated homocysteine blood levels may arise from medical problems such as insufficient thyroid hormones, psoriasis and kidney disease, and from medications such as epilepsy treatments and methotrexate for arthritis.
Epidemiological Evidence
Epidemiological studies, examinations of population groups, have established an association between high blood levels of homocysteine and elevated risk of cardiovascular disease. For example, in an article in the September 2002 issue of "Stroke," researchers report that they studied a large group of Japanese men and women ages 40 to 94 and found that mild elevation in blood levels of homocysteine was a risk factor for an increased thickness in the wall of the carotid artery.
Considerations
Even though epidemiological studies suggest a link between high levels of homocysteine and the risk of cardiovascular problems, scientists still don't know if high homocysteine is the cause, according to Dr. Howard Hodis of the Atherosclerosis Research Unit at the University of Southern California. Randomized clinical trials are the way to determine whether high levels of homocysteine cause cardiovascular troubles. In the January-February 2007 issue of "British Columbia Medical Journal," researchers describe three clinical trials in which homocysteine blood levels of patients with cardiovascular disease were lowered by treatment with vitamin B-6, vitamin B-12 and folic acid. In all cases, lowering homocysteine blood levels did not lead to a reduction in cardiovascular problems. The researchers state that these clinical results suggest that homocysteine is not the cause of the cardiovascular troubles.
References
- MayoClinic.com: Heart Disease: Blood Tests for Heart Disease: Introduction: Homocysteine
- American Heart Association: Homocysteine, Folic Acid and Cardiovascular Disease
- HeartHealthyWomen.Org: Risk Factors: Homocysteine
- "Stroke"; Plasma Homocysteine Levels and Atherosclerosis in Japan: Epidemiological Study By Use of Ultrasonography; Hisashi Adachi, et al.; September 2002
- USC Health Magazine: The New Cholesterol
- "British Columbia Medical Journal"; Lack of Benefit in Treating High Homocysteine Levels With Vitamins; Jiri Frohlich, et al.; Jan.-Feb. 2007
