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Blood Molecule Increases Risk of Heart Attacks, Strokes | |
| BY DR. MICHAEL L. FREEDMAN New York University Medical Center For AP Special Features A once-obscure molecule called homocysteine has turned out to be a significant risk factor for heart disease and stroke for a significant number of people. Homocysteine, found in the blood, is a breakdown product of dietary methionine. Over the past decade, a number of studies have shown that high blood levels of homocysteine are associated with a high incidence of heart attack and stroke. Most people with homocystinuria - high blood levels of homocysteine - have it because they are deficient in one of three vitamins - vitamin B-12, vitamin B-6 or folic acid, which are needed to metabolize homocysteine. There are a few hereditary forms of homocystinuria. These disorders are caused by the deficiency or absence of enzymes necessary for metabolism of homocysteine and methionine. People with these genetic disorders have an increased likelihood of strokes and heart attacks in the second or third decade of life. High blood homocysteine also helps to explain the elevated incidence of cardiovascular disease in people who have kidney failure, which interferes with the metabolism of the molecule. Homocysteine causes cardiovascular disease because it causes platelets to become more sticky. These sticky platelets adhere to the lining of blood vessels leading to blockages. High blood homocysteine is a common condition among the elderly, largely because of a high incidence of vitamin B-12 deficiency. Perhaps one of every 12 older people is somewhat B-12 deficient. The most common reason is that many older people lack enough stomach acid, which is needed to split vitamin B-12 from food. Vitamin B-6 and folic acid deficiency can occur in the elderly. These people can be treated effectively with vitamin supplements, once the condition is identified. But widespread screening for high blood homocysteine is not routinely done. The test to detect it is expensive, ranging up to $122, and the cost-effectiveness of screening has not been proven. People who have hereditary homocystinuria often require treatment with appropriate doses of vitamin B-6. --- Dr. Michael L. Freedman is the Diane and Arthur Belfer Professor of Geriatric Medicine and Director of Geriatrics at New York University Medical Center. Copyright 1996 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | |