Elevated levels of fibrinogen, a protein synthesized by the liver which is necessary for normal blood clotting, increases the risk for cardiovascular disease (CVD) and may be the mechanism by which many recognized cardiac risk factors cause disease.

Researchers evaluated fibrinogen levels in participants of the Framingham Offspring Study, a long-term, ongoing study that has been investigating CVD risk factors since 1948.

Of 2,632 study subjects with available fibrinogen measurements, 267 had known cardiovascular disease.

Investigators evaluated the association between fibrinogen and traditional risk factors of CVD, including total and HDL cholesterol, diabetes, age, and cigarette smoking.

They also compared two different methods of measuring fibrinogen levels.

One test was the newly developed "functional intact fibrinogen" (FiF) test and the other was the older Clauss assay, in which fibrinogen is converted to fibrin, then timed to determine how long it takes a clot to form.

Patients with the highest levels of fibrinogen had a threefold greater risk of CVD than those with the lowest levels.

However, after adjusting for various risk factors, such as age, body mass index, smoking, diabetes, total cholesterol, and triglycerides, only elevated fibrinogen levels measured with the FiF test was found to be significantly associated with established CVD.

Fibrinogen is a good variable that is independently related to other CVD risk factors, lead author Ralph B. D'Agostino told WebMD.

Dr. D'Agostino also emphasized that although there are limited method that can be used to try to lower fibrinogen levels, behavioral and lifestyle changes, such as quitting smoking, losing weight and becoming more physically active may help.

The study was supported by grants from the National Institutes of Health and American Biogenetic Sciences, developer of the functional intact fibrinogen test.

Circulation: Journal of the American Heart Association October 3, 2000; 102: 1634