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Blood Protein May Trigger Unwanted Clots, Study Suggests

July 4, 1990

NEW YORK (AP) _ High levels of a blood protein may trigger potentially fatal clots in surgery patients, suggests a study that may give leads for prevention.

Mice born with excessive levels of the protein developed clots in their tails and hind feet, researchers said.

The study suggests that elevated amounts of the protein may promote a clotting disorder called deep venous thrombosis, said Laurence Erickson of The Upjohn Co. in Kalamazoo, Mich.

If further research proves that, measuring the level before surgery may indicate patients at high risk for the clotting disorder, targeting them for currently available preventive therapy, Erickson said. And researchers may someday find ways to reduce the risk of clotting by lowering a patient’s level of the protein, he said.

The protein is called plasminogen activator inhibitor-1, or PAI-1. It normally keeps the body from destroying clots prematurely.

Deep venous thrombosis is the formation of clots in veins, usually in the leg. The clots can kill if they break free and travel to the heart or lung.

The condition can appear after major surgery, in cancer patients and people who inherit a tendency toward them. Doctors treat it with anti-clotting drugs.

In all, perhaps 200,000 to 300,000 cases occur in the United States each year, with an estimated 20,000 or more deaths a year, said venous thrombosis researcher Dr. Philip Comp of the University of Oklahoma.

Comp said he believed it would be difficult to manipulate PAI-1 levels to prevent the clotting disorder. As for indicating patients at risk, he said high levels in the blood may signal conditions unrelated to the risk. Even if high levels were related, he said, only a small percentage of people deemed at risk would probably get clots anyway.

Erickson and Upjohn colleagues presented their results in Thursday’s issue of the British journal Nature.

The mice produced excessive levels of PAI-1 because they had been given an extra gene for it before birth. Clotting appeared shortly after birth, and disappeared later on after production of PAI-1 fell back to normal.

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