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Blood Clotting Disorders and Stroke


Updated October 11, 2013

Leg blood clots can travel to the brain and cause a stroke
Photo © A.D.A.M.

Coagulation disorders are medical conditions in which blood clot formation is abnormal, causing people to develop a tendency to clot too much, or too little. Either of these blood clotting disorders can increase a person's risk of stroke.

When blood clotting is normal, platelets stick together to form a sort of plug at the point of injury, so that too much blood doesn't escape. The inability to form clots can result in excessive bleeding, while too much clotting can result in heart attack or stroke.

But when people tend to clot too much, they form blood clots inappropriately even if they are not bleeding. Blood clots can form in their legs when they sit for long periods of time, such as during a long car or plane ride. Certain heart conditions can also cause blood to pool inside the heart. In addition, blood clots can also find their way into the brain and cause an embolic stroke.

Blood clots can also form inside the brain itself, especially if there is inflammation in the brain's blood vessels, as happens with autoimmune diseases like lupus.

But sometimes the opposite occurs and people cannot form blood clots even when the body needs them to stop bleeding. This can happen due to genetic diseases such as hemophilia, or simply due to the use of blood thinners. Such a disorder puts people at risk of hemorrhagic stroke.

Common blood tests used to look for a blood clotting disorder

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