For example, 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 in a long car or plane ride, or if they suffer from certain heart conditions which cause blood to pool inside the heart. The blood clots can 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 its blood vessels, such as it 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 and others, 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
- Blood Counts
- Prothrombin Time
- Partial Thomboplastin Time
- Proteins C and S deficiency
- Antithrombin III mutations
- Lupus Anticoagulant
- Anticardiolipin antibody and the antiphospholipid syndrome.
J. P. Mohr, Dennis W. Choi, James C. Grotta, Bryce Weir, Phillip A. Wolf Stroke: Pathophysiology, Diagnosis, and Management Churchill Livingstone; 4th edition (2004)