Blood clots help stop bleeding. Blood clotting (coagulation) disorders are dysfunctions in the body's ability to control the formation of blood clots. These dysfunctions may result in
Too little clotting, leading to abnormal bleeding (hemorrhage)
Too much clotting, leading to the development of excessive blood clots (thrombosis)
Abnormal bleeding means that people bruise and bleed too easily (see also Bruising and Bleeding and How Blood Clots). Abnormal bleeding can result from disorders of
Blood clotting (coagulation) system
Platelets (cell-like particles that help in the clotting system)
Clotting disorders occur when the body is unable to make sufficient amounts of the proteins that are needed to help the blood clot, stopping bleeding. These proteins are called clotting factors (coagulation factors). All clotting factors are made in the liver. The liver requires vitamin K to make some of the clotting factors.
Sometimes there is an abnormality of blood coagulation that increases the risk of clotting (called thrombophilia).
Disorders of coagulation can be
Hereditary
The result of some other disorder
Disorders of coagulation also occasionally develop on their own (spontaneously).
The most common hereditary coagulation disorders are
The primary causes of coagulation disorders that develop as a result of another disorder are
Development of circulating anticoagulants (antibodies that decrease the activity of a specific clotting factor)
Severe liver disease (including cirrhosis, hepatitis, acute liver failure, or acute fatty liver of pregnancy)
Tests of Blood Clotting
One commonly tested measure that affects the body's ability to stop bleeding is the count of the number of platelets. Less often, doctors test how well the platelets function.
Other tests can measure the overall, coordinated function of the many proteins needed for normal blood clotting (clotting factors). The most common of these tests are the prothrombin time (PT) and the partial thromboplastin time (PTT).
The levels of individual clotting factors can also be determined.
