Overview of Blood Clotting Disorders

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

• Blood vessels

• 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

• Hemophilias

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)

• Disseminated intravascular coagulation

• Severe liver disease (including cirrhosis, hepatitis, acute liver failure, or acute fatty liver of pregnancy)

• Vitamin K deficiency