Bleeding Disorders

Bleeding disorders are a broad group of diseases that can be categorized under multiple different causes and clinical presentations. There are several different types of bleeding disorders that have several different etiologies. Most bleeding disorders are caused by defects in the body's normal blood clotting capability. Common causes of bleeding disorders are due to problems with normal functioning of platelets, clotting factors, blood vessels, and tissue integrity. Disorders involving certain aspects of the normal clot formation process can be due to an inherent disease process or genetic defect, they can be caused by adverse effects of certain medications, or they can be caused secondarily to other disease states. All these disorders share in common that an individual with this bleeding disorder will have an increased propensity to bleed as well as the inability to stop the bleeding and maintain normal homeostasis functioning.

Homeostasis is the body's capacity to maintain normal blood flow to essential organs and body parts through a series of blood vessels (i.e., arteries, capillaries, and veins) and supporting tissues. Homeostasis functions to maintain sufficient tissue perfusion by preventing excess formations of thromboses (clots inside blood vessels) as well as breaking up existing clots when required (disorders of this aspect of homeostasis are not going to be addressed in this entry, see Hypercoagulable Disorders). The body's homeostasis must also function to prevent the loss of blood by the ability to form clots when necessary. Defects in this component of homeostasis are the source of most bleeding disorders and will be addressed in this entry.

In cases of tissue damage in humans, the normal response of the body is to form clots to stop bleeding and initiate tissue repair. Blood clots are formed by the interaction of certain components of tissues, platelets, blood clotting factors and other blood signaling molecules. These compounds undergo various complex chemical interactions, thereby allowing the body to precisely regulate the extent of clotting at the exact site of injury. It is likely there will be some form of a bleeding disorder if the body has a defect in the functioning of the normal clotting system.