Bleeding Disorders Health Article

Definition

Bleeding disorders are disruptions in the body's ability to control blood clotting. Patients with these conditions bleed easily for longer periods of time than normal.

Description

Coagulation, or clotting, is a complex process involving at least 20 components of the blood, including various enzymes, messenger chemicals, and proteins. Under normal circumstances, the components necessary for coagulation circulate in the blood. When an injury occurs, they act together in a series of chain reactions to form a clot and prevent uncontrolled bleeding. Several disorders affect the blood's clotting components and diminish normal clotting capability. For people with these disorders, even a small injury could make them bleed to death.

Anatomy of a blood clot

In healthy individuals, clots begins when fibrin, an insoluble protein that forms the skeleton of the clot, forms at the wound site from fibrinogen, a soluble protein present in plasma. This chemical change is made possible by thrombin, an enzyme that itself is only created from the compound prothrombin when an injury occurs. Once fibrin strands are formed at the wound site, they trap platelets that flow past them. Platelets then initiate the contraction of damaged blood vessels so that less blood is lost. They also help plug damaged blood vessels and work with plasma to accelerate blood clotting.

Hemophilia A

Mild-to-moderate forms of hemophilia A may be controlled with desmopressin acetate, a synthetic form of a pituitary hormone that rapidly increases that amount of available factor VIII and von Willebrand factor. This drug is called DDAVP in the injectable form, and Stimate when formulated as a nasal spray. Severe bleeding episodes will require transfusions of human blood clotting factors. Many hemophiliacs, however, have become resistant to this form of treatment and have developed antibodies against it. For these patients, a synthetic protein called factor VIIa (tradename NovoSeven) can increase coagulation or prevent bleeding episodes altogether. Factor VIIa is made with recombinant DNA technology. Fetal tissue implants and gene therapies are also being studied as possible treatments for hemophilia.

Hemophilia B

The treatment for hemophilia B is similar to that for hemophilia A, with the infusion of synthetic and human blood products, such as factor IX concentrate or factor IX complex (prothrombin) concentrate, to promote coagulation.

Hemophilia C

Hemophilia C is most often treated with plasma, since concentrates of factor XI are not universally available in the United States, due to the disease's extreme rarity.

Disseminated intravascular coagulation disorder (DIC)

Unlike hemophilia, DIC, also known as consumption coagulopathy or defibrination syndrome, is neither hereditary nor common. It is almost always caused by another disease or condition, which in turn activates abnormal and uncontrolled clotting. This causes many small blood clots to form throughout the body, giving the disease its name. This overproduction of clots depletes the supply of clotting factors and platelets necessary to prevent hemorrhage when an injury (or surgery) occurs. Patients with DIC will bleed abnormally even though there is no history of coagulation disorder.

Thrombocytopenia (TCP)

Thrombocytopenia is a group of bleeding disorders characterized by severely diminished platelet counts, which cause internal bleeding. TCP can occur during pregnancy, as a reaction to certain medications, when the spleen and lymph produce antibodies against platelets, or for no known reason, a type called idiopathic TCP.

Other bleeding disorders

Von Willebrand's disease often requires no treatment because the bleeding is mild and controllable. DDAVP can help raise levels of the Von Willebrand factor and is the treatment of choice for many cases. However, if trauma or surgery is scheduled there are several methods that will reduce bleeding time and replace factor VIII, which will consequently replace the von Willebrand factor. This may include infusion of cryoprecipitate or plasma,. For severe bleeding, infusions of a viral inactivated factor VIII products such as Humane-P, Alphanate, and Koate DVI may be required.

Hypoprothrombinemia may be treated with concentrates of prothrombin. Acquired cases are often treated with vitamin. In bleeding episodes, the patient may receive plasma products.

Factor VII deficiency patients may be treated with normal plasma or concentrates containing factor VII or the biomedically engineered VIIa.