Facts

Haemostasis

What is haemostasis?
Haemostasis is the human body's response to blood vessel injury and bleeding. It involves a series of interactions between platelets and numerous blood clotting proteins (or factors), resulting in the formation of a blood clot.

Tissue factor is a protein that comes into contact with blood once a blood vessel is injured. The process of haemostasis starts when tissue factor binds to a coagulation protein called activated factor seven (FVIIa). The binding of tissue factor and FVIIa is only the first step in a process that will eventually lead to the development of a strong, stable blood clot that will stop and prevent further bleeding.

Generally, in healthy people control of bleeding is achieved very quickly and without the need for medical intervention. In major trauma or surgery, physicians often need to help patients to achieve adequate haemostasis – in order to minimize blood loss and related injury.

However, some people are born with a bleeding disorder (congenital) that impairs their ability to achieve haemostasis. Most of these bleeding disorders are hereditary, or run in families. An example of this is congenital haemophilia.

In addition, some people who have never had any bleeding problems can develop a condition that causes them to bleed, known as acquired haemophilia. In this disorder, even minor cuts and bruises can require medical intervention.
Haemophilia imposes a heavy medical and economic burden on individual patients and society in general.

Haemophilia

What is congenital haemophilia?
Haemophilia is an inherited (congenital) bleeding disorder that occurs frequently in males. It occurs when the levels of certain clotting factors (factors VIII or IX) are reduced or are completely absent. This is because the gene that controls the production of the clotting factor does not work properly. In the case of haemophilia A, there is a problem with factor VIII and in haemophilia B it is factor IX. These clotting factors are essential in order to prevent uncontrolled bleeding. Without these clotting factors, bleeding will continue until treatment is given because the body is not able to produce sufficient natural clotting factors to form a clot to stop it.

What are inhibitors?
The normal treatment for haemophilia is to replace the missing clotting factor. However, some people’s immune systems respond to these replacement factors by developing antibodies known as inhibitors that destroy the clotting factor.

What is acquired haemophilia?
Acquired haemophilia is not inherited, and cannot be passed on in the family. It may develop suddenly when a person’s immune system starts to destroy his/ her own clotting factors by mistake. This reduction in the amount of clotting factor prevents the blood from clotting naturally, so bleeding continues

Who gets acquired haemophilia?
Acquired haemophilia is very rare, occurring in about 1-4 per million people every year. Men and women are equally likely to be affected. It is usually seen in older people, but has been associated with a wide variety of conditions, such as rheumatoid arthritis, pregnancy and as a reaction to certain drugs.