Dr. Shapiro Answers Your Clotting Questions

What is thrombophilia?

Thrombophilia or a clotting disorder is a term used to describe a group of conditions in which there is an increased tendency for excessive clotting. People with a clotting disorder often have repeated clotting events over an extended period.

Clotting conditions may be due to:

  • A family history of clotting or a diagnosis based on a demonstrated genetic mutation such as Factor V Leiden, protein C and S deficiencies, antithrombin deficiency, and prothrombin 20210A mutations

  • An acquired condition, such as a lupus anticoagulant or antiphospholipid antibody syndrome, which can occur as a manifestation of an autoimmune disorder, or as part of a syndrome such as systemic lupus erythematosus.

The development of a blood clot is called thrombosis. The vascular system includes both the venous system (the veins that deliver blood from the tissues to the heart) and the arterial system (the system that delivers blood from the heart to the tissues).

Thrombotic episodes may occur in either system. The symptoms that occur with a thrombosis relate to the part of the vascular system in which they occur, the extent of the clot, and whether the clot breaks off and travels to another part of the body, e.g., the lungs (pulmonary embolism) or the brain (embolic stroke).

There are different terms used to define further these thrombotic episodes, such as deep vein thrombosis or peripheral vascular disease, which refers to clots in the arterial system, commonly in the extremities. Although we are now able to determine the underlying cause in some patients and families for this tendency towards excessive blood clotting, we are not yet able to identify the cause in all cases. This means that there is still more to be understood about why some persons and families develop thromboses or have thrombophilia.

Is thrombophilia a new disease?

Thrombophilia is not a new disease, but it has become better recognized and is a more frequently discussed topic due to an increased ability to test for and identify some of the underlying contributing factors.

Who has thrombophilia?

Thrombophilia affects a large number of people in the world. People who experience episodes of thrombosis, either as an isolated event or as a repeated event, may be affected by an underlying thrombophilic disorder.

Some individuals have an inherited condition, such as factor V Leiden or activated protein C resistance, that leads to an increased tendency for thrombosis, but they may never experience a blood clot. (This means that they have a known thrombophilic condition but may never experience a thrombosis).

Both children and adults may have thrombophilia, but it is more commonly diagnosed during adolescence or as an adult due to normal changes that occur with growth and aging. Both men and women may have thrombophilia. In fact, women who have thrombophilia may have an increased tendency to express symptoms due to the contributing effects of pregnancy or use of hormonal agents (including oral contraceptives).

How many people in the United States have thrombophilia?

Thrombosis is a very common medical problem. It is estimated that up to 1 million people experience a deep vein thrombosis each year in the United States. In addition, nearly half of patients with deep vein thrombosis experience long-term health consequences that adversely affect their quality of life and require expensive treatment.

Thrombosis may manifest itself as the formation or presence of a blood clot in a blood vessel or in one of the chambers of the heart. In fact, emboli (clots that break off and are brought by the blood into a smaller vessel where they may obstruct the circulation) from a deep vein thrombosis are a leading cause of death in hospitalized patients.

Approximately 30% of people who have had a deep vein thrombosis are at risk for another episode. Nearly 40% of patients with deep vein thrombosis experience a pulmonary embolism (a clot that travels to the lung and obstructs blood flow to the pulmonary tissue that can impair function). Pulmonary emboli are fatal in 30% of cases.

Recent research shows that these disorders significantly contribute to morbidity and mortality in the United States. Each year, more than 600,000 Americans die from abnormal blood clots.

Factor V Leiden is the most common inherited abnormality that leads to an increased tendency for thrombosis. Factor V Leiden affects approximately 5–10% of the white population of European descent in the United States. Many of these individuals have never experienced a thrombotic event.

What are the differences between genetic and acquired forms of thrombophilia?

Genetic thrombophilia is an inherited condition that leads to an increased risk of thrombosis throughout a person’s life. The most common inherited thrombophilic disorder is Factor V Leiden, initially described by Bjorn Dahlbäck in 1993.

Acquired thrombophilia refers to a group of disorders that an individual is not born with, but may develop throughout his or her life due to another illness or situation. An example of acquired thrombophilia is the development of a lupus anticoagulant or antiphospholipid antibody syndrome.

Who takes care of patients with thrombophilia?

Many healthcare professionals care for individuals affected by thrombophilia. For example, primary healthcare providers (pediatricians, internal medicine physicians, family practitioners, obstetricians and gynecologists, emergency physicians) may all care for patients with thrombophilia.

Subspecialists, such as pulmonologists, vascular surgeons, neurologists, and hematologists, may also care for this patient population. Other specialists, such as pathologists and radiologists may provide services to these patients, such as diagnostic and interventional care. There is an increasing tendency for affected individuals to be referred to a facility or physician that provides expertise in clotting disorders.

How is thrombophilia related to hemophilia?

While people with hemophilia have an increased tendency to bleed, people with thrombophilia have an increased tendency to clot. Just as hemophilia is caused by an abnormality of a blood-clotting factor, some forms of thrombophilia are also caused by an abnormality of a blood-clotting factor.

In some cases, these clotting factors may have an abnormality that leads to an increase in their function (such as Factor V Leiden or the prothrombin 20210 mutation), whereas in other circumstances it is due to decreased function that does not allow active clotting to be down-regulated (protein C or S deficiency and antithrombin 3 deficiency).

Thrombophilia is also related to hemophilia in that the providers that staff hemophilia treatment centers (HTCs) are well suited to provide the needed specialized services to this population. Thrombophilic disorders are not uncommon; in fact, a person with hemophilia may also inherit a thrombophilic abnormality. Some studies suggest that individuals with hemophilia who also inherit Factor V Leiden begin bleeding at a later age and may bleed less frequently.

What kinds of treatment do people with thrombophilia need?

People with thrombophilia may require medications that affect the coagulation system. Some people with thrombophilia may receive replacement factor concentrate to treat their thrombophilia either on a long-term or an intermittent basis, depending on their underlying condition.

Some people with thrombophilia are treated with medications that are classified as blood thinners, medications that decrease a person’s ability to form a clot. Examples of these medications include aspirin, heparin, low molecular weight heparin and warfarin.

There are also some medications (thrombolytic agents) that are given under specific circumstances to dissolve clots. People with hemophilia who have central venous access devices that have become obstructed by a clot may receive small doses of these medications through the device.

People with thrombosis may receive these agents in larger doses either administered directly at the site of thrombosis or throughout their entire body (systemically). People with thrombophilia may receive medications during a time of increased risk for development of thrombosis (preventative therapy); for a prolonged period; or even for their lifetime, depending on their specific diagnosis and clinical circumstances.

Is there a patient organization that advocates for improved treatment and more research related to thrombophilia?

Yes, there is a national community-based volunteer health organization called the National Blood Clot Alliance, which is committed to prevention and treatment of the many important health problems related to blood clots.

How many hemophilia treatment centers care for thrombophilia patients?

Many hemophilia treatment centers provide care to people with clotting disorders. The demand for hematologic expertise from HTC providers is growing at a rapid rate. Hemophilia treatment centers have access to physical therapists, nutritionists, social workers, and sometimes anticoagulation clinics and specialized pharmacy programs that can provide expert services to this population.

(This interview is adapted from an article that first appeared in the September/October 2001 issue of HemAware magazine [Volume 6, Issue 5], published by the National Hemophilia Foundation. Reprinted with permission.)