What Is Excessive Blood Clotting (Hypercoagulation)?

When you get a cut or wound, your body forms blood clots, a thickened mass of blood tissue, to help stop the bleeding. Proteins in your blood (fibrins) work with small blood cell fragments (platelets) to form the clot. This is called coagulation, or clotting, a process that helps the body form a clot when an injury occurs because it slows blood loss.

After bleeding has stopped and healing has occurred, the body should break down and remove the clots. But sometimes blood clots form too easily or don't dissolve properly and travel through the body limiting or blocking blood flow.

This is called excessive blood clotting or hypercoagulation and can be very dangerous. In a case of excessive blood clotting, these clots can form in, or travel to, the arteries or veins of any organ, which can cause heart attack, stroke, damage to the body’s organs or even death.

Many factors can cause excessive blood clotting including certain diseases and conditions, genetic mutations and medicines. These causes fall into two categories: acquired and genetic.

• Acquired means that excessive blood clotting was triggered by another disease or condition. Smoking, overweight and obesity, pregnancy, use of birth control pills or hormone replacement therapy, cancer, prolonged bed rest, or car and plane trips are a few examples.
• The genetic, or inherited, source of excessive blood clotting is less common and is usually due to genetic defects. These defects usually occur in the proteins needed for blood clotting and can also occur with the substances that delay or dissolve blood clots.

Acquired and genetic sources of excessive blood clotting are not related but a person can have both.

• Hypercoagulable disorders or states
• Hypercoagulation
• Thromboembolic states
• Thrombophilia (a name used mainly for genetic conditions)
• Thrombotic disorders

Why excessive blood clotting matters

The outlook and treatment for excessive blood clotting depend on the cause of the blood clots, how severe they are and how well they can be controlled.

• Stroke – A stroke can occur if a blood clot causes blood flow to your brain to be restricted. If blood flow is cut off for more than a few minutes, the cells in your brain start to die. This impairs the parts of the body that the brain cells control. A stroke can cause lasting brain damage, long-term disability, paralysis (an inability to move) or death.
• Heart attack – A blood clot in a coronary artery can lead to a heart attack. A heart attack occurs if blood flow to a section of heart muscle becomes blocked. If blood flow isn't restored quickly, the section of heart muscle becomes damaged from lack of oxygen and begins to die. This heart damage may not be obvious, or it may cause severe or long-lasting problems such as heart failure or arrhythmias.
• Pulmonary embolism – If a blood clot travels from a deep vein in the body to the lungs, it’s called a pulmonary embolism (PE). PE is a serious condition that can damage your lungs and other organs and cause low oxygen levels in your blood.
• Deep vein thrombosis – A blood clot in a vein deep in your leg or arm can cause pain, swelling, redness or increased warmth in the affected limb and can cause deep vein thrombosis (DVT). These clots can break off, travel to the lungs and cause PE.
• Venous thromboembolism (VTE) – Together, PE and DVT make up a venous thromboembolism.
• Peripheral artery disease (PAD) –  PAD is a narrowing of the peripheral arteries, most commonly in the arteries of the pelvis and legs.
• Pregnancy-related problems – Blood clots can cause miscarriages, stillbirths and other pregnancy-related problems, such as preeclampsia, which is high blood pressure that occurs during pregnancy.

• Kidney failure – A blood clot in the kidneys can lead to kidney failure, where kidneys can no longer remove fluids and waste from your body. 

With medicines and ongoing care, many people who have excessive blood clotting can successfully manage it.