clotting disorders review ch.18

What are clotting disorders?

Disorders involving deficiencies in blood clotting or inappropriate blood clotting.

What can cause clotting deficiencies?

Malnutrition, leukemia, and gallstones.

What happens if a clotting factor is deficient?

The coagulation cascade may stop.

What is hemophilia?

A family of hereditary clotting-factor deficiencies that impair normal blood clotting.

Why does hemophilia occur mostly in males?

Most forms of hemophilia are caused by sex-linked recessive traits.

What is hemophilia A?

Classic hemophilia caused by a deficiency of clotting factor VIII.

What percentage of hemophilia cases are hemophilia A?

About 83%.

How common is hemophilia A?

About 1 in 5,000 males worldwide.

What is hemophilia B?

A form of hemophilia caused by a deficiency of clotting factor IX.

What percentage of hemophilia cases are hemophilia B?

About 15%.

How common is hemophilia B?

About 1 in 30,000 males.

What is hemophilia C?

A rarer form of hemophilia caused by a deficiency of factor XI.

Is hemophilia C sex-linked?

No.

How can hemophilia A be treated?

Purified factor VIII can be used to replace the missing clotting factor.

Why was hemophilia historically very dangerous?

Before purified factor VIII was available, more than half of hemophiliacs died before age 5 and only about 10% lived to age 21.

What can repeated bleeding into muscles and joints cause?

Terrible pain and eventual joint immobility due to hematomas.

What level of normal factor VIII prevents symptoms of hemophilia A?

About half of the normal level.

How severe are symptoms when factor VIII is about 30% of normal?

Symptoms are generally mild.

How can bleeding from hemophilia be temporarily relieved?

By transfusion of plasma or purified clotting factors.

What is thrombosis?

Abnormal clotting in an unbroken blood vessel.

What is a thrombus?

A blood clot that forms within a blood vessel.

What can happen if a thrombus grows?

It can become large enough to obstruct a blood vessel.

What is an embolus?

A clot or other material that travels through the bloodstream.

How does an embolus form from a thrombus?

A piece of a thrombus can break away and travel through the bloodstream as an embolus.

What can happen when an embolus becomes lodged in an artery?

It can block blood flow.

What is infarction?

Tissue death caused by blockage of blood flow.

What serious conditions are commonly caused by thrombosis?

Many strokes and heart attacks.

Which blood vessels are more likely to develop thrombosis?

Veins, because blood flows more slowly through them.

Where is venous thrombosis especially common?

In the veins of the legs of inactive people and patients confined to wheelchairs or beds.

Why does immobility increase the risk of venous thrombosis?

Reduced movement slows blood flow through the veins.

Where do many clots originating in the limbs travel?

To the heart and then the lungs.

What is a pulmonary embolism?

An embolus that lodges in the pulmonary circulation and blocks blood flow through the lungs.

What can a pulmonary embolism cause?

Hypoxia and potentially death.

What is thromboembolism?

A condition involving a thrombus that breaks loose and becomes an embolus.

What percentage of people die from unwanted blood clotting compared with clotting failure?

The chapter states that far more people die from unwanted blood clotting than from clotting failure.

What is the danger of an embolus blocking an artery?

It can stop blood flow and cause tissue death (infarction).

What are the three major arteries mentioned in relation to fatal thromboembolism?

Cerebral, coronary, and pulmonary arteries.

Approximately how many Americans does the chapter state die each year from thromboembolism?

About 650,000.

Why are venous clots particularly dangerous?

They can travel to the lungs and cause a potentially fatal pulmonary embolism.