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Thrombotic Thrombocytopenic Purpura (TTP)


David J. Kuter

, MD, DPhil, Harvard Medical School

Reviewed/Revised Jun 2022 | Modified Sep 2022

Thrombotic thrombocytopenic purpura (TTP) is a serious disorder that involves the formation of small blood clots throughout the body that block the flow of blood to vital organs such as the brain, heart, and kidneys.

  • Symptoms are related to where in the body blood clots form.

  • Diagnosis is based on the person's symptoms and blood tests.

  • Treatment of TTP is with plasma exchange, corticosteroids, rituximab, and rarely caplacizumab.

Thrombotic means that blood clots form, thrombocytopenic means the platelet count is low, and purpura means that purple spots or bruises appear on the skin. Thrombotic thrombocytopenic purpura (TTP) is a rare disorder in which many small blood clots (thrombi) form suddenly throughout the body. It is related to hemolytic-uremic syndrome Hemolytic-Uremic Syndrome (HUS) Hemolytic-uremic syndrome (HUS) is a serious disorder that usually occurs in children and involves the formation of small blood clots throughout the body that block the flow of blood to vital... read more (HUS), but it is more likely to occur in adults than HUS, which is more common in children.

The blood clots in TTP are not large clots that block large blood vessels, like in deep vein thrombosis Deep Vein Thrombosis (DVT) Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs. Blood clots may form in veins if the vein is injured, a disorder causes the blood to clot... read more Deep Vein Thrombosis (DVT) . Instead, in TTP, there are many small clots that block small blood vessels throughout the body, particularly those in the brain, heart, and kidneys. The blood vessel blockage damages organs and can break apart red blood cells that pass through partially blocked vessels. The blood clots also use up an abnormally high number of platelets, which leads to a sharp decrease in the number of platelets in the bloodstream (termed thrombocytopenia Overview of Thrombocytopenia Thrombocytopenia is a low number of platelets (thrombocytes) in the blood, which increases the risk of bleeding. Thrombocytopenia occurs when the bone marrow makes too few platelets or when... read more Overview of Thrombocytopenia ).

The cause of TTP is often unknown, but some people develop it after taking certain drugs (including quinine, cyclosporine, and mitomycin C), after certain types of intestinal infection, during pregnancy, or rarely as an inherited disease. In most people, TTP is an autoimmune disorder Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more in which the body's immune system creates antibodies that destroy an enzyme (ADAMTS13). When this enzyme is deficient, platelets start to clot inappropriately within blood vessels, the number of platelets in the blood (platelet count) decreases, and the organs in which the clots occur (such as the brain and kidneys) can be damaged.

Symptoms of TTP

In thrombotic thrombocytopenic purpura (TTP), symptoms develop suddenly.

Symptoms in TTP are quite distinct from symptoms of most other forms of thrombocytopenia.

In TTP, the small blood clots that develop (using up platelets) cause a wide range of symptoms and complications, some of which can be life threatening. Symptoms that result from clots in the brain may include headache, confusion, seizures, and coma. Symptoms that result from clots in the brain may come and go and may vary in severity. Symptoms that result from clots elsewhere in the body include abnormal heart rhythms, blood in the urine, and abdominal pain.

Diagnosis of TTP

  • Blood tests to measure platelet count and ADAMTS13 enzyme levels

  • Tests for autoantibodies against the ADAMTS13 enzyme

  • Tests to rule out other disorders that cause a low platelet count and bleeding

Doctors suspect thrombotic thrombocytopenic purpura (TTP) when they find a low platelet count in people who have been ill, who have taken certain drugs, or who are pregnant.

Although there are no blood tests that specifically diagnose TTP, doctors do a number of blood tests that, together with people's symptoms, help make the diagnosis. These blood tests often include tests demonstrating that red blood cells are being destroyed, tests to see how well the kidneys are working, and often tests to measure ADAMTS13 enzyme levels and the presence of antibodies against the enzyme.

Treatment of TTP

  • Corticosteroids and plasma exchange

  • Sometimes the drug rituximab

  • Caplacizumab (rarely)

With thrombotic thrombocytopenic purpura (TTP), people are often treated with corticosteroids and plasma exchange (plasma transfusions along with plasmapheresis Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more ). In plasmapheresis, blood is taken from the person and put in a machine that separates the blood cells from the liquid part of the blood (plasma). The plasma, which contains disease-causing antibodies, is discarded and the blood cells are returned to the person along with fresh plasma obtained from health donors.

Rituximab is a drug that suppresses the immune system and is often used in people with TTP to prevent relapse after being treated with corticosteroids and plasmapheresis.

Caplacizumab is a drug that inhibits the interaction between a protein involved in clotting and platelets. Although caplacizumab may reduce the need for plasma exchange and speed recovery in TTP, it may increase the risk of bleeding.

Drugs Mentioned In This Article

Generic Name Select Brand Names
RIABNI, Rituxan, RUXIENCE, truxima
Cequa, Gengraf , Neoral, Restasis, Sandimmune, SangCya, Verkazia
JELMYTO, Mitosol, Mutamycin
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