Published: 18 Jun 2025

ICD9: 446.6      ICD10: M31.1      ICD11: 3B64.14

Thrombotic Thrombocytopenic Purpura (TTP) is a rare and life-threatening blood disorder characterized by the formation of small blood clots throughout the body.
These clots can block small blood vessels, leading to serious health problems.

Here's a breakdown of the key aspects of TTP:

What the words mean:

Thrombotic: Relating to or involving the formation of a thrombus (blood clot).
Thrombocytopenic: Having a low platelet count (thrombocytes are platelets).
Purpura: Purple spots or bruises on the skin caused by bleeding under the skin.

Key Features of TTP:

Thrombocytopenia (Low Platelet Count): Platelets are consumed in the formation of the small blood clots, leading to a decrease in the number of platelets circulating in the blood. This increases the risk of bleeding.

Microangiopathic Hemolytic Anemia (MAHA): Red blood cells (RBCs) are damaged and destroyed as they squeeze through the narrowed, clot-filled blood vessels. This results in anemia (low RBC count) and the fragmented RBCs, called schistocytes, can be seen under a microscope.

Organ Damage: The small blood clots can block blood flow to various organs, including the brain, kidneys, and heart, potentially causing serious damage and dysfunction.

Causes of TTP:

There are two main types of TTP, each with a different underlying cause:

Acquired TTP (Autoimmune TTP): This is the more common form. It occurs when the body's immune system mistakenly produces antibodies that block or destroy the ADAMTS13 enzyme. ADAMTS13 is responsible for cleaving von Willebrand factor (vWF), a protein involved in blood clotting. When ADAMTS13 is deficient, vWF becomes abnormally large and sticky, leading to platelet aggregation and clot formation.

Congenital TTP (Inherited TTP or Upshaw-Schulman Syndrome): This is a rare, inherited form of TTP caused by a genetic mutation in the *ADAMTS13* gene. Individuals with congenital TTP are born with a deficiency of the ADAMTS13 enzyme.

Symptoms of TTP:

Symptoms can develop suddenly and vary in severity. They may include:

Purpura (small, reddish-purple spots on the skin) and/or bruising: Due to low platelet count.
Fatigue and weakness: Due to anemia.
Pale skin (pallor): Due to anemia.
Headache, confusion, seizures, or stroke: Due to blood clots in the brain.
Fever: May be present.
Abdominal pain, nausea, vomiting, or diarrhea: Due to clots in the digestive system.
Dark urine: Due to kidney damage.
Jaundice (yellowing of the skin and eyes): Due to the breakdown of red blood cells.

Diagnosis of TTP:

Diagnosis typically involves:

Blood tests:
Complete blood count (CBC) to check platelet count, red blood cell count, and presence of schistocytes.
Peripheral blood smear to examine blood cells under a microscope.
ADAMTS13 activity level: This test measures the level of the ADAMTS13 enzyme in the blood. A severely low level strongly suggests TTP.
ADAMTS13 inhibitor assay: This test checks for the presence of antibodies that inhibit ADAMTS13.
Kidney function tests.

Other tests: May be needed to rule out other conditions or assess organ damage.

Treatment of TTP:

TTP is a medical emergency that requires prompt treatment. The main goals of treatment are to remove the antibodies causing the ADAMTS13 deficiency and prevent further clot formation. Treatment typically includes:

Plasma Exchange (PEX): This is the primary treatment for acquired TTP. It involves removing the patient's plasma (the liquid part of blood) and replacing it with healthy plasma from a donor. This removes the antibodies and replenishes the ADAMTS13 enzyme.

Immunosuppression: Medications such as corticosteroids (e.g., prednisone) and rituximab are used to suppress the immune system and reduce antibody production.

Caplacizumab: A monoclonal antibody that binds to von Willebrand factor, preventing it from interacting with platelets and forming clots. It's often used in combination with plasma exchange.

In congenital TTP: Plasma infusions are used to provide the missing ADAMTS13 enzyme.

Prognosis:

With prompt diagnosis and treatment, the prognosis for TTP has improved significantly. However, TTP can still be life-threatening, especially if left untreated. Relapses can occur, requiring further treatment. Long-term follow-up is important to monitor for complications and recurrence.

In summary, TTP is a rare and serious blood disorder characterized by low platelet count, hemolytic anemia, and organ damage caused by small blood clots. Prompt diagnosis and treatment, especially plasma exchange, are crucial for improving outcomes.

Important Note: This information is for educational purposes only and should not be considered medical advice. If you suspect you have TTP, seek immediate medical attention.