Thrombotic Thrombocytopenic Purpura (TTP) is a rare blood disorder, with between 1.2 and 11 new cases every year per million of the population. It is more common in women than men and, although it can affect people of all ages, the average age of diagnosis is 40 years.

TTP episodes are serious and life-threatening. It is considered a medical emergency and it is estimated that 10-20% of acute patients die from TTP, despite currently available treatments. TTP is a lifelong condition, as after their initial diagnosis many patients will experience further episodes of TTP (called relapses).

There are two main types of TTP – inherited TTP and acquired TTP

Key Points

  • TTP is a serious, rare and potentially life-threatening condition
  • 30%-50% of patients will experience multiple episodes of TTP (called relapses) after their initial diagnosis
  • It occurs when the ADAMTS13 enzyme does not function as it should, leading to small blood clots in the blood vessels, low platelet counts and destruction of red blood cells
  • It is not known what causes the body to start producing antibodies against ADAMTS13 in acquired TTP
  • Patients with TTP may experience a wide variety of symptoms, including fever, fatigue, headache, confusion and bruises or dots on the skin
  • There are two main types of TTP – inherited TTP and acquired TTP


The name thrombotic thrombocytopenic purpura actually describes three of the main features of the condition:

  1. Thrombotic refers to the formation of a blood clot inside a blood vessel.
  2. Thrombocytopenic refers to a condition in which the number of platelets in the blood is lower than normal.
  3. Purpura refers to purple bruises caused by bleeding underneath the skin.

However, these three features only tell part of the story of TTP. To fully understand how TTP affects the body, we first need to look in more detail at some of the components of blood. With TTP, we are interested in three components in particular:

  1. Platelets.
  2. A protein called von Willebrand Factor (vWF) that is present in blood plasma.
  3. An enzyme called ADAMTS13 that is also found in the blood plasma.

Diagnosis & Symptoms

Thrombotic Thrombocytopenic Purpura (TTP) is known, in the majority of patients, as an autoimmune condition. It is a rare blood disorder that affects between 6 to 10 people in every million. It was first described in 1924 by Dr Eli Moschcowitz who had been treating a 16 year old female patient who was in a coma and had kidney failure. She died within 2 weeks. Moschcowitz described the characteristics of TTP based on his patient’s post mortem results. Survival rates have improved greatly since 1924. With accurate diagnosis and prompt treatment, current survival rates are approximately 80%.

People with TTP have a deficiency of the enzyme that should break down the von Willebrand Factor, which, with platelets, normally prevents bleeding. This enzyme stops working properly and the platelets become sticky and form blood clots in small vessels that can affect any organ.

Doctors will look for low platelet and low haemoglobin count. The following tests are done as a matter of routine when treating a TTP Patient:

  • Full Blood Count (Platelets and red cells or haemoglobin)
  • Reticulocyte (immature red blood cells)
  • Clotting screen
  • Renal & Liver function
  • LDH (marker of tissue breakdown)
  • Secondary conditions such as HIV or Hepatitis
  • Blood Group (for blood supplies)
  • Pregnancy test (known trigger of TTP)

Symptoms can be very variable and may be a common complaint such as flu-like, tiredness; but patients may report having some of the following symptoms prior to diagnosis:

  • Headaches
  • Confusion
  • Anxiety
  • Stomach upset
  • Fever
  • Disturbed vision
  • Stroke-like symptoms

Acquired TTP

A patient with Acquired TTP will have a trigger that sets off the TTP episode. If you have acquired TTP you will have been susceptible for some (as yet unknown) reason to getting the condition, and the trigger will have brought on the episode of TTP. Here are some known triggers:

  • Combine contraceptive pill
  • Viral infections
  • Pregnancy
  • Quinine
  • HIV
  • Ticlopidine
  • Interferon
  • Simvastatin
  • Acquired TTP
  • Inherited TTP

More commonly, people aren’t born with faulty genes but instead develop TTP at some point later in their lives.

This is called Acquired TTP or immune-mediated TTP. In Acquired TTP, the body’s immune system starts producing antibodies that stop ADAMTS13 from working. Acquired TTP accounts for around 95% of all cases of TTP.

However, in most patients with acquired TTP, they have no obvious triggering factor. TTP affects both male and females, 2/3rds of patients are females and all age groups although it is most commonly seen in the 3rd and 4th decade. The best-known treatment for TTP is plasma exchange therapy. Whole platelets should not be given to a TTP patient as this effectively feeds the disease.

Inherited TTP

People with Inherited (also called congenital) TTP are born with the condition. It remains with them throughout their life. There is a mistake in the gene that tells the body how to make the enzyme ADAMST13, therefore, the ADAMST13 is missing. It affects males and females equally, and the condition is inherited from parents where each parent has half of the nonworking gene. The parents will not have the condition themselves as they only have half of the nonworking gene. Congenital TTP is even rarer than the acquired form. As of 2007, there are approximately 15 cases in the UK. Symptoms of a patient (baby or small child) with congenital TTP include:

  • Jaundice. An exchange transfusion using whole blood may be needed
  • Low platelet count
  • Aneamia
  • Tummy upset
  • Fever
  • Petechiae or purpura (red pinprick rash)

Like Acquired TTP, it is not clear what triggers inherited TTP in all patients – some patients show the signs and symptoms at birth while others do not show them until adulthood. As with Acquired TTP, there are certain factors, such as pregnancy or infection, that seem to play a role in triggering inherited TTP.