When a patient is first diagnosed with TTP, it may be difficult to understand what has happened and what the diagnosis means. For most patients the diagnosis will arrive suddenly and unexpectedly.

Although current treatments have saved many lives, patients with TTP continue to die from the condition.1,4,5

A physician is always the best source of information about diagnosis and treatment.

TTP episodes are a medical emergency, and can be sudden and unexpected

Key points

  • Early diagnosis of TTP is crucial, as without treatment 90% of patients die
  • Diagnosis is normally made by a combination of medical history, physical examinations and diagnostic tests
  • Two important markers that may be monitored both throughout treatment and after treatment are platelet count & ADAMTS13 levels

Diagnosing TTP

In TTP, early and precise diagnosis is critical to successfully treating patients.1,2 When patients with TTP arrive at hospital, the most important thing is for their doctors to recognise and diagnose TTP as quickly as possible.1,2

However, one of the greatest challenges associated with TTP is that it is a very difficult condition to diagnose.1,6 Patients may be young and healthy, without any previous history of serious medical conditions. They often first go to their doctor with general flu-like symptoms, that do not point directly to TTP.1

When their condition gets more serious and they arrive at hospital, their wide range of symptoms could apply to many different types of conditions making it a challenge to recognise and diagnose TTP.1 This challenge is made even more difficult because TTP is so rare.

Diagnosis is normally made by a combination of medical history, physical examinations and diagnostic tests:1

  • The medical history may indicate to the doctor that some of the potential triggers for TTP are present – such as having certain diseases or conditions, or having taken certain medications
  • The physical examination may reveal some of the common symptoms of TTP such as bruising under the skin, yellowing of the skin, changes in the colour of the urine or neurological symptoms such as headaches or confusion
  • The diagnostic tests will help the doctor identify some other signs of TTP, such as low platelet count, low red blood cell levels and indications that some organs are not functioning properly
TTP patient story by Jo

Jo, UK patient

Patient story

...I was initially diagnosed in 1995. The first signs were big colorful bruises on my legs.

Diagnosing inherited TTP

Inherited TTP is normally distinguished from aTTP by testing a patients’ ADAMTS13 enzyme activity (how well the patients’ ADAMTS13 enzyme is working) and by testing for antibodies against ADAMTS13.In both forms of TTP, a patient will have low levels of ADAMTS13 activity but in inherited TTP, there will be no antibodies present – antibodies are only present in aTTP.1

A diagnosis of inherited TTP can then be confirmed by genetic testing.People with inherited TTP may also be diagnosed based on their family history. If a person is diagnosed with inherited TTP, then all their siblings may also be tested as patients may have inherited TTP without displaying any signs or symptoms.1

Understanding your platelet count & ADAMTS13 levels

For patients with TTP, there are two important markers that may be monitored both through treatment and after treatment has finished and they are in remission.

1. Platelet count

When a patient has been diagnosed with TTP, their platelet count will be an important marker of how their treatment is progressing.

TTP results in low platelet counts in the blood causing a range of symptoms for patients. As treatment progresses, platelet counts should rise until they reach a normal level.

What is a normal platelet count?

  • A normal platelet count is between 150-450 billion platelets per litre of blood. This may be written as 150-450 109 /L
  • During episodes of TTP, patients often have platelet counts of 20-50 billion platelets per litre of blood (20-50 109 /L)

Patients’ platelet counts may continue to be monitored once the patient has recovered from their initial episode of TTP.

Platelet counts are measured in terms of the number of platelets per litre of blood

2. ADAMTS13 levels

The second important marker for patients with TTP is their ADAMTS13 enzyme levels. In TTP, the ADAMTS13 enzyme does not function as it should, either because the gene that produces ADAMTS13 is faulty or because the body produces antibodies that stop it from working.Your doctors can measure how well ADAMTS13 is working (also called ADAMTS13 activity). They may do this when a patient first arrives in hospital to confirm the diagnosis of TTP and they may also do it after treatment has finished as low ADAMTS13 activity may indicate an increased risk of a recurrence.1


There is an important reason why platelet & ADAMTS13 levels are monitored after treatment has finished and a patient is in remission. This is to try to prevent relapses.

Relapses are further episodes of TTP after a patient has recovered from their initial episode (more than 30 days after last treatment with daily plasma exchange). Unfortunately, relapses are a common feature of TTP: it is estimated that 30-50% of patients with TTP will have a recurrence.Many patients may also find that fear of relapses may affect their quality of life. Why relapses occur and which patients are likely to experience relapses is something that is not fully understood.8