Thrombotic thrombocytopenic purpura (TTP) and immune thrombocytopenia (ITP) are both blood disorders that affect blood clotting. TTP is more serious than ITP.
The term “thrombocytopenia” refers to low levels of platelets, the cells that help with blood clotting. “Purpura” refers to when small blood vessels burst below the skin, leading to blood pooling beneath the skin and a rash.
While these conditions share some symptoms, such as bruising and tiredness, they differ in how urgently they require treatment.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Learn more.
TTP is a life threatening blood disorder. In this condition, blood clots form in the small blood vessels throughout the body. These clots can block or slow the flow of blood, restricting the amount that reaches important organs.
Raised levels of clotting use up a lot of a person’s platelet levels, which means there might not be enough available to deal with injuries, which in turn can lead to bruising.
TTP can either be inherited or acquired. Inherited TTP is present from birth and passes on genetically. Acquired TTP develops during a person’s lifetime.
Inherited TTP
- tends to affect adults
- affects females more often than males
- occurs more often among African Americans than people with other racial identities in the United States
It is important to note that research suggests African Americans with inherited TTP have a higher relapse rate and shorter relapse-free survival time after the first episode of the condition compared with white people.
A 2022 study also indicates that race affects overall relapse risk and response to rituximab, a medication doctors may use off label to treat thrombocytopenia.
The researchers suggest state that Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab.
They also identify a lack of studies into how racism and social determinants of health contribute to this racial disparity in relapse risk.
ITP is a blood disorder where a person’s immune system attacks their platelet cells, leading to low platelet levels. Doctors may also refer to ITP as idiopathic immune thrombocytopenia and autoimmune thrombocytopenic purpura.
For
Short-term ITP is most common and typically affects children. Long-term ITP mostly affects adults and affects females two to three times more often than males.
The table below summarizes the key features of TTP and ITP:
| TTP | ITP | |
|---|---|---|
| Reason for low platelet levels | increased blood clotting in small blood vessels | immune system targeting platelet cells |
| Symptoms | symptoms can occur suddenly, including shortly after birth, and • flat spots under the skin • bruising • yellowing of the whites of the eyes • extreme tiredness • lack of urination • bloody urine • sickness and diarrhea • fever • racing heart rate • shortness of breath • headaches • speech changes • confusion • seizure • coma | symptoms may not occur, but can • flat spots under the skin • bruising • extreme tiredness • nosebleeds • bleeding gums • bloody urine or stool • heavy menstrual bleeding |
| Risk factors | • age • sex • race and ethnicity • family history of TTP • infection • pregnancy • certain medications • certain medical procedures • cancer • lupus • obesity | • age • sex • infection • certain vaccines • certain medications |
| Diagnosis | • various blood tests • bone marrow tests • kidney function tests • urine tests | • various blood tests • bone marrow tests |
| Treatment | • plasma treatments • medication to increase platelet levels • spleen removal | • medication to increase platelet levels • spleen removal • platelet transfusion |
TTP and ITP have very different causes.
TTP causes
TTP occurs due to a shortage of an enzyme called ADAMTS13, which is responsible for controlling blood clotting. This shortage leads the body to form too many clots.
People can have a shortage of ADAMTS13 due to either:
- inheriting a mutated gene from both biological parents
- another disease or condition leading to the creation of antibodies that stop ADAMTS13 working properly
ITP causes
ITP occurs when the immune system targets and destroys platelet cells. As a result, experts consider it an autoimmune condition.
People with ITP may also produce fewer platelet cells, though scientists are currently unsure why this might happen.
Many of the tests doctors use to diagnose TTP and ITP are the same. However, doctors may request several additional tests to investigate a possible case of TTP.
Tests for TTP
Due to the potential severity of TTP, it is important for doctors to diagnose the condition quickly.
Blood tests they may request include:
- a complete blood count to check the levels of different types of blood cells
- a Coombs test to look for antibodies that destroy red blood cells
- a blood smear to examine the shape of blood cells
- an ADAMTS13 activity test
The may also test a person’s:
- bone marrow
- kidney function
- bilirubin
- urine
Tests for ITP
Diagnosing ITP requires fewer tests than TTP. A doctor may request:
- a complete blood count
- a blood smear
- a bone marrow test
TTP requires urgent treatment, while ITP may not require treatment at all.
TTP
An important form of treatment for acquired TTP is plasmapheresis, which involves:
- giving the person plasma from a donor using a machine that also filters the blood
- removing antibodies in the blood that affect the ADAMTS13 enzyme
- providing fresh ADAMTS13
People with inherited TTP will receive a plasma infusion, where doctors supply donor plasma directly to a vein. This also helps increase ADAMTS13 levels.
Other treatment options for TTP include:
- Corticosteroids: These medications increase platelet levels and restrict the production of antibodies affecting ADAMTS13.
- Caplacizumab-yhdp (Caplivi): This medication restricts blood clots from forming in specific areas.
- Spleen removal: Surgeons can remove this organ to stop your body from making certain antibodies.
- Genetic counseling: Experts can provide advice and guidance for people with inherited TTP.
ITP
Treating ITP will depend on the symptoms a person experiences and what their platelet levels are like. Mild cases
If required, treatment aims to increase a person’s platelet levels. Options include:
- corticosteroids
- platelet transfusion
- spleen removal
Learn more about treatments for low platelet counts.
The potential complications of untreated TTP are significantly more severe than those of untreated ITP.
TTP
Without treatment, TTP can cause blood clots to reduce blood flow to a person’s organs. This
- stroke
- heart attack
- kidney problems
- digestive issues
- brain damage
- seizures
- coma
ITP
ITP can make episodes of bleeding more severe. In rare cases, bleeding into the brain can occur.
The outlook for a person with TTP is quite different from that of someone with ITP.
TTP
Acquired TTP can last for a few weeks, but may persist for a few months in some cases.
The outlook for a person with TTP depends on whether or not they receive treatment for the condition. Without treatment, TTP can cause long-term health issues. It can even be fatal in some instances. Appropriate early treatment reduces the risk of death from
Many people will make a full recovery after receiving treatment for TTP. However, relapses can occur with both the inherited and acquired forms of the condition.
ITP
Many short-term cases of ITP resolve without treatment in
Long-term cases last for more than 6 months and require treatment. Some cases can last for years.
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Thrombotic thrombocytopenic purpura (TTP) and immune thrombocytopenia (ITP) are blood disorders that reduce a person’s platelet count, which can lead to noticeable changes in the skin and bruising.
While both conditions reduce platelet levels, they have different causes. TTP occurs due to an increase in blood clotting because of a shortage of a certain enzyme in the body. ITP occurs when the immune system targets platelet cells as though they were a threat.
TTP can be a very serious condition that requires prompt treatment. ITP sometimes does not require treatment at all.