Acquired Thrombotic Thrombocytopenic Purpura (aTTP)

Medically Reviewed by Nayana Ambardekar, MD on September 04, 2022
5 min read

Acquired thrombotic thrombocytopenic purpura (acquired TTP, or aTTP) is a rare blood disorder that results in blood clots in small blood vessels around your body. These clots can slow the flow of oxygen-rich blood to your heart, brain, kidneys, and other organs.

The disease affects platelets, blood cells that stick together to help your blood clot when you cut yourself. They help seal the cut and prevent bleeding.

In aTTP, platelets clump together and form small clots when they shouldn't. This leaves fewer platelets in your body, which is why you may bleed more than usual. Sometimes red blood cells break apart. This causes a low red blood cell count, called anemia.

Acquired TTP can be serious. But there are treatments to prevent it from coming back. You'll have the best chance if you get treated as early as possible and see your doctor after treatment for regular follow-up visits.

Acquired TTP is an autoimmune disorder, which means your body mistakenly attacks itself. The immune system releases proteins called antibodies that target ADAMTS13, an enzyme that normally prevents your blood from clotting too much. Doctors don’t know what triggers the autoimmune reaction that leads to aTTP.

Acquired TTP can make you bleed inside your body and under your skin. If you cut yourself, it may be hard to stop the bleeding. It can also cause clots in your blood vessels.

Blood clots and bleeding inside the body cause symptoms like:

  • Purple-colored bruises under the skin, called purpura
  • Tiny red or purple dots under the skin, called petechiae
  • Pale or yellow skin color
  • Tiredness and weakness
  • Shortness of breath
  • Fever
  • Confusion
  • Slurred speech
  • Headache
  • Fast heartbeat

These symptoms start quickly and can last for days or weeks.

Your primary care doctor may refer you to a specialist who treats blood disorders, called a hematologist.

The doctor will first ask about your medical history, including what diseases you've had and the medicines you've taken. During the exam, your doctor will look for aTTP symptoms like pale skin, bruising, and shortness of breath.

Blood tests can confirm the diagnosis. One measures the activity of the enzyme ADAMTS13. Other tests count the number of platelets, red blood cells, and white blood cells in your blood.


  • Do I need to see a hematologist to treat my aTTP?
  • What might have caused this disease?
  • What kind of treatment do I need?
  • For how long will I need to stay in the hospital for treatment?
  • What side effects can the treatments cause? How can I manage side effects?
  • What follow-up care will I need after my treatment is finished?


Plasma exchange is one of the main treatments for aTTP. You'll go to a hospital for this treatment as soon as you're diagnosed with aTTP.

Plasma is the liquid part of your blood. It contains platelets, red blood cells, and white blood cells.

During plasma exchange, first a small amount of your blood is drawn with a needle. It's kind of like getting a blood test. Your blood passes through a machine that separates out the plasma from the other blood cells.

The machine removes the faulty antibodies from your blood that were attacking the ADAMTS13 enzyme. It replaces damaged enzymes with healthy enzymes from a donor. The plasma then goes back into your body, along with your own blood cells that were removed. The procedure takes about 2 hours.

Your doctor may prescribe steroid medicines along with plasma exchange. Steroid drugs reduce the immune system response to stop your body from targeting ADAMTS13.

You'll get plasma exchange treatment every day until your platelet count goes back to normal. This can take a few days or weeks. You'll stay in the hospital during this time.

Once your blood count is normal, you'll stop the treatment. If you were on steroids, your doctor will slowly lower the dose over a period of 2 to 3 weeks.

Other medications can treat aTTP as well. These include caplacizumab (Cablivi) and rituximab (Rituxan). These drugs are called monoclonal antibodies. But they don’t work quite the same.

  • Caplacizumab prevents platelets from clumping together, which prevents the small clots. You’ll get it through an IV the first time, but after that, it’ll be a shot under your skin. It can be used along with drugs that suppress your immune system. You may get it as soon as you start plasma exchange.
  • Rituximab, like steroids, suppresses your immune system. You get it in an IV through a tube that goes under your skin.

Both steroid drugs and rituximab can have side effects like:

  • Increased pressure in the eyes
  • High blood pressure
  • High blood sugar
  • Mood swings
  • Weight gain
  • Clouding of the lens in the eyes
  • Increased risk of infections
  • Thinner bones

Drugs that suppress your immune system raise your chance of having infections, which can sometimes be serious.

The most common side effects of caplacizumab include:

  • Headache
  • Fever
  • Shortness of breath
  • Fatigue
  • Back pain
  • Muscle pain
  • Tingling, prickling, or a numb feeling on the skin
  • Itching near where you got the shot


Acquired TTP can make you bruise or bleed more easily than usual. Practice good safety measures to avoid injury.

Use caution when working with sharp objects like knives or nail clippers. When you shave, use an electric razor instead of a blade. Switch to a soft toothbrush, and be very gentle when brushing your teeth.

Avoid taking NSAID drugs like aspirin and ibuprofen. They can make you bleed more easily than usual.

Call your doctor right away if you see symptoms like these:

  • Unusual bruises
  • Heavy bleeding
  • Poop that is black or looks like tar
  • Tiny purple spots on your skin
  • Pale skin
  • Shortness of breath
  • Yellowing of your skin and eyes


Acquired TTP can last for days, weeks, or even months. See your doctor for treatment as soon as you notice symptoms.

Acquired TTP can be very serious. If you don't treat it right away, it can cause complications like brain damage or a stroke. Some complications can be life-threatening.

Treatment with plasma exchange and corticosteroid drugs stops symptoms in most people with aTTP. But in up to 60% of people who've been treated, the disease comes back, or relapses. Usually the relapses happen in the first 1 to 2 years after aTTP was first diagnosed. Taking rituximab may help prevent relapses.

To watch for relapses, you'll see the doctor who treated your aTTP for regular checkups during the first few years after your diagnosis. If your symptoms come back, you'll get treated again.

To learn more about aTTP and find support groups, visit the website of the Answering T.T.P. (Thrombotic Thrombocytopenic Purpura) Foundation.