Immune Thrombocytopenia (ITP): What You Need to Know

Immune thrombocytopenia (ITP) is a platelet disorder that develops when your blood does not clot the way it should because of a low platelet count. It is rare, and it can be hard to understand at first. Here is a plain-language look at what is happening in your body, why it happens, and what it can mean for you.¹

What platelets do

Platelets are small, disc-shaped cells that travel in your blood. When they recognize a damaged blood vessel, they bind together and form a clot to stop the bleeding.²

A normal platelet count is between 150,000 and 450,000 per microliter of blood. When your count drops, your blood does not clot as easily. That is why bruising and bleeding are the signs most people notice first.²

What happens in ITP?

In ITP, your immune system attacks and destroys your own platelets by mistake. Your immune cells make antibodies that attach to your platelets. Your body then destroys the platelets carrying those antibodies, mostly in the spleen.^1,3
If your platelet count is lower than 100,000 per microliter and there is no other reason for it, you are considered to have ITP.²

Primary and secondary ITP

Doctors sort ITP into 2 groups:⁴

• Primary ITP – The immune system attacks platelets on its own, with no other condition behind it. This accounts for about 80 percent of cases.
• Secondary ITP – The low platelet count happens alongside another condition, such as HIV, hepatitis C, an H. pylori infection, a blood cancer, or another autoimmune disorder.

Other things can play a role, too. Some antibiotics, antivirals, and anti-inflammatory drugs are linked to ITP. So are viral and bacterial infections, immune conditions such as lupus, and, rarely, vaccines such as the MMR vaccine.¹

How long ITP lasts

ITP is also described by how long it lasts:⁴

• Acute ITP – Goes away within 3 months. This type is more common in children.
• Persistent ITP – Lasts 3 to 12 months.
• Chronic ITP – Lasts longer than 12 months. This type is more common in adults.

Who gets ITP?

Studies have shown that the rate of ITP among children is about 4 per 100,000. Among adults, the rate of ITP is about 3 per 100,000. Adult women have a higher rate of ITP diagnosis than adult men, but rates among boys and girls are relatively equal. ITP is likely under-diagnosed because many people have mild or no symptoms and do not seek medical attention.⁵

Your risk of developing ITP is higher if you have another autoimmune condition, such as rheumatoid arthritis or lupus. If you have a close family member – such as a parent or a sibling – with ITP, you are also at an increased risk.^5,6

What ITP can feel like

Many people with ITP have no symptoms at all. When symptoms do show up, they may include:^1,4

• Petechiae – Tiny red or purple dots on your skin, often on your lower legs, that can look like a rash.
• Purpura – Larger red or purple patches that form when petechiae run together.
• Bruises you cannot explain – Including large bruises under the skin.
• Bleeding – From your nose or gums, or in your urine or stool.
• Heavy menstrual periods – Bleeding that is heavier than usual.
• Fatigue – Feeling worn out, which can also come from low red blood cell counts.

Symptoms do not always match the number on your lab report. Some people have very low counts and few symptoms.⁶

What ITP means going forward

There is no cure for ITP. Even so, adults with persistent or chronic ITP can live for decades with the right care and follow-up. With treatment, the chance of remission, meaning a stretch of time with no symptoms, is good. For most children and adults, ITP is not a serious condition.^1,3,4

Talking with your doctor

Bring your questions to your next appointment, and share what you have noticed in your body, not just what your lab numbers say. Ask what your platelet count means for you, whether you need treatment now, and what warning signs should prompt a call. You do not have to sort this out alone.