Thrombocytopenia (Low Platelet Count)

Medically Reviewed by Zilpah Sheikh, MD on October 31, 2023
11 min read

Thrombocytopenia is the condition when you don’t have enough platelets in your blood. Platelets are small blood cells that clot your blood after you get any cut or scrape that bleeds or a bigger injury.These cells stick together, which stops bleeding.

If you're wondering what the long name means, here's how it breaks down: "Thrombocytes" is another name for your platelets, and "penia" means you don't have enough of something. Put those terms together, and you get "thrombocytopenia."

A healthy person usually has a platelet count of 150,000 to 450,000 in every microliter of blood. (A single drop of blood has about 35 microliters.) You have low platelets and thrombocytopenia if your lab values fall under 150,000.

Usually, you won't feel anything when you have thrombocytopenia. The condition often has no symptoms. But when you do have symptoms, they can include:

  • Bleeding. This happens most often from your gums or nose. Thrombocytopenia also can cause heavier or longer periods or breakthrough bleeding if you have a menstrual cycle. You may also see blood in your pee or poop.
  • Blotches and bruises. You might have large areas of bleeding under the skin that don't turn white when you press on them. You also might see what looks like the bruises you get from a bump or after being hit. They could be blue or purple and change to yellow or green over time. These are caused from the inside by the sudden leaking from tiny blood vessels. The medical name for these is purpura.
  • Red, flat spots on your skin. You'll see these spots the size of a pinhead mostly on your legs and feet, and they may appear in clumps. Your doctor may call them petechiae. Petechiae don't turn white when you put pressure on them.
  • Fatigue. Low platelets by itself won't make you feel run down and tired. But other conditions that cause low platelets can leave you feeling fatigued.
  • Enlarged spleen. You'll have this if your spleen is trapping platelets, which may be one reason for your low counts.


Thrombocytopenia has many possible causes. Sometimes it runs in families, but it's rare. Low platelet counts are more often related to one of many medical conditions or medicines you take for another condition. If your low platelet counts are caused by another condition, treating the underlying problem may help.

In general, anything that makes your body make less platelets than it needs will cause low platelet counts. You also can have low counts if your body is breaking platelets down or using them up faster than it's making new ones. Your platelet counts also can be low if your spleen or another part of your body is trapping platelets more than it should.

Conditions or things that can cause your body to make too few platelets include:

  • Leukemia or other cancer types
  • Certain anemias (when your blood doesn't have enough red blood cells)
  • Viral infections, including hepatitis C or HIV
  • Certain medicines or treatments, including chemotherapy or radiation
  • Drinking too much alcohol 
  • Toxins, including pesticides or arsenic

Conditions or things that can cause your body to break platelets down too fast include:

  • Pregnancy
  • Autoimmune diseases, including lupus or rheumatoid arthritis
  • Bacterial or viral infections
  • Medicines that make your immune system destroy platelets
  • Certain rare conditions, including thrombotic thrombocytopenic purpura or hemolytic uremic syndrome

Conditions or things that can cause too many of your platelets to get lost or trapped include:

  • Alcohol abuse or alcohol use disorder
  • Bleeding or hemorrhage
  • Pregnancy
  • Liver disease
  • Blood clots in your lungs (pulmonary embolism)
  • High blood pressure in your lungs (pulmonary hypertension)

What are the most common low platelet count causes?

The most common reason for low platelet counts is another health condition or a medicine you're taking for another health condition. Some other risk factors for low platelets include:

  • Family history 
  • Genetics
  • Age

You can have different types of thrombocytopenia depending on what's causing your low platelet counts:

Immune thrombocytopenic purpura (ITP)

One of the most common causes of low platelets is a condition called immune thrombocytopenia purpura (ITP). You may hear it called by its old name, idiopathic thrombocytopenic purpura. "Purpura" means that your skin looks purple like it's bruised. Although doctors don't know why ITP happens, the problem is that your immune system isn't working right. Your antibodies, which should attack infections, destroy your platelets by mistake.

ITP comes in two types: acute and chronic. Acute ITP usually happens in kids after a virus like chickenpox. It comes on fast and goes away in weeks or months. You probably won't need any treatment, and it usually won't come back. Chronic ITP means you'll have it for 6 months or more. Chronic ITP is more common in adults than it is in kids. But teens also can get it. 

Thrombotic thrombocytopenic purpura (TTP)

TTP doesn't happen a lot, but it's dangerous when it does. When you have TTP, you'll get many blood clots throughout your body. These clots can make your organs not work right or damage them. The reason you'll have low platelet counts in your blood is that they're being used up in all the clots. TTP usually lasts for days, weeks, or even months. Without treatment, it can lead to brain damage, stroke, or death.

Drug-induced thrombocytopenia (DIT)

Medicines can cause low platelet count. This happens a lot, but doctors don't always realize a drug is why you have low platelet counts. More than 300 drugs can cause low platelets.

Usually you'll have this type of thrombocytopenia 1-2 weeks after you start a new drug. But certain drugs may cause it after you take it the first time. If a drug is causing your low platelet count, it usually will go away after you stop taking it.

Heparin-induced thrombocytopenia (HIT)

This type happens when you take a drug called heparin. Doctors use heparin to protect against blood clots when you're at risk for a dangerous clot due to surgery or another condition. It can happen when the drug makes your platelets clump up instead of staying in your blood. It usually happens 2-3 days after you take heparin the first time. Sometimes your immune system also plays a role. HIT is the most common type of DIT. It happens most often when you're in the hospital.

Gestational thrombocytopenia

This type is the most common cause of low platelets when you're pregnant. It's not clear why pregnancy causes low platelet counts. It happens most often late in pregnancy. It usually goes away after birth. But if you've had gestational thrombocytopenia with one pregnancy, it may come back if you get pregnant again. 

Usually this type of thrombocytopenia doesn't lead to bleeding. But your doctor may want to order tests to make sure there isn't some other reason for your low platelet counts.

Dilutional thrombocytopenia

You can have low platelets after a major blood transfusion to replace more than all the blood you have in 24 hours. It happens when you've lost blood and platelets and then your blood is replaced with lots of red cells. If you have this, a doctor will decide if you need more platelets to get your count back up.

Distributional thrombocytopenia

This is the name for low platelet counts when your platelets get trapped in your spleen. Your spleen usually will have about 30% of your platelets in it. When your spleen is bigger than it should be, it can have up to 90% of your platelets.


This type isn't thrombocytopenia at all. It happens when a problem with a blood test makes it look like your platelets are low when they really aren't. It usually isn't a problem, but it could be if you get more testing or treatment you don't need.

Thrombocytopenia is often found by chance when your doctor does a routine blood test. They might ask you questions to find out why your platelet counts are low and what type of thrombocytopenia you have. 

Some questions your doctor may ask include:

  • What symptoms (including bleeding) have you noticed?
  • When did you first see them?
  • Does anything make them better? Or worse?
  • What medications and supplements are you taking?
  • Have you had any shots in the last month, a blood transfusion, or used drugs with a needle?
  • Does anyone in your family have a problem with their immune system, bleeding, or bruising?
  • What have you eaten recently?

Some tests check for low platelet counts or other things that may lead to low platelets:

  • Blood test. A complete blood count (CBC) looks at the amount of red and white blood cells and platelets in your blood.
  • Blood smear. This shows how your platelets look under a microscope.
  • Bone marrow test. Your bone marrow is where new blood cells get made. Your doctor uses a very fine needle to draw a small amount of liquid bone marrow and check it for cells that may not be working right. Or you may get a biopsy, using a different kind of needle, so your doctor can check the types and numbers of cells in the bone marrow.
  • Blood clot test. This test measures how long it takes your blood to clot. It tells you how your platelets are working.
  • Platelet antibody test. This test will see if antibodies in your blood are attacking your platelets. If you have platelet antibodies in your blood, it means your low platelets are caused by ITP.

Your doctor may do a physical exam to check you for signs of internal bleeding and feel if your spleen seems big. They may order an abdominal ultrasound to look for changes in your liver, spleen, or lymph nodes. You may also need genetic or other tests to help your doctor figure out why your platelets are low.

For most people, having a low platelet count isn't a big problem. But if you have a severe form, you can bleed even when you aren't hurt in your eyes, gums, or bladder. You also could bleed too much when you’re hurt. You could bleed even with no injury at all.Trombocytopenia can be fatal, especially if you bleed a lot or bleed in your brain.

Thrombocytopenia Complications

  • Life-threatening hemorrhageor internal bleeding. You'll get this when you have a platelet lab value under 20,000. When your platelets are this low, it can cause sudden bleeds, including brain hemorrhage, even when you don't have an injury. 
  • Strokes.  If your blood clots too much despite your low platelets, you may have a stroke. 
  • Heart attack. You can have a heart attack if low platelets causes less blood to flow to your heart.

  If you have low platelets and don't follow your doctors advice, the condition can be life-threatening.

  • What's causing the problem?
  • Do I need treatment? 
  • What are my treatment options? Which do you recommend?
  • Do these treatments have side effects? What can I do about them?
  • How will we know if the treatment is working?
  • When will I start to feel better?
  • What do you expect in my case?
  • Does this condition put me at risk for other health problems?
  • Do I need to see a specialist?
  • How will I be monitored? 
  • How do I know if my platelets drop at home or I'm bleeding internally?

There are many treatment options for thrombocytopenia. If it's mild, you might not need any treatment. You'll need to work with your doctor to weigh the pros and cons of each and find a therapy that's right for you. The treatment will depend on what type of thrombocytopenia you have and what's causing it.

If your thrombocytopenia is drug-induced, stopping your medicine may help. If you have ITP and the trouble is with your immune system, your treatment depends on how severe a case you have. If it's mild, you may only need to get regular checks of your platelet levels.

When you do need treatment, the goal is to get your platelet count up enough to prevent serious bleeding in your gut or brain. You may need a platelet transfusion if there is immediate life-threatening bleeding. You may only get treatment when you have symptoms. But it's possible your doctor could suggest treatment even when you feel fine. That's more likely if you're at high risk for bleeding or other complications.

Some treatment options for low platelets include:

  • Blood or platelet transfusions. Your doctor can give you more blood or platelets to replace those you've lost.
  • Medicines. You may need medication for thrombocytopenia if the problem is with your immune system. Steroids or other medicines that target your immune system may help to keep your antibodies from attacking your platelets. 
  • Surgery. If other options don't work, your doctor might suggest surgery to take out your spleen (splenectomy).
  • Plasma exchange. If your low platelet counts are from TTP, plasma exchange can filter out the abnormal parts of your blood to help keep you from getting clots.

You can still do most things, but you may need to make some changes to your lifestyle to avoid getting hurt or cut. These include: 

  • Avoid activities that make injury likely. Ask your doctor about steps you should take. For instance, it may be best for you to avoid contact sports such as boxing, martial arts, or football.
  • Be thoughtful about which medicines you take. You probably shouldn't take medicines that make bleeding easier, such as aspirin and ibuprofen, or other NSAIDS like naproxen or Aleve.
  • Don't drink too much alcohol. Check with your doctor to see how much it's OK to drink. It's always better to drink in moderation. Alcohol can make your body produce platelets more slowly.

Your case may be different from someone else's. Your doctor will watch you to see how you're doing. If your thrombocytopenia is mild, you may not need any treatment. But even people who do need treatment can lead full lives.

Find out as much as you can about your condition and its causes so you can best manage it.

The Platelet Disorder Support Association has information about immune thrombocytopenia and other platelet disorders. They can help you connect to doctors, support groups, and other resources.

If you have thrombocytopenia, it means your platelets are lower than they should be. Low platelet counts can happen for many reasons, and your treatment will depend on what's causing your condition and how severe it is. Most people with thrombocytopenia won't have any symptoms or serious health risks. See your doctor or a blood disorder specialist (hematologist) to find out what's causing your low platelet counts and what steps you can take to protect your health.

  • What is thrombocytopenia caused by?

Anything that leads you to have fewer platelets than you need can cause thrombocytopenia. Your immune system can cause it by attacking platelets. It's also caused a lot by medicines you're taking.

  • What is a major symptom of thrombocytopenia?

Most people with low platelet counts won't feel any different. But when your platelets are too low, you may bleed more than you should when you cut yourself. If you have a more severe case, ask your doctor what symptoms you should watch for.

  • What happens if you have thrombocytopenia?

Most people with low platelet counts will be OK even without treatment. Your thrombocytopenia may go away by itself, depending on what's causing it. Ask your doctor what tests you should get to see how severe your condition is, what's causing it, and whether treatment is needed.