Platelet Disorders
Platelet Disorders

Platelet Disorders Causes and Risk Factors

Platelet disorders happen when:

  • Your body makes too many platelets
  • Your body makes too few platelets
  • Your platelets are used up or destroyed faster than they can be replaced
  • You have enough platelets but they aren’t working properly.

Your body needs platelets to form blood clots. Blood clots help prevent you from losing too much blood after an injury.  

How does blood clot?

When a blood vessel is injured, the damaged cells in the vessel wall send out chemical signals. These signals cause clots that slow or stop bleeding.

A blood clot forms through several steps.

  1. Your blood vessel narrows. First, chemical signals cause the injured vessels to narrow to prevent more blood from leaking out.

  2. Platelets come to the site of injury. When you have a severe injury that is bleeding, chemical signals travel through your blood to the spleen, where many platelets are stored. The signals tell your spleen to release the platelets into your blood. Back at the injury site, the vessel walls become sticky and capture the platelets as they float past.

  3. A platelet plug forms. The platelets change shape and become stickier. This allows them to attach to the vessel wall and clump together into a plug.

  4. The clot forms. The platelets and other proteins in the blood called clotting factors form a blood clot. The clot contracts to pull the two sides of the damaged vessel closer together, so it is easier to repair.

If you have a high platelet count, blood clots may form often in your blood vessels. These clots can block blood flow through your body and prevent your organs from getting enough blood. If you have a low platelet count, your blood may not clot normally. You may have trouble stopping bleeding. This can make you lose a lot of blood even from a small injury.

Bleeding disorders and blood clotting disorders also can affect how blood clots form in your body.

Learn more about blood clots, what causes them, and how they can affect your health in this NIH article.


When there is an injury that causes bleeding, the nearby blood vessels constrict (narrow) to help prevent blood loss. Platelets arrive and plug the leak. The platelets also create a reaction with clotting factors that react to form a fibrin clot. Medical Animation Copyright ©️ 2022 Nucleus Medical Media, All rights reserved.

What causes platelet disorders?

Platelet disorders are caused by factors that affect how your body makes platelets. Some factors can also cause your immune system to destroy your platelets. Some people are born with a platelet disorder, while others develop it later in life.

What raises the risk of a platelet disorder?

You may have an increased risk for a platelet disorder because of your age, family history and genetics , lifestyle habits, medicines, other medical conditions, race and ethnicity, or sex.


You may be at higher risk for a platelet disorder depending on your age.

Family history and genetics

You may have a higher risk of having a platelet disorder if you have mutations , or changes, in the genes that control how your body makes platelets. You may be born with these mutations, or they may happen later in life.

If a family member has a platelet disorder or another condition that occurs when the bone marrow makes too many cells, you may have a higher risk of developing a platelet disorder.

Lifestyle habits

Your lifestyle habits can raise your risk of a low platelet count.

  • Alcohol can damage your bone marrow and cause it to make fewer platelets than normal.
  • Certain foods or herbs may raise your risk of low platelet counts. These include English walnuts and sesame seeds.
  • Using tobacco products may cause your body to make fewer platelets than normal.


Many common medicines, such as over-the-counter pain medicine or antibiotics that you may take for an infection, may increase your risk of developing a platelet disorder, especially if you have a family history or other risk factors.

Other medicines that can raise your risk include:   

  • Blood thinners, such as heparin
  • Certain antibiotics, such as ampicillin and vancomycin
  • Chemotherapy or radiation for cancer treatment
  • Immunosuppressors, such as tacrolimus and cyclosporine, that may be used after an organ transplant
  • Quinine
  • Seizure medicines, such as carbamazepine and valproic acid
  • Stomach acid (H2) blockers, such as cimetidine and ranitidine
  • Vaccines, including measles-mumps-rubella (MMR) and, less commonly, influenza and human papillomavirus (HPV)

Medical conditions

 Conditions that can raise your risk of high platelet disorders include:  


Many platelet disorders are more common in women in most age groups.

Research for your health

The research we support on blood disorders has led to more and better treatment options to improve the health of people who have platelet disorders. Through our current research, we hope to better understand the factors that cause blood disorders.

Join a clinical trial 

We lead or sponsor many studies on platelet disorders. Find clinical trials that are testing new ways to treat platelet disorders. 

Can platelet disorders be prevented?

Currently, there is no way to prevent a platelet disorder that is caused by your genes. If you plan to have children and know your child is at risk of having a platelet disorder, you can talk to a genetic counselor. A genetic counselor can answer questions about the risk and explain what choices are available.

Many platelet disorders are caused by other medical conditions or medicines. These cannot be prevented or avoided completely.

You can take the following steps to lower your risk of a platelet disorder.

  • Adopt healthy lifestyle habits. Healthy habits, such as quitting smoking and not drinking too much alcohol, may help you prevent a low platelet count.
  • Avoid certain medicines. If you have a history of platelet disorders caused by a medicine (such as one listed above), your provider may ask you to avoid these medicines.
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