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Platelet Dysfunction

By David J. Kuter, MD, DPhil, Professor of Medicine; Chief of Hematology, Harvard Medical School; Massachusetts General Hospital

Platelet dysfunction may be due to a problem in the platelets themselves or to an external factor that alters the function of normal platelets.

Platelets are cell fragments that circulate in the bloodstream and help blood clot (see also Overview of Platelet Disorders).

When platelets do not function properly, people are at risk of excessive bleeding due to injuries or even spontaneous bleeding. Platelet dysfunction may be

  • Inherited

  • Acquired

Inherited platelet disorders

Von Willebrand disease is the most common inherited platelet-related disorder. There are a number of other rare inherited disorders that affect platelets, including Chédiak-Higashi syndrome and Bernard-Soulier syndrome.

Acquired platelet disorders

Acquired platelet disorders are usually caused by certain

  • Drugs

  • Diseases

The most common drugs that affect platelet function are aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), along with antiplatelet drugs such as clopidogrel and similar drugs that are used to prevent strokes and heart attacks.

Diseases that can affect platelet function include cirrhosis, multiple myeloma, kidney disease, and systemic lupus erythematosus (lupus).


Symptoms depend on the cause and severity of platelet dysfunction.

People with inherited disorders of platelet dysfunction may have a lifelong history of easy bruising or excessive bleeding after minor injuries or minor surgery such as dental extractions. Boys may have had excessive bleeding after circumcision. Sometimes the first sign in women is that their menstrual periods are very heavy.

Other symptoms of platelet disorders include tiny red dots (petechiae) on the skin and bruising after minor injuries.


  • Blood tests

Doctors suspect a drug is causing platelet dysfunction if symptoms begin after a person starts taking that drug. Doctors suspect an inherited cause if symptoms begin early in life in people who do not have any disorders or take any drugs that cause platelet dysfunction.

Doctors first do a complete blood count (CBC) to measure the number of platelets and see whether the person's symptoms are caused by a low number of platelets (thrombocytopenia). If the number of platelets is normal, doctors suspect there may be platelet dysfunction. If the cause is not clear, doctors may need to do blood tests to measure substances that are involved in platelet activation and clotting.


  • Stopping or avoiding drugs that cause bleeding

If platelet dysfunction is caused by a drug, stopping the drug usually is the only treatment needed. People with an inherited platelet disorder that causes excessive bleeding usually should not take drugs that impair platelet function. When people with an inherited platelet dysfunction have serious bleeding, they may need a platelet transfusion.