Merck Manual

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Platelet Dysfunction

By

David J. Kuter

, MD, DPhil, Harvard Medical School

Last full review/revision Jul 2020| Content last modified Jul 2020
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Topic Resources

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 cells that are made in the bone marrow and circulate in the bloodstream and help blood clot.

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 Glanzmann disease, Wiskott-Aldrich syndrome, 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).

Some people can develop platelet dysfunction after cardiopulmonary bypass during open-heart surgery.

Symptoms

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.

Bleeding in the Skin

Diagnosis

  • Blood tests to measure platelet count and clotting

  • Special tests to measure platelet function and bleeding

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 other disorders or do not 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 clotting (prothrombin time [PT] and partial thromboplastin time [PTT]). These tests measure how long it takes blood to clot. In another test, called a platelet function test, a sample of blood is collected and tested to see if platelets react normally to various platelet stimulators. Abnormal platelet function tests may indicate the nature of the inherited or acquired platelet dysfunction.

Treatment

  • Stopping or avoiding drugs that cause bleeding

  • Treating the underlying associated disease, for example, dialysis for a person with kidney failure

  • Sometimes drugs or platelet transfusion

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 or a drug called desmopressin, which helps decrease bleeding.

Drugs Mentioned In This Article

Generic Name Select Brand Names
DDAVP, STIMATE
PLAVIX
No US brand name
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