(See also Overview of Platelet Disorders Overview of Platelet Disorders Platelets (sometimes called thrombocytes) are cell fragments produced in the bone marrow that circulate in the bloodstream and help blood to clot. Thrombopoietin, primarily produced in the liver... read more 
and Overview of Thrombocytopenia Overview of Thrombocytopenia Thrombocytopenia is a low number of platelets (thrombocytes) in the blood, which increases the risk of bleeding. Thrombocytopenia occurs when the bone marrow makes too few platelets or when... read more .)
Platelets are cells that are made in the bone marrow and circulate in the bloodstream and help blood clot How Blood Clots Hemostasis is the body's way of stopping injured blood vessels from bleeding. Hemostasis includes clotting of the blood. Too little clotting can cause excessive bleeding from minor injury Too... read more .
When platelets do not function properly, people are at risk of excessive bleeding Bruising and Bleeding Bruising or bleeding after an injury is normal (see also How Blood Clots). However, some people have disorders that cause them to bruise or bleed too easily. Sometimes people bleed without any... read more 
due to injuries or even spontaneous bleeding. Platelet dysfunction may be
Inherited
Acquired
Inherited platelet disorders
Von Willebrand disease Von Willebrand Disease Von Willebrand disease is a hereditary deficiency or abnormality of the blood protein von Willebrand factor, which affects platelet function, causing excessive bleeding. (See also Overview of... read more 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 Wiskott-Aldrich Syndrome Wiskott-Aldrich syndrome is a hereditary immunodeficiency disorder characterized by abnormal antibody (immunoglobulin) production, T-cell (lymphocyte) malfunction, a low platelet count, and... read more , Chédiak-Higashi syndrome, Chédiak-Higashi Syndrome Chédiak-Higashi syndrome is a very rare hereditary immunodeficiency disorder characterized by recurrent bacterial respiratory and other infections and lack of pigment in the hair, eyes, and... read more and Bernard-Soulier syndrome. Some of these syndromes include skin disorders, abnormalities in immune function, and reduced kidney function.
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 Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more 
, multiple myeloma Multiple Myeloma Multiple myeloma is a cancer of plasma cells in which abnormal plasma cells multiply uncontrollably in the bone marrow and occasionally in other parts of the body. People often have bone pain... read more , kidney disease Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more , and systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more 
(lupus).
Some people can develop platelet dysfunction after cardiopulmonary bypass during open-heart surgery.
Symptoms of Platelet Dysfunction
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.
Ecchymoses are large purple bruises seen here on the leg.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Petechiae are small red, purple, or brown spots as seen here in the skin.
By permission of the publisher. From Deitcher S. In Atlas of Clinical Hematology. Edited by JO Armitage. Philadelphia, Current Medicine, 2004.
Petechiae are small red spots as seen here in the mouth.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Diagnosis of Platelet Dysfunction
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 Complete blood count Doctors select tests to help diagnose blood disorders based on the person's symptoms and the results of the physical examination. Sometimes a blood disorder causes no symptoms but is discovered... read more (CBC) to measure the number of platelets and see whether the person's symptoms are caused by a low number of platelets (thrombocytopenia Overview of Thrombocytopenia Thrombocytopenia is a low number of platelets (thrombocytes) in the blood, which increases the risk of bleeding. Thrombocytopenia occurs when the bone marrow makes too few platelets or when... read more ). 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 other 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 other tests, called platelet function tests, 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 of Platelet Dysfunction
Stopping or avoiding drugs that cause bleeding
Treating the underlying associated disease, for example, dialysis Dialysis Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly. There are a number of reasons... read more
for a person with kidney failureSometimes 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. Bleeding with minor procedures or with menstruation may be prevented by another medication, tranexamic acid, which improves how well the blood clots.
