Platelet function disorders
Platelet function disorders are similar to thrombocytopenia but result from platelet dysfunction rather than platelet deficiency. They characteristically cause defects in platelet adhesion or procoagulation activity (ability to bind coagulation factors to their surface to form a stable fibrin clot). Such disorders may also create defects in platelet aggregation and thromboxane A2 and may produce abnormalities by preventing the release of adenosine diphosphate (defective platelet release reaction). The prognosis varies widely.
Causes
Abnormal platelet function disorders may be inherited (autosomal recessive) or acquired. Inherited disorders cause bone marrow production of platelets that are ineffective in the clotting mechanism. Acquired disorders result from the effects of such drugs as aspirin or carbenicillin; from such systemic diseases as uremia; or from other hematologic disorders.
Signs and symptoms
Generally, the sudden appearance of petechiae or purpura or excessive bruising and bleeding of the nose and gums are the first overt signs of platelet function disorders. More serious signs are external hemorrhage, internal hemorrhage into the muscles and visceral organs, or excessive bleeding during surgery.
Diagnosis
Prolonged bleeding time in a patient with both a normal platelet count and normal clotting factors suggests this diagnosis. Determination of the defective mechanism requires a blood film and a platelet function test to measure platelet release reaction and aggregation. Depending on the type of platelet dysfunction, some or all of the test results may be abnormal.
Other typical laboratory findings are poor clot retraction and decreased prothrombin conversion. Baseline testing includes complete blood count and differential and appropriate tests to determine hemorrhage sites. In platelet function disorders, plasma clotting factors, platelet counts, prothrombin and partial thromboplastin levels, and thrombin times are usually normal.
Treatment
Platelet replacement is the only satisfactory treatment for inherited platelet dysfunction. However, acquired platelet function disorders respond to adequate treatment of the underlying disease or discontinuation of damaging drug therapy. Plasmapheresis effectively controls bleeding caused by a plasma element that’s inhibiting platelet function. During this procedure, one or more units of whole blood are removed from the patient; the plasma is removed from the whole blood, and the remaining packed red blood cells are reinfused. (See Facts about platelet concentrate.)
Special considerations
❑ Obtain an accurate patient history, including onset of bleeding, use of drugs (especially aspirin), and family history of bleeding disorders.
❑ Watch closely for bleeding from skin, nose, gums, GI tract, or an injury site.
❑ Help the patient avoid unnecessary trauma. Advise him to tell his dentist about this condition before undergoing oral surgery. (Also stress the need for good oral hygiene to help prevent the need for such surgery.)
❑ Alert other care team members to the patient’s hemorrhagic potential, especially before he undergoes diagnostic tests or surgery that may cause trauma and bleeding.
❑ Observe the patient undergoing plasmapheresis for hypovolemia, hypotension, tachycardia, and other signs of volume depletion.
❑ If platelet dysfunction is inherited, help the patient and his family understand and accept the disorder’s nature. Teach them how to manage potential bleeding episodes. Warn them that petechiae, ecchymoses, and bleeding from the nose, gums, and GI tract signal abnormal bleeding and should be reported immediately.
❑ Tell the patient with a known coagulopathy or hepatic disease to avoid aspirin, aspirin compounds, and other agents that impair coagulation.
❑ Advise the patient to wear a medical identification bracelet or to carry a card identifying him as a potential bleeder.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
Other Book Chapters Related to Clotting symptoms
Read excerpts from these other book chapters related to Clotting symptoms:
Medical Books Excerpts
- Purpura
- "In a Page: Signs and Symptoms" (2004)
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- Purpura
- "In A Page: Pediatric Signs and Symptoms" (2007)
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- Purpura
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
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- Hemophilia
- "Professional Guide to Diseases (Eighth Edition)" (2005)
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- Purpura
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
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- Thrombocytopenia
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
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- Purpura
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
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- Purpura
- "Nursing: Interpreting Signs and Symptoms" (2007)
- [ read ]
Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Clotting symptoms
» Next page: Allergic purpuras (Professional Guide to Diseases (Eighth Edition))
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