16 Questions
What is thrombocytopenia characterized by?
A reduction in platelet number
What is the main mechanism of drug-induced immune thrombocytopenia?
Immune complex-mediated platelet destruction
What is the typical time frame for the onset of thrombocytopenia in people with drug-associated thrombocytopenia?
2-3 days
What percentage of people treated with heparin develop a mild, transient thrombocytopenia?
50%
What is the primary cause of heparin-induced thrombocytopenia (HIT)?
Immune reaction against platelet factor 4-heparin complex
What is the primary treatment for heparin-induced thrombocytopenia (HIT)?
Immediate discontinuation of heparin therapy
What is the consequence of the immune complexes formed in HIT?
Platelet activation and thrombosis
What is the result of the activation of platelets in HIT?
Prothrombotic platelet particles and induction of TF
What is the primary cause of platelet destruction in primary ITP?
Immune system directly destroying platelets
What is the typical platelet count in ITP?
Less than 100,000 mL
What is the age group with the highest incidence of primary ITP?
Older adults above 60 years
What is the classification of primary ITP based on duration?
Newly diagnosed, persistent, and chronic
What is a common symptom of ITP?
Bruising and bleeding from the gums
What is the site of platelet destruction in ITP?
Spleen
What is the inheritance pattern of the familial form of TTP?
Autosomal recessive
When can the acquired form of TTP occur?
Only in late childhood or adulthood
Study Notes
Thrombocytopenia
- Thrombocytopenia is a reduction in platelet number, which can result from: • Decreased platelet production • Increased sequestration of platelets in the spleen • Destruction of platelets by antibodies • Depletion of platelets due to thrombi • Dilution of blood through multiple transfusions • Decreased platelet survival
Drug-Induced Thrombocytopenia
- Some drugs, such as aspirin, atorvastatin, and some antibiotics, can cause drug-induced immune thrombocytopenia
- These drugs induce an antigen-antibody response and formation of immune complexes, leading to platelet destruction by complement-mediated lysis
- Drug-associated thrombocytopenia is characterized by: • Rapid fall in platelet count within 2 to 3 days of resuming a drug or 7 or more days after starting a drug for the first time • Rapid rise in platelet count after the drug is discontinued
Heparin-Induced Thrombocytopenia (HIT)
- HIT is associated with the anticoagulant drug heparin
- 50% of people treated with heparin develop a mild, transient thrombocytopenia within 2 to 5 days of starting the drug
- Approximately 1% to 5% of people treated with heparin experience life-threatening thromboembolic events 1 to 2 weeks after the start of therapy
- HIT is caused by an immune reaction directed against a complex of heparin and platelet factor 4
- Treatment of HIT requires the immediate discontinuation of heparin therapy
Immune Thrombocytopenic Purpura (ITP)
- ITP is an isolated thrombocytopenia with a platelet count of less than 100,000 mL
- Characterized by: • Purpuric rash • Normal white blood cells • Normal hemoglobin
- ITP results in platelet antibody formation and excess destruction of platelets
- Primary ITP: • Affects both children and adults • Highest incidence in people older than 60 years • Classified as: • Newly diagnosed (from diagnosis until 3 months) • Persistent (from diagnosis until 3 to 12 months) • Chronic (from diagnosis until >12 months)
- Secondary ITP: • Associated with autoimmune disorders and chronic infections such as: • Helicobacter pylori • Hepatitis C virus • Epstein-Barr virus • HIV • Clinical manifestations include: • A history of bruising, bleeding from the gums, epistaxis, melena, and abnormal menstrual bleeding • Splenic enlargement may occur • Condition may be discovered incidentally or as a result of signs of bleeding
Thrombotic Thrombocytopenic Purpura (TTP)
- Familial form: • Autosomal recessive inheritance • Rare, appearing in infancy and early childhood • Symptoms occur regularly and exacerbate with stress
- Acquired form: • Not inherited • More common, occurring in late childhood or into adulthood • May be a single occurrence or many occurrences over time
This quiz covers bleeding disorders associated with platelet disorders, including thrombocytopenia and drug-induced thrombocytopenia. Learn about the causes and effects of platelet disorders.
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