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56 Cards in this Set
- Front
- Back
What is it called when there are too FEW platelets? Cuses?
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Thrombocytopenia
Decreased production Increased degradation |
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What is it called when there are too many platelets?
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Thrombocytosis
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How are platelets produced from megakaryocytes?
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Budding
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What's the lifespan of a platelet?
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5-9 days
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What is the normal platelet count?
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150-400E9/L
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What protein regulates platelet production?
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Thrombopoietin
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What organs recycle platelets?
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Spleen
Liver |
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What cells in the liver destroy platelets?
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Kupffer cells
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What is a storage site for platelets?
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Spleen
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What causes platelets to be released by the spleen?
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Sympathetic activation
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What levels of platelets are associated with increased risk of spontaneous hemorrhage? Spontaneous intracranial hemorrhage?
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Spontaneous: <20,000
Intracranial: <10,000 |
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What is the platelet cutoff for general surgery?
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60,000/uL
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What are some causes of prolonged bleeding in the context of a normal platelet count?
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Asprin (think decreased thromboxane-->decreased activation )
Uremia (altered prostaglandins/thromboxane-->decreased activation) von Willebrand |
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What are some causes of decreased production of platelets?
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Bone marrow problems!
-Primary failure -Invasion of the marrow -Injury to bone marrow -Nutritional problems -Megaloblastic anemia -Hereditary platelet disorders |
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What is the effect of alcohol on bone marrow?
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Inhibition
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What are the causes of increased platelet destruction?
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Immune mediated
Non-immune mediated |
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What are some of the non immune-mediated causes of platelet destruction?
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DIC
TTP Hypersplenism |
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What is the effect of having a large spleen on blood platelet levels?
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Sucks up the platelets from the circulation
Can get levels as low as 40,000-60,000 |
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What are some of the immune mediated causes of increased platelet destruction?
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Immune thrombocytopenia
Neonatal autoimmune thrombocytopenia Drug induced Heparin induced |
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What are the different types of autoimmune thrombocytopenia?
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Acute
Chronic Secondary |
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Who gets acute autoimmune thrombocytopenia?
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Children
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What are the symptoms of acute autoimmmune thrombocytopenia?
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Viral illness 3 weeks ago
Severe bleeding symptoms; self limited |
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Who gets chronic autoimmmune thrombocytopenia?
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Women
20-40 |
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What does the bone marrow look like in chronic autoimmmune thrombocytopenia?
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Normal
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What diseases is secondary autoimmmune thrombocytopenia associated with?
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Disordered lymphoid function:
SLE Lymphoma CLL |
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What is a good therapy for ITP?
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Splenectomy!
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What are some concerns for splenecomy in people with ITP?
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Are the antibodies produced in the marrow?
It could be the case that the platelets are destroyed somewhere else |
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Other than splenectomy, what are some of the other therapies for ITP?
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IVIg
Anti CD 20 immunotherapy Immune modulators Platelet growth factors |
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What is the cause of neonatal allo immune thrombocytopenia?
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Antibodies from mom are put into the circulation of the baby
It can be when there's a mismatch in an antigen status: mom is Pla1- and the fetus is Pla1+ |
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What's the timeline for platelet levels to recover after a drug-induced thrombocytopenia?
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7 days - 3 weeks
YOu need to wait until all of the drug is out of the body |
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What are the two forms of heparin induced thrombocytopenia?
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Mild
Severe: -Platelet count decreases more than 30% form baseline |
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What's the treatment for heparin induced thrombocytopenia?
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Treat the thrombosis!
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What's the mechanism of heparin induced thrombocytopenia?
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1. Heparin comes into body
2. Heparin PF4 complexes form 3. Antibodies that bind to the platelets also bind to the heparin-PF4 complexes cause more activation of platelets 4. More release of PF4 (it becomes a cycle, here) 5. Endothelial cell injruy |
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How long do antibodies in heparin induced thrombocytopenia stick around?
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3 months!
Beware! |
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What are the causes of primary thrombocytosis?
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Clonal myeloproliferative disorders
-Chronic myelogenous leukemia -Essential thrombocytosis -Polycythemia vera |
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Why is there often bleeding in the setting of primary thrombocytosis?
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It's often the case that despite their large numbers, the platelets are still dysfunctional
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What levels is defined as secondary thrombocytosis?
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>700,000/uL
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What are causes of secondary thrombocytosis?
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Inflammation
Hemorrhage Post splenectomy Iron deficiency |
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What are some ways that you can assess platelet function?
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Peripheral smears
Counts: NL = 150k - 450k Bleeding time: NL < 9 minutes Platelet aggregation: main tool |
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What are some different substances you can use to assess platelet aggregation?
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Thrombin
ADP Epinephrine Collagen |
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What are the properties of the qualitative platelet disorders?
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Platelet function abnormalities
Normal count Bleeding symptoms |
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What are the receptors that cause interplatelet links?
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GPIIb
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What molecules cause the release reaction in platelets?
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Thromboxane
This is blocked with asprin! |
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What are the different kinds of inherited disorders of platelet function?
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Platelet-vessel
Platelet-platelet Granules, secretion, signal transduction |
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What are the congenital disorders of adhesion?
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Von Willebrand's disease
Bernard soulier syndrome |
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What defect is present in vWD?
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Missing a linker molecule between the platelet and the vascular endothelium
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What defect is present in Bernard Soulier?
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GpIb defect
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What are the findings in Bernard Soulier Syndrome?
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Thrombocytopenia
Giant platelets found on the smear |
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What platelet aggravating factor won't vWD or Bernard Soulier patients respond to?
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Ristocetin
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What is afibrinogemia?
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Platelet and coagulation factor defect type bleeding
Fibrin just isn't there |
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What protein is mutated in Glanzmann's thrombocytopenia?
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Autosomal disorder
Absent/defective GpIIbIIIa |
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If you have thrombasthenia/afibrinogenemia, what platelet aggravants aren't effective?
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ADP
Epinephrine |
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What are the different kinds of disorders of activation and secretion of platelets?
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Storage pool deficiency
Defectsin platelet stimulus response coupling pathways Primary secretion defects |
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What is the difference between the aggravation patterns between Glanzmann's and Bernard-Soulier?
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They're the opposite!
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What are the different kinds of acquired platelet function defects?
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Urmia
Myeloproliferative disorders Myeodysplastic disorders, leukemia Dysproteinemias Cardiopulmonary bypass Antibodies Lung disease Drugs |
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How does uremia cause an acquired platelet function defect?
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Toxins in the wall cause abnormalities in the wall, abnoramlities in the platelet prostaglandin pathways
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