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58 Cards in this Set
- Front
- Back
What are the 3 things involved in Primary Hemostasis?
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1. Vascular Wall = Endothelium and Subendothelial Collagen
2. Platelets 3. von Willebrand Factor |
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What does Primary Hemostasis involve the formation of?
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Platelet plug
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Describe the formation of a Platelet Plug
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1. Injury ➞ exposure of Subendothelial Collagen
2. vWF binds to collagen 3. Platelet binds to vWF via Gp Ib = Platelet Adhesion 4. Platelet-Platelet binding via Fibrinogen and Gp IIb/IIIa = Platelet Aggregation |
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What is Secondary Hemostasis?
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Coagulation cascade resulting in a cross-linked fibrin clot
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What comprises the Extrinsic Pathway?
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Tissue Factor (Thromboplastin)
Factor VII (7) |
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What comprises the Intrinsic Pathway?
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Prekallikrein
HMWK Factors 12, 11, 9, 8 |
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What comprises the Common pathway of coagulation?
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Factors 10, 5, 2 (Prothrombin), 1 (Fibrinogen)
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This Factor causes Fibrin stabilization by converting soluble fibrin monomers to insoluble fibrin and crosslinking fibrin
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Factor 13
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Explain how the Extrinsic Pathway can activate the Intrinsic pathway
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-Factor 7a can activate Factor 9 (which along with Factor 8a can activate Factor 10)
-When pathway is complete Thrombin can go back and activate Factor 8 (which along with Factor 9 activates Factor 10) |
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What is the most global screening test for Primary Hemostasis? Explain it
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Bleeding time = puncture the skin with a needle and measure the time it takes for bleeding to stop
-Normal values = 2-7 min |
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Describe the Platelet Function Analyzer (PFA)
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Tests Primary Hemostasis
- tests the functionalities of vWF and Platelets IN VITRO -Downfall: doesn't test the vessel wall |
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This is the test for the Extrinsic Pathway of coagulation
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Prothrombin Time (PT)
- tests factors 7, 10, 5, 2, 1 |
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This is teh test for the Intrinsic Pathway of coagulation
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Partial Thromboplastin Time (PTT)
- tests factors 12, 11, 9, 8 / 10, 5, 2, 1 |
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What is the use of PTT?
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follow patients who are taking Heparin
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What is PT used to monitor?
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Warfarin = Extrinsic Pathway
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Explain the D-dimer test
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Is a molecule that can only be formed from the degradation of cross-linked fibrin = specific for Fibrinolysis
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Explain the Fibrin Split Products (FSP) test
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detects fragments associated with plasmin degradation of Fibrinogen or Insoluble fibrin from fibrin clots = not as specific as D-dimer for detection of Fibrinolysis
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What factors does Warfarin therapy decrease the levels of?
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Factors 2, 7, 9, 10 = Vitamin K-dependent Factors
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How do you tell the difference between a Factor deficiency and the presence of an Inhibitor?
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-If you add normal plasma and a clot forms = Factor deficiency
-If you add normal plasma but a clot doesn't form = Inhibitor |
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What 2 things could causes Vasculitis and result in bleeding?
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1. Infections
- meningococcemia, Infective Endocarditis, Rickettsioses 2. Drugs |
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What 3 things could cause impaired collagen formation and a resultant bleeding disorder?
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1. Scurvy = Vitamin C deficiency, which is required for Collagen synthesis
2. Cushing syndrome = high levels of blood cortisol 3. Ehlers-Danlos Syndrome = defect in collagen synthesis |
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What immune complex hypersensitivity disease could cause bleeding?
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Henoch-Schonlein purpura
-purpuric rash -colicky abdominal pain -polyarthralgia -acute glomerulonephritis **deposition of IgA in small blood vessels |
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Explain how Hereditary Hemorrhagic Telangiectasia causes bleeding
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Autosomal dominant disorder characterized by DILATED, torturous blood vessels that have THIN walls and hence bleed
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Infiltration of blood vessels with what could cause bleeding
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Amyloid
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Define Thrombocytopenia
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decrease in the # of platelets
- normal = 150K - 400K |
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Give 7 examples that could cause decreased production of Platelets
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1. Bone Marrow Failure
2. Drugs 3. Infection (HIV) 4. Megaloblastic Anemia = Folate or B12 deficiency 5. Paroxysmal Nocturnal Hemoglobinuria = acquired membrane defect in multipotent myeloid stem cells = loss of membrane proteins that inhibit complement lysis 6. Myelodysplastic syndromes 7. Marrow Infiltration = Leukemia |
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Give 4 examples of Immunological destruction that would decrease Platelet Survivial and cause Thrombocytopenia
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1. Idiopathic Thrombocytic Purpura
2. SLE 3. Drugs -> Heparin 4. Infection (HIV) |
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Give 3 examples of nonimmunologic destruction of platelets causing Thrombocytopenia
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1. Thrombotic Thrombocytopenic Purpura
2. DIC 3. Microangiopathic Hemolytic Anemia (MAHA) |
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What organ can sequester Platelets and cause thrombocytopenia?
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Spleen
**Hypersplenism in Portal HTN |
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Describe Dilution Thrombocytopenia
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Occurs in patients who have received massive transfusions and their platelet concentration is diluted enough to allow for bleeding
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What is the cause of Idiopathic (Immune) Thrombocytopenic Purpura (ITP)?
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Autoantibodies against GP Ib or IIb/IIIa
**usually IgG |
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Describe the pathogenesis of ITP
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1. Anti-platelet Ab's
2. Platelet opsonization 3. Platelet destruction in the spleen 4. Thrombocytopenia |
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What are the lab findings in Idiopathic Thrombocytic Purpura
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1. Prolonged Bleeding time/PFA = b/c platelets are affected
2. Normal PT/PTT = coagulation is not affected |
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What are 4 pathologies associated with Idiopathic Thrombocytic Purpura?
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1. Thrombocytopenia with Megathrombocytes in peripheral blood
2. Anti-platelet Ab's 3. Splenic congestion of sinusoids and lymphoid hyperplasia 4. Increases BM Megakaryocytes |
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Describe Chronic Idiopathic Thrombocytpic Purpura
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1. Most common in WOMEN <40
2. Mucocutaneous bleeding -bleeds are in response to minor injuries |
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Describe Acute Idiopathic Thrombocytic Purpura
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Occurs in children following a Viral infection
-abrupt onset of epistasis |
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What are the treatments for Chronic Idiopathic thrombocytic purpura?
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1. Steroids
2. Immunosuppression 3. Splenectomy (chronic) **Acute ITP is usually self-limited |
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What are 4 drugs that commonly cause Drug-Induced Thrombocytopenia?
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1. Quinine = anti-malarial
2. Quinidine = antiarrhythmic agent 3. Sulfonamides 4. Heparin |
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Describe Type 1 Heparin induced thrombocytopenia
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Mild thrombocytopenia
Common = 5% of patients on heparin |
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Describe Type 2 Heparin-Induced Thrombocytopenia
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-Severe thrombocytopenia due to Ab's against Heparin-PF4 complex
-paradoxical risk of thrombosis due to platelet activation |
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What 3 diseases does Thrombotic Microangiopathy comprise?
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1. Thrombotic Thrombocytopenic Purpura
2. DIC 3. Hemolytic Uremic Syndrome |
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What is the underlying cause of Thrombotic Thrombocytopenic Purpura and Hemolytic Uremic Syndrome?
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deficiency of a vWF cleaving protease = ADAMTS 13 in TTP
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Describe the pathogenesis of TTP and HUS
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1. decreased vWF cleaving protease
2. Ultra-high molecular weight vWF multimers = spontaneously cause platelets to aggregate w/out endothelial injury 3. Platelet activation and consumption 4. Thrombocytopenia and microvascular thrombi (caused by platelet aggregates) |
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What are the pathologic findings in HUS and TTP?
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1. Thrombocytopenia = due to the consumption of platelets by Platelet aggregates caused by HMW vWF
2. Schistocytes = due to platelet aggregates in the microvasculature -> RBC's bump into them and are sheered 3. Normal PT/PTT = coagulation cascade factors are not affected |
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Describe the clinical features of Thrombotic Thrombocytopenic Purpura
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1. Adult women
2. Classic pentad -Fever -Neurologic deficits -Microangiopathic Hemolytic anemia -Thrombocytopenia -Renal Failure |
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Describe the clinical features of HUS
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1. CHILDREN (TTP = Adult women)
2. follows infection with Verotoxin producing EHEC 3. Renal failure predominates; neurologic findings absent |
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What are the major differences between HUS and TTP?
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HUS = Children with Renal Failure predominance
TTP = Adult women with neurologic deficits (along with renal failure) |
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What 2 clinical findings do HUS and TTP share?
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1. Microangiopathic Hemolytic anemia
2. Thrombocytopenia |
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What is the treatment for both HUS and TTP?
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Plasma exchange = replenishes vWF cleaving protease while taking out the HMW vWF
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This is an Autosomal Recessive deficiency of GP Ib, which causes a platelet adhesion defect = platelets do not bind to vWF
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Bernard-Soulier Syndrome
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Autosomal Recessive deficiency of GP IIb/IIIa which causes a defect in Platelet Aggregation = platelets cannot bind to eachother via fibrinogen
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Glanzmann thrombasthenia
**Glanzmann - aGGregation |
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What are the lab findings in both Bernard-Soulier syndrome and Glanzmann Thrombasthenia?
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1. Prolonged Bleeding Time / PFA
2. Normal PT/PTT |
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What is the treatment for Bernard-Soulier syndrome and Glanzmann Thrombasthenia?
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Platelet transfusion
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What are 2 acquired disorders that can lead to platelet disorders and bleeding?
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1. Aspirin and other NSAIDS = COX inhibition and suppression of PG synthesis = inhibits TXA2 synthesis
2. Uremia = renal failure resulting in increased blood urea --> somehow affects platelets |
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Immune Thrombocytopenic Purpura
- autoAb's to Gp Ib or IIb/IIIa - Megathrombocyte seen in Blood Smear due to leakage from the BM |
What platelet disorder would cause this?
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Draw the Coagulation Cascade
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-
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HUS or TTP
-Schistocytes due to platelet consumption and intravascular thrombosis = RBC's are sheered by the platelet plugs |
What platelet disorder would cause this?
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A 32-year-old woman is brought to the emergency room by a friend b/c of the onset of confusion and disorientation over the past day. Upon physical exam, you discover generalized rash, fever, and bilateral Babinski sign. You immediately order several blood tests, which show an elevated LDH, increased indirect bilirubin, thrombocytopenia, and anemia. Examination of a peripheral blood smear yields multiple reticulocytes and schistocytes.
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Thrombotic Thrombocytopenic Purpura
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