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58 Cards in this Set

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What are the 3 things involved in Primary Hemostasis?
1. Vascular Wall = Endothelium and Subendothelial Collagen
2. Platelets
3. von Willebrand Factor
What does Primary Hemostasis involve the formation of?
Platelet plug
Describe the formation of a Platelet Plug
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
What is Secondary Hemostasis?
Coagulation cascade resulting in a cross-linked fibrin clot
What comprises the Extrinsic Pathway?
Tissue Factor (Thromboplastin)

Factor VII (7)
What comprises the Intrinsic Pathway?
Prekallikrein
HMWK
Factors 12, 11, 9, 8
What comprises the Common pathway of coagulation?
Factors 10, 5, 2 (Prothrombin), 1 (Fibrinogen)
This Factor causes Fibrin stabilization by converting soluble fibrin monomers to insoluble fibrin and crosslinking fibrin
Factor 13
Explain how the Extrinsic Pathway can activate the Intrinsic pathway
-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)
What is the most global screening test for Primary Hemostasis? Explain it
Bleeding time = puncture the skin with a needle and measure the time it takes for bleeding to stop
-Normal values = 2-7 min
Describe the Platelet Function Analyzer (PFA)
Tests Primary Hemostasis
- tests the functionalities of vWF and Platelets IN VITRO
-Downfall: doesn't test the vessel wall
This is the test for the Extrinsic Pathway of coagulation
Prothrombin Time (PT)
- tests factors 7, 10, 5, 2, 1
This is teh test for the Intrinsic Pathway of coagulation
Partial Thromboplastin Time (PTT)
- tests factors 12, 11, 9, 8 / 10, 5, 2, 1
What is the use of PTT?
follow patients who are taking Heparin
What is PT used to monitor?
Warfarin = Extrinsic Pathway
Explain the D-dimer test
Is a molecule that can only be formed from the degradation of cross-linked fibrin = specific for Fibrinolysis
Explain the Fibrin Split Products (FSP) test
detects fragments associated with plasmin degradation of Fibrinogen or Insoluble fibrin from fibrin clots = not as specific as D-dimer for detection of Fibrinolysis
What factors does Warfarin therapy decrease the levels of?
Factors 2, 7, 9, 10 = Vitamin K-dependent Factors
How do you tell the difference between a Factor deficiency and the presence of an Inhibitor?
-If you add normal plasma and a clot forms = Factor deficiency

-If you add normal plasma but a clot doesn't form = Inhibitor
What 2 things could causes Vasculitis and result in bleeding?
1. Infections
- meningococcemia, Infective Endocarditis, Rickettsioses

2. Drugs
What 3 things could cause impaired collagen formation and a resultant bleeding disorder?
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
What immune complex hypersensitivity disease could cause bleeding?
Henoch-Schonlein purpura
-purpuric rash
-colicky abdominal pain
-polyarthralgia
-acute glomerulonephritis

**deposition of IgA in small blood vessels
Explain how Hereditary Hemorrhagic Telangiectasia causes bleeding
Autosomal dominant disorder characterized by DILATED, torturous blood vessels that have THIN walls and hence bleed
Infiltration of blood vessels with what could cause bleeding
Amyloid
Define Thrombocytopenia
decrease in the # of platelets
- normal = 150K - 400K
Give 7 examples that could cause decreased production of Platelets
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
Give 4 examples of Immunological destruction that would decrease Platelet Survivial and cause Thrombocytopenia
1. Idiopathic Thrombocytic Purpura
2. SLE
3. Drugs -> Heparin
4. Infection (HIV)
Give 3 examples of nonimmunologic destruction of platelets causing Thrombocytopenia
1. Thrombotic Thrombocytopenic Purpura
2. DIC
3. Microangiopathic Hemolytic Anemia (MAHA)
What organ can sequester Platelets and cause thrombocytopenia?
Spleen

**Hypersplenism in Portal HTN
Describe Dilution Thrombocytopenia
Occurs in patients who have received massive transfusions and their platelet concentration is diluted enough to allow for bleeding
What is the cause of Idiopathic (Immune) Thrombocytopenic Purpura (ITP)?
Autoantibodies against GP Ib or IIb/IIIa

**usually IgG
Describe the pathogenesis of ITP
1. Anti-platelet Ab's
2. Platelet opsonization
3. Platelet destruction in the spleen
4. Thrombocytopenia
What are the lab findings in Idiopathic Thrombocytic Purpura
1. Prolonged Bleeding time/PFA = b/c platelets are affected

2. Normal PT/PTT = coagulation is not affected
What are 4 pathologies associated with Idiopathic Thrombocytic Purpura?
1. Thrombocytopenia with Megathrombocytes in peripheral blood
2. Anti-platelet Ab's
3. Splenic congestion of sinusoids and lymphoid hyperplasia
4. Increases BM Megakaryocytes
Describe Chronic Idiopathic Thrombocytpic Purpura
1. Most common in WOMEN <40
2. Mucocutaneous bleeding
-bleeds are in response to minor injuries
Describe Acute Idiopathic Thrombocytic Purpura
Occurs in children following a Viral infection
-abrupt onset of epistasis
What are the treatments for Chronic Idiopathic thrombocytic purpura?
1. Steroids
2. Immunosuppression
3. Splenectomy (chronic)

**Acute ITP is usually self-limited
What are 4 drugs that commonly cause Drug-Induced Thrombocytopenia?
1. Quinine = anti-malarial
2. Quinidine = antiarrhythmic agent
3. Sulfonamides
4. Heparin
Describe Type 1 Heparin induced thrombocytopenia
Mild thrombocytopenia
Common = 5% of patients on heparin
Describe Type 2 Heparin-Induced Thrombocytopenia
-Severe thrombocytopenia due to Ab's against Heparin-PF4 complex
-paradoxical risk of thrombosis due to platelet activation
What 3 diseases does Thrombotic Microangiopathy comprise?
1. Thrombotic Thrombocytopenic Purpura
2. DIC
3. Hemolytic Uremic Syndrome
What is the underlying cause of Thrombotic Thrombocytopenic Purpura and Hemolytic Uremic Syndrome?
deficiency of a vWF cleaving protease = ADAMTS 13 in TTP
Describe the pathogenesis of TTP and HUS
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)
What are the pathologic findings in HUS and TTP?
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
Describe the clinical features of Thrombotic Thrombocytopenic Purpura
1. Adult women
2. Classic pentad
-Fever
-Neurologic deficits
-Microangiopathic Hemolytic anemia
-Thrombocytopenia
-Renal Failure
Describe the clinical features of HUS
1. CHILDREN (TTP = Adult women)
2. follows infection with Verotoxin producing EHEC
3. Renal failure predominates; neurologic findings absent
What are the major differences between HUS and TTP?
HUS = Children with Renal Failure predominance

TTP = Adult women with neurologic deficits (along with renal failure)
What 2 clinical findings do HUS and TTP share?
1. Microangiopathic Hemolytic anemia
2. Thrombocytopenia
What is the treatment for both HUS and TTP?
Plasma exchange = replenishes vWF cleaving protease while taking out the HMW vWF
This is an Autosomal Recessive deficiency of GP Ib, which causes a platelet adhesion defect = platelets do not bind to vWF
Bernard-Soulier Syndrome
Autosomal Recessive deficiency of GP IIb/IIIa which causes a defect in Platelet Aggregation = platelets cannot bind to eachother via fibrinogen
Glanzmann thrombasthenia

**Glanzmann - aGGregation
What are the lab findings in both Bernard-Soulier syndrome and Glanzmann Thrombasthenia?
1. Prolonged Bleeding Time / PFA

2. Normal PT/PTT
What is the treatment for Bernard-Soulier syndrome and Glanzmann Thrombasthenia?
Platelet transfusion
What are 2 acquired disorders that can lead to platelet disorders and bleeding?
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
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?
Draw the Coagulation Cascade
-
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?
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.
Thrombotic Thrombocytopenic Purpura