Hematology - Levine Hemostasis SG Flashcards
What are the two key cellular players in primary hemostasis:
Endothelial cells and platelets
What is the end result of primary hemostasis?
The formation of a platelet plug
What are some clinical signs that you would you expect if a patient had a defect in primary hemostasis?
Petechiae, ecchymoses, epistaxis, hemoptysis, hematuria, hematemesis, melena, hematochezia, ocular bleeding, and CNS bleeding
What are 4 main abnormalities that can lead to defective primary hemostasis?
Thrombocytopenia
Impaired platelet function
Von Willebrand factor deficiency
Impaired Von Willebrand function
What is the most common acquired disorder of primary hemostasis?
Thrombocytopenia
What is the most common hereditary disorder of primary hemostasis?
Von Willebrand factor deficiency
List 4 possible causes of a prolonged BMBT.
Thrombocytopenic
Thrombopathic (platelets don’t work)
vWF deficient/abnormal
Abnormal vasculature
What 3 tests would you want to perform to rule out secondary triggers of ITP?
Tick panel, imaging, and thorough drug history
Explain how vincristine works to treat ITP:
It prevents microtubule polymerization
It promotes accelerated megakaryocyte fragmentation and platelet release from bone marrow
True or False: Vincristine is an effective treatment for IMHA.
False
Explain the basic idea behind IVIG therapy for ITP:
It blocks mononuclear phagocyte Fc receptor so that macrophages cannot engulf Ab coated platelets
What are three blood products that contain platelets?
Fresh whole blood, platelet rich plasma, and fresh platelet concentrate
What are three indications for a platelet transfusion?
Severe thrombocytopenia
Suspect pulmonary or CNS hemorrhage
Acquired or hereditary thrombopathias
When would you give a platelet product transfusion to a dog with a platelet function problem (thrombopathia) that is not actively bleeding?
If they are going to surgery
How does Clopidogrel (Plavix) work?
Inhibiting the platelet ADP receptor
What cell surface is coagulation initiated on?
Fibroblast
What cell surface is coagulation amplified and propagated on?
Platelets
Give an example of one factor deficiency that is better represented by the cell-based model of coagulation than the traditional cascade/waterfall coagulation model and briefly explain why.
Hemophilia A because it better explains what is going on in the body
The traditional cascade/waterfall coagulation model helps better to determine laboratory testing and what is happening in the test tube
What is the target of tissue factor pathway inhibitor?
TF-FVIIa
What is the target of antithrombin?
Thrombin, Factor Xa
What is the target of protein C?
Factors V and VIII
What are the two main factors/cofactors in the extrinsic pathway?
TV and VIIa
If you have a delay in aPTT, but normal PT, what factors could be deficient?
Factos VIII, IX, XI, and XII
What is the end result of the common coagulation pathway?
fibrin formation
Spud, one of your favorite patients has Hemophilia A. If Spud were to bleed, which of the following signs would not be expected?
- Petechiae
- Joint bleed
- Hemoabdomen
- Hemothorax
- Large ecchymoses
a. Petechiae
Petechiae is associated with primary hemostasis. Hemophilia A is a disorder of coagulation factors which are associated with secondary hemostasis
What inhibitor does heparin work with to inhibit secondary hemostasis and what clotting factors does it inhibit?
Inhibitor: Antithrombin
Clotting factor: Factor II
Clotting factor: Factor Xa
Name two diseases where you might have reduced antithrombin, which would in turn lead to hypercoagulability (i.e. increased risk of clots forming where you don’t want them)?
Protein losing enteropathy (PLE) and Protein losing nephropathy (PLN)
Your patient comes in with a hemoabdomen. You perform clotting times and both PT and aPTT are markedly prolonged. Which of the following could explain this result:
- Deficiency in FVIII (Hemophilia A)
- Anti-coagulant rodenticide toxicity
- Patient was given too much heparin, which inhibited factor X and II
- Deficiency in FVII
- B and C
e. B and C
True or False: D-dimer elevation alone is diagnostic for DIC.
False
What do you measure to try to diagnose DIC?
Primary hemostasis - platelets
Secondary hemostasis – screening coagulation tests
Secondary hemostasis - fibrinogen
Fibrinolysis – D-dimer or FDP
Inhibitors - AT
Name a drug that is given to inhibit fibrinolysis, thereby stabilizing clots and (hopefully) preventing bleeding in cases like dogs with hemoabdomen from cancer or in trauma.
E- aminocaproic acid or tranexamic acid
Describe two reasons why there is loss of control of coagulation in DIC so that clotting happens at places other than where vessels are actually injured.
Decreased inhibitors
Expression of TF by cells that don’t normally express TF
Give three examples of diseases that can be associated with DIC.
Sepsis, severe inflammatory disease, and metastatic cancer
What is the best way you can treat DIC?
Treat the underlying disease
The most comment acquired disorders of secondary hemostasis are:
Rodenticide toxicosis and DIC
The most common hereditary disorder of secondary hemostasis is what?
Hemophilia A
What is the first test to do when you suspect primary hemostatic disorder?
platelet count
What tests do you do when you suspect a disorder of secondary hemostasis?
Prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin clot time (TCT)
