Hematology - Levine Hemostasis SG

Question 1

What are the two key cellular players in primary hemostasis:

Answer 1

Endothelial cells and platelets

Question 2

What is the end result of primary hemostasis?

Answer 2

The formation of a platelet plug

Question 3

What are some clinical signs that you would you expect if a patient had a defect in primary hemostasis?

Answer 3

Petechiae, ecchymoses, epistaxis, hemoptysis, hematuria, hematemesis, melena, hematochezia, ocular bleeding, and CNS bleeding

Question 4

What are 4 main abnormalities that can lead to defective primary hemostasis?

Answer 4

Thrombocytopenia

Impaired platelet function

Von Willebrand factor deficiency

Impaired Von Willebrand function

Question 5

What is the most common acquired disorder of primary hemostasis?

Answer 5

Thrombocytopenia

Question 6

What is the most common hereditary disorder of primary hemostasis?

Answer 6

Von Willebrand factor deficiency

Question 7

List 4 possible causes of a prolonged BMBT.

Answer 7

Thrombocytopenic

Thrombopathic (platelets don’t work)

vWF deficient/abnormal

Abnormal vasculature

Question 8

What 3 tests would you want to perform to rule out secondary triggers of ITP?

Answer 8

Tick panel, imaging, and thorough drug history

Question 9

Explain how vincristine works to treat ITP:

Answer 9

It prevents microtubule polymerization

It promotes accelerated megakaryocyte fragmentation and platelet release from bone marrow

Question 10

True or False: Vincristine is an effective treatment for IMHA.

Answer 10

False

Question 11

Explain the basic idea behind IVIG therapy for ITP:

Answer 11

It blocks mononuclear phagocyte Fc receptor so that macrophages cannot engulf Ab coated platelets

Question 12

What are three blood products that contain platelets?

Answer 12

Fresh whole blood, platelet rich plasma, and fresh platelet concentrate

Question 13

What are three indications for a platelet transfusion?

Answer 13

Severe thrombocytopenia

Suspect pulmonary or CNS hemorrhage

Acquired or hereditary thrombopathias

Question 14

When would you give a platelet product transfusion to a dog with a platelet function problem (thrombopathia) that is not actively bleeding?

Answer 14

If they are going to surgery

Question 15

How does Clopidogrel (Plavix) work?

Answer 15

Inhibiting the platelet ADP receptor

Question 16

What cell surface is coagulation initiated on?

Answer 16

Fibroblast

Question 17

What cell surface is coagulation amplified and propagated on?

Answer 17

Platelets

Question 18

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.

Answer 18

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

Question 19

What is the target of tissue factor pathway inhibitor?

Answer 19

TF-FVIIa

Question 20

What is the target of antithrombin?

Answer 20

Thrombin, Factor Xa

Question 21

What is the target of protein C?

Answer 21

Factors V and VIII

Question 22

What are the two main factors/cofactors in the extrinsic pathway?

Answer 22

TV and VIIa

Question 23

If you have a delay in aPTT, but normal PT, what factors could be deficient?

Answer 23

Factos VIII, IX, XI, and XII

Question 24

What is the end result of the common coagulation pathway?

Answer 24

fibrin formation

Question 25

Spud, one of your favorite patients has Hemophilia A. If Spud were to bleed, which of the following signs would **not** be expected? 1. Petechiae 2. Joint bleed 3. Hemoabdomen 4. Hemothorax 5. Large ecchymoses

Answer 25

a. Petechiae Petechiae is associated with primary hemostasis. Hemophilia A is a disorder of coagulation factors which are associated with secondary hemostasis

Question 26

What inhibitor does heparin work with to inhibit secondary hemostasis and what clotting factors does it inhibit?

Answer 26

Inhibitor: Antithrombin Clotting factor: Factor II Clotting factor: Factor Xa

Question 27

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)?

Answer 27

Protein losing enteropathy (PLE) and Protein losing nephropathy (PLN)

Question 28

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: 1. Deficiency in FVIII (Hemophilia A) 2. Anti-coagulant rodenticide toxicity 3. Patient was given too much heparin, which inhibited factor X and II 4. Deficiency in FVII 5. B and C

Answer 28

e. B and C

Question 29

True or False: D-dimer elevation alone is diagnostic for DIC.

Answer 29

False

Question 30

What do you measure to try to diagnose DIC?

Answer 30

Primary hemostasis - platelets Secondary hemostasis – screening coagulation tests Secondary hemostasis - fibrinogen Fibrinolysis – D-dimer or FDP Inhibitors - AT

Question 31

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.

Answer 31

E- aminocaproic acid or tranexamic acid

Question 32

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.

Answer 32

Decreased inhibitors Expression of TF by cells that don't normally express TF

Question 33

Give three examples of diseases that can be associated with DIC.

Answer 33

Sepsis, severe inflammatory disease, and metastatic cancer

Question 34

What is the best way you can treat DIC?

Answer 34

Treat the underlying disease

Question 35

The most comment acquired disorders of secondary hemostasis are:

Answer 35

Rodenticide toxicosis and DIC

Question 36

The most common hereditary disorder of secondary hemostasis is what?

Answer 36

Hemophilia A

Question 37

What is the first test to do when you suspect primary hemostatic disorder?

Answer 37

platelet count

Question 38

What tests do you do when you suspect a disorder of secondary hemostasis?

Answer 38

Prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin clot time (TCT)