Ch4 - 2) Secondary Hemostasis and Related Disorders

Question 1

What does secondary hemostasis do?

Answer 1

Stabilizes the weak platelet plug via the coagulation cascade

Question 2

In secondary hemostasis the coagulation cascade generates?

Answer 2

thrombin, which converts fibrinogen in the platelet plug to fibrin.

Question 3

In secondary hemostasis what happens to fibrin?

Answer 3

It is cross-linked, yielding a stable platelet-fibrin thrombus.

Question 4

Where are the factors of the coagulation cascade produced?

Answer 4

In the liver in an inactive state.

Question 5

What does activation of the factors of the coagulation cascade require?

Answer 5

exposure to an activating substance, Phospholipid surface of platelets, calcium

Question 6

What are the activating substances involved in the activation of the factors of the coagulation cascade?

Answer 6

Tissue thromboplastin activates factor VII (extrinsic pathway). Subendothelial collagen activates factor XII (intrinsic pathway).

Question 7

Where does the Calcium involved in the activation of the factors of the coagulation cascade come from?

Answer 7

derived from platelet dense granules

Question 8

Disorders of secondary hemostasis are usually due to?

Answer 8

factor abnormalities

Question 9

What are the clinical features of disorders of secondary hemostasis?

Answer 9

they include deep tissue bleeding into muscles and joints (hemarthrosis) and rebleeding after surgical procedures (e.g circumcision and wisdom tooth extraction).

Question 10

Laboratory studies for Disorders of secondary hemostasis include?

Answer 10

PT (prothrombin time) and PTT (partial thromboplastin time)

Question 11

Prothrombin time (PT)

Answer 11

measures extrinsic (factor VII) and common (factors II, V, X, and fibrinogen) pathways of the coagulation cascade

Question 12

Extrinsic pathway of the coagulation cascade

Answer 12

factor VII

Question 13

Common pathway of the coagulation cascade

Answer 13

factors II, V, X, and fibrinogen

Question 14

Partial thromboplastin time (PTT) measures

Answer 14

intrinsic (factors XII, XI, IX, VIII) and common (factors II, V, X, and fibrinogen) pathways of the coagulation cascade

Question 15

What is involved in Hemophilia A?

Answer 15

Genetic factor VIII (FVIII) deficiency, X-linked recessive (predominantly affects males)

Question 16

Does Hemophilia A require a family history of it?

Answer 16

Can arise from a new mutation (de novo) without any family history

Question 17

Hemphilia A presents with?

Answer 17

deep tissue, joint, and postsurgical bleeding

Question 18

Clinical severity of hemophilia A depends on?

Answer 18

the degree of deficiency

Question 19

Laboratory findings of hemophilia A include

Answer 19

1. increased PTT; normal PT 2. decreased FVIII 3. Normal platelet count and bleeding time

Question 20

What does treatment of hemophilia A involve?

Answer 20

recombinant FVIII.

Question 21

What is christmas disease?

Answer 21

Hemophilia B - Genetic factor IX deficiency, Resembles hemophilia A, except FIX levels are decreased instead of FVIII

Question 22

What is coagulation factor inhibitor?

Answer 22

Acquired antibody against a coagulation factor resulting in impaired factor function; anti-FVIII is most common,

Question 23

Clinical and lab findings for hemophilia B?

Answer 23

its similar to hemophilia A, PTT does not correct upon mixing normal plasma with patient’s plasma (mixing study) due to inhibitor; PTT does correct in hemophilia A.

Question 24

How can you tell the difference between hemophilia A and B?

Answer 24

mixing study

Question 25

von Willebrand Disease

Answer 25

Genetic vWF deficiency

Question 26

What is the most common inherited coagulation disorder?

Answer 26

von Willebrand disease

Question 27

Does von Willebrand Disease result in qualitative or quantitative disorders?

Answer 27

Multiple subtypes exist, causing quantitative and qualitative defects;

Question 28

What is the most common type of von Willebrand Disease?

Answer 28

is autosomal dominant with decreased vWF levels

Question 29

von Willebrand Disease presents with?

Answer 29

mild mucosal and skin bleeding; low vWF impairs platelet adhesion.

Question 30

Laboratory findings for von Willebrand Disease include

Answer 30

1. increased bleeding time 2. increased PTT: normal PT ? Decreased FVIII half-life (vWF normally stabilizes FVIII); 3. Abnormal ristocetin test

Question 31

What is usually not seen with von Willebrand Disease that is unusual

Answer 31

deep tissue, joint, and postsurgical bleeding are usually not seen.

Question 32

Why is there an Abnormal ristocetin test in von Willebrand disease

Answer 32

Ristocetin induces platelet aggregation by causing vWF to bind platelet GPIb; lack ofvWF ?> impaired aggregation ?> abnormal test.

Question 33

What is the treatment for von willebrand disease?

Answer 33

desmopressin (ADH analog), which increases vWF release from Weibel-Palade bodies of endothelial cells

Question 34

How does vitamin K deficiency relate to hemostasis?

Answer 34

Disrupts function of multiple coagulation factors

Question 35

What is involved in Vitamin K activation?

Answer 35

Vitamin K is activated by epoxide reductase in the liver

Question 36

What does Activated vitamin K do?

Answer 36

it gamma carboxvlates factors II, VII, IX, X, and proteins C and S; gamma carboxylation is necessary for factor function.

Question 37

Vitamin K deficiency occurs in?

Answer 37

1. Newborns 2. Long-term antibiotic therapy 3. Malabsorption

Question 38

Why is there vitamin K deficiency in newborns?

Answer 38

its due to lack of GI colonization by bacteria that normally synthesize vitamin K; vitamin K injection is given prophylactic ally to all newborns at birth to prevent hemorrhagic disease of the newborn

Question 39

How does Long-term antibiotic therapy elad to Vitamin K deficiency?

Answer 39

disrupts vitamin K-producing bacteria in the GI tract

Question 40

How does Malabsorption lead to Vitamin K deficincy?

Answer 40

leads to deficiency of fat-soluble vitamins, including vitamin K

Question 41

What are some other causes of secondary hemostasis?

Answer 41

liver failure, large volume transfusion,

Question 42

How does liver failure lead to secondary hemostasis?

Answer 42

decreased production of coagulation factors and decreased activation of vitamin K by epoxide reductase;

Question 43

How is the effect of liver failure on coagulation followed?

Answer 43

followed using PT.

Question 44

How does Large-volume transfusion lead to secondary hemostasis?

Answer 44

it dilutes coagulation factors, resulting in a relative deficiency