Normal Hemostasis

Question 1

T or F. Thrombin cleaves two fibrinopeptides (A and B) from fibrinogen to make fibrin

Answer 1

T, going from an an soluble fibrinogen to a insoluble fibrin

Question 2

What activates Factor XIII?

Answer 2

thrombin

Question 3

What does FXIII do?

Answer 3

converts the hydrogen bond between fibrin and platelets to a covalent bond

Question 4

What is needed for conversion of prothrombin to thrombin?

Answer 4

-calcium
-Xa/Va
and a phospholipid surface

Question 5

How is FVIII activated once released from alpha granules on platelets?

Answer 5

TF (it then binds to IXa)

Question 6

What is lacking in serum?

Answer 6

fibrinogen

Question 7

How is a PT done?

Answer 7

add TF + phospholipid (aka thromboplastin) complex (used to promote clotting for a PT time along with Ca2+ input) to PLASMA not serum (extrinsic)

Question 8

How is aPTT done?

Answer 8

use citrated plasma and add phospholipid only (without TF) and add Ca2+ and a negative charge and measure time (intrinsic)

Question 9

What clotting factor deficiency could you have if you had a normal PT and a long PTT?

Answer 9

VIII, IX, XI, or XII

Question 10

What clotting factor deficiency could you have if you had a long PT and a normal PTT?

Answer 10

VII

Question 11

What clotting factor deficiency could you have if you had a long PT and a long PTT?

Answer 11

X, II

Question 12

What clotting factor deficiency could you have if you had a normal PT and a normal PTT?

Answer 12

XIII (very rare)

Question 13

How could you screen for XIII deficiency cheaply?

Answer 13

you would have a hydrogen bonded clot that didn’t get covalently bonded so you can put the clot in something unfavorable to hydrogen (5M-urea) and see if it dissociates

Question 14

What does VIII need to function (bind)?

Answer 14

vMF (it the carrier of factor VIII)

Question 15

T or F. vMF is normal in Hemophilia A patients

Answer 15

T. patients just cant make VIII

Question 16

What is D-dimer?

Answer 16

a combo that is never seen on fibrin and indicates fibrinolysis of cross-linked fibrin (good diagnostic tool for suggesting a clot has formed-PE or MI- not perfect)

(fibrinogen digestion products can be indicative of fibrinogen breakdown- not fibrin)

Question 17

What is the MOI of Hemophilia?

Answer 17

X-linked recessive (thus women are the only carriers)

Question 18

What does thrombomodulin do?

Answer 18

located on endothelial cells and changes thrombin’s target to activate protein C (vitamin K dependent)

Question 19

What is Factor V Leiden?

Answer 19

mutation in V that makes it resistant to inactivation via protein C

Question 20

What does antithrombin III do?

Answer 20

made in liver binds to heparin and is a protein that neutralizes the serine protease active site (on II, X, and IX- not VII)

Question 21

What does heparin do?

Answer 21

essentially catalyzes antithrombins ability to neutralize the serene proteases II, IX, and X

Question 22

T or F. Heparin sulfate in the body are naturally occurring antithrombin catalysts.

Answer 22

T.

Question 23

T or F. Plasmin is not found floating in the body.

Answer 23

T. because antiplasmin a2 will neutralize it quickly

Question 24

The differential diagnosis for thrombocytopenia should always start with what?

Answer 24

lab artifact- pediatric or adult

Question 25

What is the target population for TTP?

Answer 25

women in 20-30s

Question 26

T or F. TTP is an autoimmune disease

Answer 26

T. antibody to ADAMTS13 which trims vMF

Question 27

What is the cause of death in TTP?

Answer 27

ischemic organ failure

Question 28

What is the treatment for TTP?

Answer 28

plasma exchange therapy

Question 29

What is the diagnosis for ITP?

Answer 29

diagnosis of exclusion (garbage can category)

rule out problems with sequestration, bone marrow function and then call it this

Question 30

What is ITP?

Answer 30

immune (idiopathic) thrombocytopenia purpura

Question 31

In a pediatric setting, ITP can be a good cause if a child comes in with a lot of bruises (think abuse too) and will resolve mostly.

Answer 31

In a pediatric setting, ITP can be a good cause if a child comes in with a lot of bruises (think abuse too) and will resolve mostly.

Question 32

T or F. In ITP antibodies that bind platelets, they are likely to bind megakaryocytic too

Answer 32

Thus, decreased production is also a problem with ITP

treat with steroids here