Primary Hemostasis

Question 1

Primary hemostasis forms a (blank) which is stabilized by secondary hemostasis

Answer 1

weak platelet plug

Question 2

What are the four steps of primary hemostasis?

Answer 2

1. transient vasoconstriction
2. platelet adhesion to the surface of the disrupted vessel
3. Platelet degranulation
4. Platelet aggregation

Question 3

What two things mediated the immediate vasoconstriction of a damaged blood vessel?

Answer 3

neural stimulation and endothelin

Question 4

What binds to exposed subendothelial collagen?

Answer 4

vWF

Question 5

Platelets bind to vWF using the (blank) receptor

Answer 5

GpIb

Question 6

vWF is derived from the (blank) bodies of endothelial cells and the (blanks) of platelets

Answer 6

Weibel-Palade bodies of endo

a-granules of platelets

Question 7

PLT adhesion induces a shape change which causes degranulation releasing what three things?

Answer 7

1. ADP
2. TXA2
3. GPIIb/IIIa

Question 8

What is the function of GPIIb/IIIa?

Answer 8

promotes PLT aggregation

Question 9

What is the function of ADP?

Answer 9

promotes expression of GpIIb/IIIa

Question 10

What is the function of TXA2?

Answer 10

promotes PLT aggregation

Question 11

PLTs aggregate via GPIIa/IIIa using (blank) as a linking molecule, forming a PLT plug

Answer 11

fibrinogen from the plasma

Question 12

T/F: the coag cascade is not necessary to stabilize the PLT plug

Answer 12

false

Question 13

disorders of primary hemostasis are due to disorders of what cell type?

Answer 13

PLT

Question 14

what is the most common feature in a primary hemostatic disorder?

Answer 14

epistaxis

Question 15

What is a normal bleeding time?

Answer 15

2-7 minutes

Question 16

Is skin bleeding like petechia associated with thrombocytopenia or a qualitative PLT disorder?

Answer 16

thrombocytopenia

Question 17

What is the most common cause of thrombocytopenia in adults and kids?

Answer 17

immune thrombocytopenic purpura (ITP)

Question 18

What Ab class mediates ITP?

Answer 18

IgG

Question 19

What cells produce the Ig in ITP?

Answer 19

plasma cells of the spleen

Question 20

What does the IgG target in ITP?

Answer 20

GPIIB/IIIa on PLTs

Question 21

What cells consume the Ab-bound PLTs in ITP?

Answer 21

macrophages of the spleen

Question 22

why is splenectomy effective in ITP?

Answer 22

removes source of Ab and source of destruction of PLTs

Question 23

T/F: acute ITP is life threatening emergency

Answer 23

false; self limited to children after viral infx; resolves within weeks

Question 24

What demographic normally gets chronic ITP?

Answer 24

women of childbearing age

Question 25

What disease state is associated with ITP?

Answer 25

SLE

Question 26

T/F: newborns will have shortlived thrombocytopenia if the mother has ITP

Answer 26

true; IgG can cross the placenta; will resolve once the newborn destroys all the maternal IgG

Question 27

Describe the following labs for ITP: PLT PT/PTT bone marrow biopsy

Answer 27

low PLT nomral PT/PTT: coag cascade not involved!! increased megakaryocytes on bone marrow biopsy

Question 28

What is the initial Tx for ITP? Is it effective?

Answer 28

corticosteroids; adults often relapse

Question 29

How is IVIG used in ITP?

Answer 29

used to temp. increases PLTs; just buys you time

Question 30

Why do you get low PLTs in MAHA?

Answer 30

PLTs consumed in the formation of small clots

Question 31

What type of RBC abn. will you see on a smear of someone with MAHA? Why?

Answer 31

Schistocytes; RBCs are sheared when going past microthrombi

Question 32

MAHA is seen in what two qualitative PLT disorders?

Answer 32

TTP and HUS

Question 33

What is the cause of TTP? Explain the mechanism?

Answer 33

Decreased ADAMTS13 enzyme which cleaves vWF multimers into single units

Question 34

Is decreased ADAMTS13 levels a congenital or acquired def?

Answer 34

acquired strangely enough!; seen in adult females

Question 35

(TTP/HUS) is caused by drugs or infection

Answer 35

HUS

Question 36

(TTP/HUS) is caused by E. coli O157:H7 dysentery from undercooked beef

Answer 36

HUS

Question 37

What E. coli toxin damages endothelial cells in the kidney and brain in HUS?

Answer 37

E. coli verotoxin

Question 38

What are the common clinical findings in TTP/HUS?

Answer 38

1. skin and mucosal bleeding 2. MAHA 3. fever

Question 39

What clinical finding lets you know you have HUS and TTP?

Answer 39

renal insufficiency

Question 40

What clinical finding lets you know you have TTP and not HUS?

Answer 40

CNS abnormalities

Question 41

``` What are the lab values for TTP and HUS: PLT bleeding time PT/PTT Hgb Peripheral smear Bone marrow biopsy ```

Answer 41

low PLT increased bleeding time nomral PT/PTT; coag cascade not involved!!! low Hgb aka anemia schistocytes on smear increased megakaryocytes on bone marrow biopsy

Question 42

Bernard-Soulier syndrome is due to a genetic (blank) deficiency causing impaIred platelet ADHESION

Answer 42

GPIb

Question 43

What finding do you see on smear in Bernard-Soulier syndrome?

Answer 43

enlarged PLTs; Big-Suckers

Question 44

Glanzmann thrombasthenia is a genetic (blank) deficiency causing impaired PLT AGGREGATION

Answer 44

GPIIb/IIIa

Question 45

Aspiriin irreversibly inhibits COX leading to a lack of (blank) and impairs aggregation

Answer 45

TXA2

Question 46

T/F: both adhesion and aggregation are impaired in uremia

Answer 46

true