Hemostasis: Approach to Patient

Question 1

Primary hemostasis is _________.

Answer 1

platelet plug formation

Question 2

One megakaryocyte can divide into ________ platelets.

Answer 2

2,000

Question 3

Platelets can circulate for _______ in the bloodstream.

Answer 3

7-10 days

Question 4

Platelet maturation (from hematopoietic stem cells) is induced by _________.

Answer 4

thrombopoietin

Question 5

Following damage to the endothelium, _____ (on the platelets) bind _______ (in the sub-endothelium).

Answer 5

GPIb; von Willebrand factor

Question 6

What platelet receptor binds to both vWF and fibrinogen?

Answer 6

GPIIb/IIIa

Question 7

Safe platelet count for surgery is generally > ___________.

Answer 7

50,000

Question 8

What are the categories of thrombocytopenia?

Answer 8

(1) increased destruction; (2) decreased production; (3) increased sequestration; and (4) pseudo-thrombocytopenia, when platelets aggregate on the slide

Question 9

Infection–both viral and bacterial–can cause __________.

Answer 9

thrombocytopenia

Question 10

Marrow production can be affected by __________.

Answer 10

ETOH, malignancies, chemotherapy, radiation, viral infections, and nutritional deficiencies

Question 11

What is ITP?

Answer 11

Immunogenic Thrombocytopenia Purpura (formerly known as idiopathic thrombocytopenia purpura); it can happen acutely, following viral infection, or chronically, often accompanied by HIV, autoimmune, or malignancy

Question 12

How is ITP treated?

Answer 12

With steroids (to dampen the immune response), rituximab (to kill B cells and lower the amounts of IgG), or splenectomy (to remove the site of sequestration

Question 13

The most common congenital bleeding disorder is ________.

Answer 13

von Willebrand disease

Question 14

Patients with von Willebrand disease present with _________.

Answer 14

mucosal bleeding, nose bleeding, GI bleeds, menorrhagia, and bleeding after surgery

Question 15

Besides adhering platelets to collagen, vWF also ________.

Answer 15

carries factor VIII, and without vWF factor VIII has a short half life

Question 16

The most common type of VWD is _________.

Answer 16

partial quantitative defect of vWF (complete absence is rare)

Question 17

In patients with a normal spleen, what percent of platelets are circulating?

Answer 17

80%

Question 18

What procoagulant proteins do alpha granules contain in platelets?

Answer 18

Factor V, fibrinogen, and von Willebrand factor

Question 19

What role do platelets play in coagulation?

Answer 19

They (1) bind to sub-endothelial collagen and clog sites of injury; (2) activate receptors to interact and form the primary plug; (3) activate phosphatidylserine lipids to serve as sites of extrinsic tenase, intrinsic tenase, and prothrombinase activity; and (4) they release factor V, von Willebrand factor, and fibrinogen from their granules

Question 20

Describe the role of thromboxane A2 in platelet activation.

Answer 20

Platelet activation stimulates phospholipase A2 that cleaves off arachidonic acid; arachidonic acid then is converted to thromboxane A2 by COX1 and then activates other platelets.

Question 21

Glanzmann thrombasthenia is __________.

Answer 21

a rare autosomal recessive bleeding disorder in which patients lack GPIIb/IIIa; it causes easy bruising and petechiae

Question 22

Plavix (clopidogrel) and Ticlid (ticlopidine) are _________.

Answer 22

ADP receptor antagonists

Question 23

Immunogenic thrombocytopenic purpura is caused by ____________.

Answer 23

IgG against platelet antigens; acute cases (often following viral infection) usually auto-resolve; chronic cases don’t

Question 24

Thrombotic thrombocytopenic purpura results from __________.

Answer 24

damage to endothelial cell walls that leads to micro-clotting throughout the body and eventual consumption of platelets

Question 25

Multiple bleeding sites suggest _________, while mucocutaneous bleeding sites suggest ___________.

Answer 25

general hemostatic disorder; platelet dysfunction