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Flashcards in Coagulation 2 Deck (57):
1

Platelets are produced from?

Cytoplasmic projections of megakaryocytes

2

Production of platelets is regulated by? What receptor does this interact with?

Thrombopoietin which interacts with the c-MPL receptor

3

Where is thrombopoietin produced?

The liver and bone marrow stromal cells

4

How long do platelets circulate for?

7-10 days

5

What 3 things are secreted by platelets once activated?

1. Dense granules
2. Alpha granules
3. Acid hydrolase

6

What is the role of TXA2?

Prevents further activation by the agonist

7

What inherited disorders can cause platelet issues?

Albinism, deafness, and nephritis

8

What systemic diseases can lead to platelet issues?

Renal, hepatic, and myeloproliferative disease

9

What are the two types of quantitative disorders?

Thrombocytopenia where the count is reduced
Thrombocytosis where the count is raised

10

What 3 things can cause thrombocytopenia?

Decreased production, increased destruction, and splenomegaly

11

What can cause thrombocytosis?

Reactive to infection and autonomous

12

What is the normal range for platelet count?

150000-400000

13

What is pseudothrombocytopenia?

When there is clumping of platelets in the presence of EDTA leading to a lower count. Caused by EDTA-dependent antibodies

14

What 3 things can cause thrombocytopenia?

1. Marrow replacement
2. Marrow failure as seen in aplastic anemia where fibrosis takes over
3. Marrow injury from radiation or drugs

15

What are the 2 types of inherited thrombocytopenias with small platelets?

Wiskott-Aldrich and X-linked thrombocytopneia

16

What is the main thrombocytopenia with normal sized platelets?

Familial platelet disorder with predisposition to AML

17

What are 2 types of thrombocytopenia with large platelets?

Bernard-Soulier and grey platelet syndrome

18

What is the most common thrombocytopenia due to increased destruction>

Immune thrombocytopenic purpura

19

What 4 drugs can cause increased platelet destruction?

Heparin, quinidine, vancomycin, and GPIIb antagonists

20

Post transfusion purpura occurs in those lacking what antigen?

HPA-1a antigen

21

Most cases of immune thrombocytopenic purpura are?

Acute

22

Acute ITP is usually preceded by?

Viral infection

23

Does chronic ITP have something preceding it?

No insidious onset

24

In isolated thrombocytopenia platelets count will be? What other findings?

Less than 100,000 and they will be large.

Increased megakaryocytes in bone marrow and increased platelet associated IgG

25

Heparin caused what type of thrombocytopenia? This is most common with what type of heparin?

Immune mediated

Heparin of high molecular weight

26

The reduced count results in?

Venous and arterial thrombosis, limb loss, death

27

How do you treat heparin induced thrombocyto?

Discontinue heparin and use a thrombin inhibitor like argatroban or recombinant huridin (refludan)

28

What are the 3 non-imune associated thrombocytopenias?

1. DIC
2. Hemolytic uremic syndrome
3. Thrombotic thrombocytopenic purpura

29

What causes TTP?

Reduced ADAMTS-13 metalloprotease activity

30

How does heparin cause problems?

Binds to PF4 on the platelet leading to an Ig form in against the complex

31

Hemolytic uremic syndrome occurs in?

Infants and young children

32

What does hemolytic uremic syndrome cause? What causes it?

Bloody diarrhea

Infection by E. Coli O157:H7

33

How does hemolytic uremic syndrome differ from TTP?

Less pronounced neurologic symptoms and more pronounced renal symptoms. There is normal ADAMTS13

34

How is hemolytic uremic syndrome treated?

Dialysis

35

What are the two types of congenital qualitative disorders?

Disorders of membrane glycoprotein and disorders of intracellular proteins

36

How is Bernard Soulier syndrome inherited and what does it cause?

Autosomal recessive, leads to abnormal platelet adhesion

37

There is a defect in what gene in Bernard Soulier?

GP1b gene

38

How is Bernard Soulier treated?

DDAVP or PLT transfusion

39

Other than Bernard Soulier what other disorder can cause aggregation problems?

Glanzmann thrombasthenia

40

How is TTP treated?

Plasmapheresis and steroids

41

How is hemolytic uremia treated?

Dialysis

42

Describe the appearance of platelets in Bernard Soulier.

Giant platelets with a pseudonucleus

43

What are the 4 diseases of dense granule storage pool deficiency?

1. Hermansky Pudiak
2. Chediak-Higashi
3. Thrombocytopenia with absent radii
4. Wiskott-Aldrich

44

Hermansky Pudiak presents with?

Severe oculocutaneous albinism

45

Chediak Higashi presents with?

Partial albinism, large cytoplasmic granules, defective WBC function

46

Defects in thromboxane synthesis occur due to?

Defects in the AA pathway

47

What is an extrinsic acquired qualitative disorder?

Normal platelet but bad environment

48

What are the 2 causes of extrinsic qualitative

Uremia and paraproteinemia where IgG coats the platelets

49

What two things can cause intrinsic qualitative disorders?

Drugs and myeloproliferative neoplasms

50

What is the most frequent inherited bleeding disorder?

von Willebrand disease

51

How is vWF stored?

Weibel-palade bodies in endothelial cells and alpha granules of platelets

52

What are the two general functions of vWF?

Adhesion and a carrier protein for factor 8

53

What can exacerbate bleeding in those with vWF disease?

Aspirin

54

What types of vWF disease lead to severe bleeding episodes?

2 and 3

55

How much deficiency is there in vWF type 1? Leads to mild/moderate/severe disease?

Partial deficiency with normal vWF, mild to moderate disease

56

Type 1 or 3 makes up the majority?

Type 1

57

Describe vWF disease type 3.

Severe disorder, total or near deficiency of vWF, secondary deficiency of factor 8 and defect in clotting