PLATELET DISORDERS Flashcards Preview

HAEMATOLOGY > PLATELET DISORDERS > Flashcards

Flashcards in PLATELET DISORDERS Deck (35):
1

What cells are platelets produced from?

Megakaryocytes in the bone marrow

2

Upon release from the bone marrow, where do young platelets travel to?

Spleen, where they are trapped for 36 hours before entering circulation

3

What is the normal lifespan of a platelet?

7-10 days

4

What is the normal platelet count for all age groups?

150-450 x10^9/L

5

What is the MPV (mean platelet volume)?

8-11 fL

6

What is a reticulated platelet?

A young platelet still containing RNA

7

Why is it useful to know about the proportion of platelets that are reticulated? What is the normal proportion?

Indirectly indicate state of marrow production
8-16%

8

What is the factor responsible for aiding platelet-endothelial cell adhesion?

von Willebrand factor

9

What is the factor responsible for aiding platelet-platelet adhesion?

Fibrinogen (factor I)

10

What is the glycoprotein found on the platelet membrane for which von Willebrand factor is the main binding protein?

Ib/IX complex

11

What is the glycoprotein found on the platelet membrane for which fibrinogen is the binding protein?

IIB/IIIa complex

12

What is contained within the intracellular dense granules of platelets?

Nucleotides
Calcium
Serotonin

13

What is contained within the intracellular alpha-granules of platelets?

Fibrinogen
von Willibrand factor
Platelet-derived growth factor
Clotting factors

14

How do platelets aid clotting in normal haemostasis?

Platelet aggregation forming platelet plugs
Release contents of granules
Provide an extensive phospholipid surface for interaction and activation of clotting factors in coagulation pathway

15

What is Fanconi's anaemia?

Autosomal recessive preleukaemic condition which presents as thrombocytopenia. The cardinal laboratory feature is abnormal chromosomal fragility. Requires bone marrow transplant.

16

What is thrombocytopenia with absent radii?

TAR syndrome presents with the pathognomic sign of bilateral absent radii bones and with severe neonatal thrombocytopenia. Thrombocytopenia often improves after first year.

17

What is Wiskott-Aldrich syndrome?

X linked disorder with a triad of thrombocytopenia, eczema and T-cell immunodeficiency. Requires bone marrow transplant.

18

What is the most common cause of mild transient thrombocytopenia?

Viral infection

19

What is the most common cause isolated thrombocytopenia (without anaemia or neutropenia)?

Idiopathic thrombocytopenia purpura - autoimmune disease

20

What diseases is idiopathic thrombocytopenia purpura associated with?

SLE
Primary antiphospholipid syndrome

21

Who is most likely to suffer from post-transfusion purpura?

Multiparous women who are negative for human platelet antigen.

22

What is neonatal alloimmune thrombocytopenia?

Similar to haemolytic disease of the newborn but antigenic stimulus is from platelets not red cells.

23

What drugs can be responsible for thrombocytopenia?

Heparin
Penicillamine
Cotrimoxadole

24

What is the feature of heparin-induced thrombocytopenia?

Thrombosis causing thrombocytopenia

25

What are the features of thrombotic thrombocytopenia purpura?

Clinical symptoms affecting any organ but primarily manifesting as neurological symptoms resulting from microvascular thrombosis.

26

What is the underlying cause of thrombotic thrombocytopenia purpura?

Deficiency of ADAMTS 13

27

How might someone with suspected thrombocytopenia present?

Abnormal bleeding
Spontaneous skin purpura
Ecchymoses (bruise)
Mucous membrane bleeding
Prolonged nosebleeds
Menorrhagia

28

What investigations should be ordered for someone with suspected thrombocytopenia?

FBC
Coagulation
Biochemical screen
Blood film

29

How are congenital thrombocytopenias managed?

Filtered human leucocyte antigen compatible platelet transfusions
Desmopressin IV may work in minor episodes
Tranexamic acid
Recombinant factor VII may also prove useful
Bone marrow transplantation offers a cure

30

How are acquired thrombocytopenias managed?

Filtered human leucocyte antigen compatible platelet transfusions

31

How is life threatening childhood idiopathic thrombocytopenic purpura managed?

Corticosteroids
IV immunoglobulins

32

How is adult idiopathic thromobocytopenic purpura managed?

Prednisolone and/or IV immunoglobulins
Rituximab in refractory patients

33

How is someone with post-transfusion purpura managed?

IV immunoglobulin
Plasma exchange

34

How is someone with thrombotic thrombocytopenic purpura managed?

Large volume plasma exchange
Aspirin
Avoid platelet transfusion

35

How do you manage someone with DIC (disseminated intravascular coagulation)?

Fresh frozen plasma
Platelet transfusion