Platelets

Front 1

What is the hormonal stimulus for platelet synthesis?

Back 1

thrombopoietin

Front 2

What are the 3 coordinated steps of forming a platelet plug?

Back 2

Adhesion via vWF and endothelial injury; aggregation via fibrinogen binding to GP IIb/IIIa on platelets, and TxA2, ADP, and others; Platelet secretion of ADP, vWF, and factor V

Front 3

Early in coagulation, what serves as a phospholipid scaffold?

Back 3

Platelets

Front 4

What does abnormal platelet activation lead to?

Back 4

arterial occlusion, heart attacks, and strokes

Front 5

If you suspect thrombocytopenia, what is the first thing to do?

Back 5

rule out pseudothrombocytopenia

Front 6

At what level do symptoms of thrombocytopenia show? When does it become dangerous?

Back 6

Symptoms between 50,000-20,000. Life-threatening 20,000-10,000.

Front 7

What are the symptoms of thrombocytopenia?

Back 7

mucocutaneous bleeding, aka "oozing and bruising."

Front 8

What are the 3 general etiologies of thrombocytopenia?

Back 8

underproduction, splenic sequestration, and peripheral destruction.

Front 9

What is the hallmark of underproduction of platelets?

Back 9

Inadequate numbers of megakaryocytes in the bone marrow.

Front 10

What are two important drugs that can cause underproduction of platelets?

Back 10

chemotherapy and alcohol.

Front 11

What are the 2 classes of thrombocytopenia due to destruction?

Back 11

Non-immune mechanisms and immune mechanisms

Front 12

What are the 2 important types of non-immune peripheral destruction of platelets?

Back 12

DIC, and TTP

Front 13

Definition of DIC

Back 13

abnormal activation of coagulation, generation of thrombin, consumption of clotting factors, and peripheral destruction of platelets.

Front 14

What are the 4 most important diagnostic signs of DIC?

Back 14

Elevated PT (prothrombin time), elevated D-dimers or FDPs, low platelets, and maybe schistocytes if there is MAHA.

Front 15

Definition of TTP

Back 15

abnormal activation of platelets and endothelial cells, deposition of fibrin in the microvasculature, and peripheral destruction of red cells and platelets.

Front 16

What is the pentad of TTP symptoms and which are required?

Back 16

1. microangiopathic hemolytic anemia- characterized by high LDH and schistocytes. Required!

2. Thrombocytopenia, required!

3. fever: not always seen
4. renal manifestations: not always seen
5. neurologic manifestations: not always seen.

Front 17

What clinical lab findings distinguish TTP from DIC?

Back 17

For thrombotic thrombocytopenia fibrinogen, PT, FDPs, D-dimers are all generally normal.

Front 18

What is generally thought to be the etiology of TTP?

Back 18

Antibodies attack ADAMTS-13, an enzyme that cleaves the multimers of vWF. Ultra-high weight multimers of vWF accumulate and lead to abnormal platelet adhesion and activation.

Front 19

Under what 4 condition is the risk of TTP increased?

Back 19

pregnancy, HIV/AIDS, bone marrow transplants, solid organ transplants.

Front 20

What is the most important treatment for TTP?

Back 20

plasma exchange removes some of the high-weight vWF and the auto-antibodies, and replace them with fresh ADAMTS-13

Front 21

what should you ABSOLUTELY not do for a patient with TTP?

Back 21

NO platelet transfusions. It will just "fuel the fire!"

Front 22

What can TTP overlap with?

Back 22

HUS, which is usually caused by intestinal infections like O157:H7

Front 23

What causes immune-mediated thrombocytopenia?

Back 23

antibodies binding to platelets, which are destroyed by macrophages.

Front 24

what is the diagnostic test for immune thrombocytopenia?

Back 24

none

Front 25

which drugs can cause immune thrombocytopenia?

Back 25

beta-lactams, sulfa drugs (especially bactrim), heparin, and quinine/quinidine

Front 26

Is ITP associated with splenomegaly?

Back 26

no

Front 27

What is ITP usually associated with in children?

Back 27

viral infections

Front 28

what is initial therapy for ITP?

Back 28

corticosteroids, then splenectomy if they don't work

Front 29

What are two adjunctive therapies for ITP?

Back 29

IVIG (IV Immunoglobulin), or Rho gam.

Front 30

What is the pathogenesis of thrombocytopenia due to splenic sequestration?

Back 30

splenomegaly

Front 31

What is the most common cause of splenomegaly?

Back 31

portal hypertension

Front 32

What are the two situations to use platelet transfusion in cases of thrombocytopenia or thrombocytopathy?

Back 32

treatment of bleeding, prophylaxis against bleeding.

Front 33

When may platelets be transfused for ITP?

Back 33

in cases of severe bleeding.

Front 34

When to transfuse for TTP?

Back 34

NEVER

Front 35

Will platelet transfusions work for thrombocytopenias due to splenic sequestration?

Back 35

no

Front 36

What are the two primary thrombocytoses to know?

Back 36

Essential thrombocythemia and polycythemia vera.

Front 37

What are the secondary thrombocytosis causes?

Back 37

inflammation, bleeding, iron deficiency

Front 38

How do you diagnose qualitative disorders of platelets?

Back 38

abnormal bleeding times.

Front 39

How does clopidogrel work?

Back 39

It blocks the action of ADP (a platelet agonist).

Front 40

What is Abcximab?

Back 40

Blocks GP IIb/IIIa