Ho: Platelets

Front 1

What is seen here?

Back 1

Petechiae

Front 2

What is seen here?

Back 2

Purpura

Front 3

Thrombocytopenia is...
Thrombocytosis is...

Back 3

...too few platelets.
...too many platelets.

Front 4

What is the first thing to rule out when you see a low platelet count? How do we do this?

Back 4

pseudothrombocytopenia, AKA “platelet clumping”

... makes the count artifactually low.

make a peripheral blood smear.

Front 5

When do we see the first symptoms of low platelet count? When to we need to treat? When do we need to transfuse?

Back 5

<50,000

20k to 10k... maybe not transfuse tho'.

sub 10k, transfuse now.

Front 6

Three broad categories of causes of thrombocytopenia?

**THIS IS EXTREMELY IMPORTANT TO KNOW**

Back 6

Underproduction
Peripheral Destruction
Splenic sequestration

Front 7

What are some causes of platelet underproduction?

Back 7

Marrow failure: myelodysplasia, aplastic anemia, vitamin deficiencies

Marrow infiltration: tumor, granulomatous diseases, fibrosis, leukemias, lymphomas

Marrow toxins: drugs, radiation, infections

Front 8

Two types of peripheral destruction of platelets (and examples of 'em)?

Back 8

Non-immune - DIC, TTP

Immune mechanism - provoked by drugs, associated w/ HIV, can be associated with other autoimmune disease, can be ideopathic.

Front 9

What is DIC? What is another word for it?

Back 9

A process, characterized by abnormal activation of coagulation, generation of thrombin, consumption of clotting factors, destruction of platelets, and activation of fibrinolysis.

Consumptive coagulopathy

Front 10

How can we treat DIC? What can cause it?

What supportive measures can we take?

Back 10

TREAT THE UNDERLYING CAUSE
Can be associated with gram negative sepsis, severe burns, obstetrical disasters, certain leukemias or tumors, shock, insect or snake venoms

platelet transfusion, clotting factors (FFP), fibrinogen (cryoprecipitate)

Front 11

How do we diagnose DIC?

Back 11

Elevated PT - due to consumption of Factor VII, which has the shortest half-life (4 hrs) of all clotting factors.
When advanced, the PTT can be prolonged as well, as the other clotting factor levels fall.
Low platelets
Low/falling fibrinogen
Elevated fibrin degradation products (FDPs/FSPs) or D-Dimers
Can see a few schistocytes on the peripheral smear in most cases.

Front 12

What clotting factor has the shortest half0life of all clotting factors?

Back 12

factor VII.

Front 13

What is TTP?

Back 13

A process, characterized by abnormal activation of platelets and endothelial cells, with VWF and fibrin deposition in the microvasculature, and peripheral destruction of platelets and red cells

Front 14

What is "the pentad" of Dx features for TTP?

Which 2 MUST be present for Dx?

Back 14

Microangiopathic Hemolytic Anemia (MAHA)
Elevated LDH, elevated bilirubin
Schistocytes on the peripheral smear
MUST BE PRESENT
Low platelets - MUST BE PRESENT
Fever
Neurologic Manifestations
- headache, sleepiness, confusion, stupor, stroke, coma, seizures
Renal Manifestations
hematuria, proteinuria,
^ BUN/Creatinine

Schistocytes (MAHA), Low platelets

Front 15

What is seen here? What disease likely underlies this smear?

Back 15

Low platelets, schistocytes.

TTP

Front 16

What disease requires a hematologist to diag. and treat? What happens if it's not Dx-ed?

Back 16

TTP. Death (possible, I guess)

Front 17

Differentiate bt DIC and TTP?

Back 17

DIC - actv liquid coag, and the platelets are being consumed.

TTP - process begins with the platets.

Front 18

What is the etiology of TTP? What is the name of the involved protease?

Back 18

normally vWF is secreted from the endothelial cells, and a protease cuts it down to normal size. W/o this snipping, it's WAY TOO LONG. Platelets get stuck on this ultra-long multimer, and get stuck in the vasculatrue.

TTP people have an antibody directed against the protease.

ADAMTS-13

Front 19

Is TTP an autoimmune disorder?

Back 19

Yes. It's just that the antibodies aren't against the platelets.

Front 20

How do we differentiate b/t DIC and TTP clinically if both can show schistocytes?

Back 20

DIC will have eleveated PT and low fibrogenogen.

Front 21

What drug can induce TTP? Which two drugs can induce something like TTP but don't involve ADAMTS-13

Back 21

quinine

cyclosporine, tacrolimus - drugs that block T-cell function used in organ transplant... can incite antibodies to other things, not ADAMTS-13

Front 22

Increased incidence of TTP with...

Back 22

pregnancy or HIV

Front 23

What is the treatment for TTP?

What kind of transfusions should be avoided? Why? What if their platelet count is sub-10k? What about in the middle of a head bleed?

Are glucocorticoids and anti-platelet agents any help in TTP Tx?

Back 23

PLEX - Exchange plasma transfusions.
Remove all inciting agents

Platelet transfusions, they fuel the fire. Still don't do it. Do it, but damn.

uncertain benefit, but are used sometimes.

Front 24

What precipitates HUS? What is it produced by? What does it do?

Back 24

Shiga toxin, produced by E.coli 0157:H7.

It b/endothelial cells in the kidney --> cell death.

Front 25

Which drugs can lead to drug-induced immune-mediated thrombocytopenia?

Back 25

Beta-lactam antibiotics
Trimethoprim-sulfamethoxazole and other sulfa drugs
Quinine/quinidine
Heparin
Abciximab (ReoPro®)

Front 26

How can drugs lead to immune-mediated thrombocytopenia? (3)

Back 26

1) directly stimulating anti-platelet antibody production
2) a hapten mechanism
3) “innocent bystander” phenomenon.

Front 27

Do platelet counts have to be abnormal in Heparin-induced Thrombocytopenia? What does have to happen?

Back 27

No. It just has to fall.

Front 28

If a patient on heparin has their platelets fall a bit, what do we do?

Back 28

STOP THE HEPARIN

Front 29

What can Heparin-Induced Thrombocytopenia (HIT) cause (paradoxically)?

why can this be super bad?

Back 29

Thrombosis.

the initially feeling is to just increase the heparin. bad shit.

Front 30

What is ITP?

How do we make the Dx (methodologically speaking)?

Back 30

Immune/Idiopathic Thrombocytopenic Purpura

By exclusion. There is NO Dx test, unlike AIHA.

Front 31

What will be present in the marrow in ITP

Back 31

megakaryocytes.

Front 32

What is ITP usually provoked by in children? Tx?

When do we Tx adults? How do we Tx them acutely?

Back 32

viral illness. Nothing usually required.

In adults, specific therapy required if platelet count is <30-50 or if patient is bleeding.

Initial: corticosteroids.
If platelet count is <10k or patient is bleeding, use IVIg. If patient is Rh +, can use Anti-D (WinRho) in place of IVIg.

Front 33

Will most patients with ITP relapse after steroids/acute treatment? What is the 2nd line treatment?

Will this help all patients?

Back 33

Yes (2/3) Splenectomy.

No. 1/3 will relapse, and require more intense immunosuppression.

Front 34

Before taking out a spleen, if you have time, what should you do?

Back 34

immunize against encapsulated organisms.

Front 35

Is HUS seen more often in kids or adults? Where does it have a better prognosis?

Back 35

kids. kids.

Front 36

How does Anti-D (WinRho) work?

Back 36

Rhogams induces hemolytic anemia by using the RBCs as a decoy, binds them and targets them for destruction. This gives the platelets time to get back up their #.

Front 37

Normally, __ of total platelet mass resides in spleen.
Splenic enlargement, from any cause, can lead to _________ from peripheral circulation into splenic pool.

Back 37

1/3

displacement of placements

Front 38

Can we induce sequestered platelets in the spleen to come out? Given this, should the spleen be seen as a resevoir of platelets?

Back 38

No.

No.

Front 39

Biggest cause of Splenomegaly in US? Other important ones?

Back 39

Portal hypertension from cirrhosis

Some malignancies
Chronic Hemolytic diseases

Front 40

Do we transfuse platelets to people w/ ITP if they're not bleeding? why?

Back 40

no. cause they'll destroy 'em.

Front 41

In splenic sequestration, should we transfuse platelets?

Back 41

not really, because they'll home to the spleen too.

Front 42

How do we Dx Qualitative disorders of platelets? What do we do here at UNC?

Will PT/PTT/TCT be changed?

Back 42

Bleeding time

Platelet Function screen - gives an in-vitro bleeding time.

No, should be normal.

Front 43

What is Glanzmann's thrombaesthenia?

Back 43

Congenital Qualitative Platelet disorder

defect in IIb/IIIa on platelet surface

Front 44

Bernard-Soulier disease?

Back 44

Congenital Qualitative Platelet disorder

defect in Ib/IX on platelet surface

Front 45

What are 3 acquired qualitative platelet disorder?

Back 45

uremia

ASA/NSAIDS

Myeloproliferative diseases

Front 46

Asprin inhibits...

Back 46

...COX-1

Front 47

Does ASA reduce recurrent arterial event risk? Primary?

Back 47

Yes. Yes.

Front 48

What is Clopidogrel (Plavix)? When are they used?

Back 48

Inhibit platelet function by blocking ADP action. ADP is a platelet agonist.

Used in cases where ASA has failed.

Front 49

What do GP IIb/IIIa inhibitors do?

Back 49

act to block fibrogen receptor on platelets (IIb/IIIa), thus INHIBIT PLATELET AGGREGATION

Front 50

Essential Thrombocythemia, Polycythemia Vera, CML, and myelofibrosis all are what type of disease?

Are these platelets hyper- or hypo- functional?

Do these diseases lead to clotting or bleeding?

Back 50

Primary Thrombocytosis.

BOTH.

Can lead to either or BOTH at the same time.

Front 51

Which type of thrombocytosis usually does not lead to thrombosis?

What are some causes of this type of thrombocytosis?

Back 51

Secondary (reactive) thrombocytosis.

inflammation, infection, bleeding, iron def.

Front 52

What is another word for myeloproliferative syndromes? examples?

Back 52

primary throbocytosis syndromes

Essential Thrombocythemia, polycythemia vera, CML, myelofibrosis

Front 53

Platelets are made in the bone marrow from progenitor cells called...

Normal life span of a platelet?
Normal Platelet count?

Back 53

...megakaryocytes.

10 days.

150-450,000/mL

Front 54

What is the cell in the middle? what is it the progenitor of?

Back 54

Megakaryocyte

Platelet.

Front 55

Describe the 3 ways that platelets form plugs.

Back 55

Adhesion - Platelets stick to injured vessel wall.

Aggregation - Platelets stick to each other via fibrinogen bridges.

Secretion - Platelets release granular contents and potentiate clotting

Front 56

what does vWF do?

Back 56

It b/ to platelets and helps them adhere by also b/ collagen exposed during injury

carrier for VIII