Platelet Disorders Flashcards

1
Q

Thrombocytopenia

Etiology

A
  1. Decreased production (bone marrow disease; nutrition deficiency)
  2. Increased destruction (Medication, alcohol, autoimmune disease, DIC)
  3. Sequestration by spleen
    * First needs to r/o pseudothrombocytopenia (looking for platelet clots)
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2
Q

Thrombocytosis

Etiology

A

Reactive to: infection, post-surgery, splenectomy, malignancy, acute blood loss;
Myeloproliferative disorders

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3
Q

Pseudothrombocytopenia

Etiology

A
  1. Incomplete mixing of blood collection tubes;

2. EDTA dependent agglutinins

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4
Q

Pseudothrombocytopenia

How to identify?

A

Check peripheral blood smear to find platelet clots

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5
Q

What is the lifespan of plt?

A

10 days

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6
Q

Thrombocytopenia

Causes of plt underproduction

A

Marrow failure
Marrow invasion
Marrow injury
Congenital

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7
Q

Thrombocytopenia
Causes of plt underproduction
Marrow failure

A

Aplastic anemia
Myelodysplasia
Vitamin B12/folate deficiency
Fanconi anemia

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8
Q

Thrombocytopenia
Causes of plt underproduction
Marrow invasion

A

Leukemia
Tumors
Granulomatous disease (sarcoidosis)
Fibrosis (primary myelofibrosis)

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9
Q

Thrombocytopenia
Causes of plt underproduction
Marrow injury

A

Drugs (especially alcohol, chemo)
Radiation
Infections (HCV, HIV)

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10
Q

Thrombocytopenia
Causes of plt underproduction
Congenital

A
Wiskott-Aldrich syndrome
Thrombocytopenia absent radius (TAR) syndrome
May-Hegglin anomaly
Gray platelet syndrome
Bernard-Soulier syndrome
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11
Q

Thrombocytopenia
Platelet sequestration
Will thrombopoietin synthesis increase in the setting of splenic sequestration?

A

No.

Even it is sequested, thrombopoietin is still negatively controlled by plt mass.

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12
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
Pathophysiology

A

Microangiopathic

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13
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
3 categories

A

DIC
TTP
HUS

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14
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP-pathophysiology?

A

Abnormal activation of plt and endothelial cells.

Deficiency in the protease ADAMTS-13

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15
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
What is the causes of deficiency of protease ADAMTS-13

A

Congential;

Produced by an autoantibody

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16
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
What is the consequence of protease ADAMTS-13 deficiency?

A

Accumulation of clumps of ultra-large-molecular-weight vWF multimers–>microvascular occusion–>thrombocytopnenia

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17
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
What are the triggers of TTP?

A

Medication

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18
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
What medications can trigger TTP?

A

Quinine
Ticlopidine
Cyclosporine
Gemcitabine

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19
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
What are the lab findings?

A
Thrombocytopenia
Schistocytes on peripheral blood smear
Elevated LDH and bilirubin
Low haptoglobin
Low RBC
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20
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
Sx:

A
Easy bruising;
Fever
Kidney disease
Neurologica changes
Abdominal pain
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21
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
Treatment?

A

Plasma exchange

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22
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
TTP
Can you transfuse plt?

A

NO!

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23
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
HUS
What are the 2 types?

A

Typical - induced by diarrhea or infection

Atypical - not related to diarrhea episodes

24
Q

Thrombocytopenia
Non-immune-mediated thrombocytopenia
HUS
Typical HUS- infections?

A

E.Coli O157:H7

Shiga toxin producing bacteria

25
Thrombocytopenia Non-immune-mediated thrombocytopenia HUS Treatment for typical HUS-infection?
Plasma exchange
26
Thrombocytopenia Non-immune-mediated thrombocytopenia Atypical HUS Causes
Caused by congenital syndrome | Overwhelming complement activation
27
Thrombocytopenia Non-immune-mediated thrombocytopenia Atypical HUS treatment?
Eculizumab
28
Thrombocytopenia Non-immune-mediated thrombocytopenia Atypcial HUS Mechanism of eculizumab?
Monoclonal antibody directed against terminal components of the complement cascade.
29
Thrombocytopenia Immune-mediated thrombocytopenia ITP Will you do antiplatelet antibody test?
NO! | Low sensitivity and low specificity
30
Thrombocytopenia Immune-mediated thrombocytopenia ITP What are the causes of ITP
``` Medications; CLL HL NHL Viral illness (HIV. HCV) ```
31
Thrombocytopenia Immune-mediated thrombocytopenia ITP What are the lab findings if ITP?
Normal Hgb and WBC Large plt on peripheral blood smear No schistocyte of peripheral blood smear R/o hyper/hypo thyroidism
32
Thrombocytopenia Immune-mediated thrombocytopenia ITP When to treat?
If plt<30 or bleeding
33
Thrombocytopenia Immune-mediated thrombocytopenia ITP What to treat?
Prednisone 1mg/kg followed by slow taper over the course of weeks
34
Thrombocytopenia Immune-mediated thrombocytopenia ITP What if not responding or relapse after steroids taper?
IVIG and anti-D immune globulin
35
Thrombocytopenia Immune-mediated thrombocytopenia ITP When to start Anti-D immune globulin
Only in Rh-positive patients
36
Thrombocytopenia Immune-mediated thrombocytopenia ITP What are the 2nd line therapies
Rituximab Splenectomy Use of thrombopoietin mimetic agents
37
Thrombocytopenia Immune-mediated thrombocytopenia ITP How to treat if plt<10?
IVIG+ steroids+ transfusion
38
Thrombocytopenia Immune-mediated thrombocytopenia HIT (Heparin-induced thrombocytopenia) Pathophysiology?
Antigen: complex between flatelet factor (PF4) and heparin; Antibody: activate PF-4 and heparin through Fc receptor on platelet
39
Thrombocytopenia Immune-mediated thrombocytopenia HIT Sx:
Plt decrease by 50% 5-10 days after treatment of heparin; | Could also be thrombosis
40
Thrombocytopenia Immune-mediated thrombocytopenia HIT Diagnostic test?
``` Serologic testing (ELISA): Functional assay: serotonin release assay (gold standard) ```
41
Thrombocytopenia Immune-mediated thrombocytopenia HIT Management
Stop Heparin, start argatroban; Send serologic testing and functional assay; Baseline doppler ultrasound of all 4 extremities
42
Thrombocytopenia Immune-mediated thrombocytopenia HIT Predicting HIT pretest probability
``` 4Ts Thrombocytopnenia Timing of platelet count decrease Thrombosis other sequelae Other causes for thrombocytopenia ```
43
Platelet function test | When to do the test?
If abnormal bleeding in those plt count, PT and PTT are normal
44
Platelet dysfunction | What are the congenital platelet defects?
``` Glanzmann thrombasthenia; Bernard-Soulier syndrome Wiskott-Aldrich syndrome Gray pletelet syndrome Storage pool disease ```
45
Platelet dysfunction Glanzmann thrombasthenia Mechanism
Defect in glycoprotein IIb-IIIa | Severe
46
Platelet dysfunction Glanzmann thrombasthenia Treatment
Platelets or recombinant factor VIIa | e-aminocaproic acid
47
Platelet dysfunction Bernard-Soulier syndrome Mechanism
Defect in glycoprotein Ib-IX | Severe
48
Platelet dysfunction Bernard-Soulier syndrome Treatment
Platelet | e-aminocaproic acid
49
Platelet dysfunction Wiskott-Aldrich syndrome Mechanism
Triad of eczema, thrombocytopenia and immunodeficiency | Moderate
50
Platelet dysfunction Wiskott-Aldrich syndrome Treatment
Platelet | e-aminocaproic acid
51
Platelet dysfunction Gray platelet syndrome Symptoms
May develop myelofibrosis | Moderate
52
Platelet dysfunction Gray platelet syndrome Rx
Platelet | e-aminocaproic acid
53
Platelet dysfunction Storage pool disease Mechanism
Defects in the granules in platelets, lack of granular non-metabolic ADP Moderate to mild
54
Platelet dysfunction Storage pool disease Rx
Platelet e-aminocaproic acid May resonpde to desmopressin
55
Platelet dysfunction | What are the acquired platelet defects?
``` Uremia; Liver disease Myeloproliferative neoplasms; Post-cardiac bypass Antiplatelet drugs; IIb-IIIa inhibitors Aspirin Clopidogrel NSAIDs; Other drugs and herbs (beta-lactams, vitamin E, ginkgo, turmeric, garlic, Chinese ree fungus) ```
56
Platelet dysfunction | Are aspirin and clopidogrel induced thrombopenia reversible?
No. Irreversible.