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Heme/Lymph Exam 1 (EH) > Chapter 14: Polycythemia and Bleeding Disorders > Flashcards

Chapter 14: Polycythemia and Bleeding Disorders Flashcards

1
Q

What is the most common cause of primary polycythemia?

A

Polycythemia Vera

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2
Q

The primary pathway for the initiation of coagulation is what?

A

Tissue factor (extrinsic) pathway

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3
Q

Which test assesses the intrinsic and common clotting pathways; also monitors the treatment effect of Heparin?

A

PTT

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4
Q

Which test is used to monitor treatment effect of coumadin as well as the extrinsic and common coagulation pathways?

A

PT

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5
Q

What are the platelet counts and tests of coagulation (PT, PTT) like in bleeding disorders caused by vessel wall abnormalities?

A

Typically normal

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6
Q

Which infections are associated with vessel wall abnormalities that can cause bleeding?

A
  • Meningococcemia –> can be catastrophic if not recognized clinically
  • Septicemia + infective endocarditis
  • Rickettsioses
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7
Q

Henoch-Schonlein purpura is a cause of bleeding due to vessel wall abnormalities and is characterized by what signs/sx’s?

A
  • Purpuric rash
  • Colicky abdominal pain
  • Polyarthralgia
  • Acute glomerulonephritis
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8
Q

Serious bleeding is most often associated with what inherited disorder causing vessel wall abnormalities?

A

Hereditary hemorrhagic telangiectasia (Weber-Osler-Rendu syndrome)

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9
Q

What is the most frequent symptom/presentation of hereditary hemorrhagic telangiectasia?

A

Recurrent epistaxis

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10
Q

Which infectious agents can infect megakaryocytes leading to decreased platelet production (thrombocytopenia)?

A

HIV; one of the most common hematologic manifestations of HIV

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11
Q

How may alloantibodies against platelets be generated?

A

When platelets are transfused or cross placenta from fetus —> mother

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12
Q

What are the 2 most important non-immunologic causes of decreased platelet survival leading to thrombocytopenia?

A
  • DIC
  • Thrombotic microangiopathies (TTP and HUS)
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13
Q

Chronic immune thrombocytopenic purpura (ITP) is most commonly seen in whom?

A

Young women <40 y/o and is 3x more likely in females than males

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14
Q

What is the pathogenesis of chronic immune thrombocytopenic purpura (ITP); which antibody is most often seen?

A
  • Due to autoantibodies (IgG) against platelets
  • Anti-platelet Abs are recognized by IgG Fc receptors expressed on phagocytes —> ↑ platelet destruction
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15
Q

What is seen in the bone marrow and peripheral blood with chronic immune thrombocytopenic purpura (ITP)?

A
  • Marrow reveals moderately ↑ number of megakaryocytes
  • Peripheral blood reveals abnormally large platelets (megathrombocytes)
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16
Q

What are the clinical signs/sx’s of chronic immune thrombocytopenic purpura (ITP); often there is a history of what?

A
  • Insidious onset characterized by bleeding into the skin and mucosal surfaces
  • Cutaneous bleeding in the form of petechiae and ecchymoses
  • Often there is hx of epistaxis, easy bruising, gum bleding and hemorrhages into soft tissues w/ minor trauma
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17
Q

The thrombocytopenia of chronic immune thrombocytopenic purpura (ITP) is markedly improved following what?

A

Splenectomy

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18
Q

How is the diagnosis of chronic immune thrombocytopenic purpura (ITP) made?

A

Diagnosis of exclusion after all other causes of thrombocytopenia ruled out

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19
Q

How does acute ITP differ from chronic ITP in terms of population affected and pathogenesis?

A
  • Mainly affects children, occurring equally in males and females
  • Sx’s appear abruptly, 1-2 weeks after self-limited viral infection
  • Acute ITP, unlike chronic, is self-limited and usually spontaneously resolves within 6 months
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20
Q

Chronic ITP may sometimes first manifest with what signs/sx’s?

A

Melana, hematuria, or excessive menstrual flow

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21
Q

What are 2 serious and sometimes fatal complications of chronic ITP?

A

Subarachnoid hemorrhage and intracerebral hemorrhage

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22
Q

Which 3 drugs are most commonly indicated in causing drug-induced thrombocytopenia?

A
  • Quinine
  • Quinidine
  • Vancomycin
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23
Q

Which type of heparin-induced thrombocytopenia is most clinically significant and explain what occurs?

A
  • Type II, begins 5-14 days after initiation of therapy
  • Antibodies recognize complexes of heparin and platelet factor 4
  • Leads to activation of platelets and promotes thrombosis EVEN in the setting of thrombocytopenia
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24
Q

What are the complications which may arise with heparin-induced thrombocytopenia, type II?

A
  • Clots within large arteries may lead to vascular insufficiency and limb loss
  • Emboli from DVT’s can cause fatal pulmonary thromboembolism

*This is thrombosis occurring in the setting of thrombocytopenia, which is paradoxical to what should be happening.

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25
Explain how HIV can cause both decreased production and survival of platelets?
- **HIV** binds **CD4** and **CXCR4** on **megakarytocytes**; causing these cells to become prone to **apoptosis** and ↓ **platelet** production - **HIV** causes **B-cell hyperplasia**, predisposing to the development of **autoantibodies**, which may **opsonize** platelets, promoting their destruction
26
Which feature of TTP and HUS is not of primary importance like it is in DIC?
**Activation** of the **coagulation cascade** is **NOT** of **primary importance**; so the **PT** and **PTT** = **normal**
27
Thrombotic thrombocytopenic purpura (TTP) is due to a deficiency in what?
**ADAMTS13** (aka "**vWF metalloprotease**)
28
What is the classic pentad of findings associated with TTP?
- Fever - **Thrombocytopenia** - **Microangiopathic hemolytic anemia** - **Transient neuro deficits** - Renal failure
29
How do typical vs. atypical HUS differ from eachother?
- **Typical** is **highly** assoc. w/ ***E. coli* O157:H7** infection (**shiga-like toxin**) most commonly affecting **children/older adults** - **Atypical** is assoc. w/ **defects** in **complement factor H**, membrane **cofactor protein (CD46)** or **factor I** ---\> which normally **prevent** activation of **alternative complement** pathway
30
Bernard-Soulier Syndrome illustrates the consequences of which type of platelet dysfunction; caused by what?
- Defective **adhesion** of platelets to subendothelial matrix - **AR** inherited deficiency of platelet membrane glycoprotein complex **Ib-IX**; which is a receptor for **vWF**
31
Glanzmann Thrombasthenia illustrates the consequences of what type of platelet dysfunction; what is it due to?
- Defective **platelet aggreggation** (Ma**nn**, A**gg**) - **AR** deficiency of **glycoprotein IIb-IIIa** causing failure of **platelet aggregation** in response to **ADP, collagen**, **epinephrine**, or **thrombin**
32
What are the 2 most clinically significant **acquired** defects of platelet function?
- Ingestion of **aspirin** and other **NSAIDs**; potent **irreversible** inhibitor of COX's required for synthesis of **thromboxane A2** and **prostaglandins** - **Uremia** which involves defects in **platelet adhesion, granule secretion**, and **aggregation**
33
How do hereditary vs. acquired deficiencies of clotting factors differ in the number involved?
- **Hereditary** typically only involved **ONE** factor - **Acquired** usually involved **MULTIPLE**
34
Vitamin K deficiency results in the impaired synthesis of which 5 coagulation factors?
Factors **II, VII, IX, X** and **protein C**
35
Bleeding due to clotting factor deficiencies most often occurs into which areas of the body?
- **GI** and **urinary tracts** - **Weight-bearing** joints (**hemarthrosis**)
36
vWF stabilizes which coagulation factor?
Factor **VIII**
37
Factor VIII is an essential cofactor for?
Factor **IX**
38
Type 1,2, and 3 von Willebrand disease are associated with what type of defect in vWF?
- **Type 1** and **3** = **QUANTITATIVE** - **Type 2** = **QUALITATIVE**
39
Which is most common, type 1 or type 3 von Willebrand disease; how do they differ in pathogenesis and inheritance?
- **Type 1** = **most common**; due to **autosomal dominant** inheritance and is characterized by **mild** to **moderate vWF deficiency** - **Type 3** = autosomal **recessive** inheritance; associated w/ **very low vWF** and **severe** disease
40
What is the most common subtype of type 2 von Willebrand disease; how is it inherited and what is the pathogenesis?
- Type **2A** is **most common** and is an **autosomal dominant** disorder - **vWF** is expressed in **normal amounts**, but mutations cause defective **multimer** assembly - Associated w/ **mild** to **moderate bleeding**
41
Which type of von Willebrand disease has a marked effect on the stability of factor VIII?
Type **3**
42
What is the relationship of vWF to ADAMTS13?
**- ADAMTS13** typically **degrades** very high-molecular-weight multimers of vWF **- Absence** of **ADAMTS13** as seen in **TTP** leads to **accumulation** of these multimers in plasma promoting platelet **aggregation** and **activation**
43
Prolonged PTT can be seen in which 3 inherited deficiencies of clotting factors?
- **vWF disease** - **Hemophilia A** (Factor **VIII**) - **Hemophilia B** (Factor **IX**)
44
Hemophilia A is the most common hereditary associated with what?
**Life-threatening bleeding**
45
What is the inheritance pattern of hemophilia A and who is most affected?
**X-linked recessive** so affects **mainly** **males** and **homozygous females**
46
The most severe deficiencies associated with hemophilia A are do to what type of mutation?
**Inversion** involving the **X chromosome** --\> **NO** synthesis of **Factor VIII**
47
What are characteristic signs/sx's of symptomatic hemophilia A?
- **Easy bruising** and **massive hemorrhage** after trauma or operations - **Spontaneous hemorrhages** may occur, particularly in **joints** (**hemarthroses**) - **Recurrent** bleeding **into joints** cause **progressive deformities** that can be **crippling**
48
Which finding associated with bleeding disorders is characteristically absent in hemophilia A?
Petechiae
49
What is required for the diagnosis of hemophilia A?
**Factor VIII-specific** assays
50
Hemophilia B (Christmas Disease) is due to a deficiency in what; follows what type of inheritance?
- Deficiency in **Factor IX** - **X-linked recessive** inheritance
51
How do the lab findings for bleeding time differ between Von Willebrand disease and Hemophilia's?
- **Von Willebrand** = **prolonged** bleeding time - **Hemophilia's** = bleeding time **unaffected**
52
The best way to think about the pathogenesis of DIC is how?
**Clotting** + **bleeding** into the **microcirculation**
53
Which mediator of endothelial injury is implicated in DIC occurring with sepsis?
**TNF** induces endothelial cells to express **tissue factor** on their cell surfaces, ↓ expression of **thrombomodulin**, and upregulates expression of **adhesion** molecules
54
Which 2 types of cancer are most frequently associated with DIC?
- **Acute promyelocytic leukemia** - **Adenocarcinoma** of the **lung, pancreas**, **colon**, and **stomach**
55
The possible consequences of DIC are twofold and include what?
- **Widespread deposition** of **fibrin** within microcirculation ---\> **ischemia** + **microangiopathic hemolytic anemia** - **Consumption** of **platelets** and **clotting factors** and activation of **plasminogen**, leading to **hemorrhagic diathesis**
56
Which unusual form of DIC occurs in association with giant hemangiomas?
**Kasabach-Merritt syndrome**, where **thrombi** form within **neoplasm** because of **stasis** and **recurrent trauma** to fragile vessels
57
What is the acute vs. chronic presentation of DIC most often associated with?
- **Acute**, as seen w/ **obstetric complications** or **major trauma** is **dominated** by **bleeding diathesis** - **Chronic**, such as occurs in **cancer** pt's, tends to present w/ **thrombotic complications**
58
Severe cases of DIC can cause what in the kidney?
Bilateral renal cortical necrosis
59
What is the most common complicaton of transfusions; how does it present?
- **Febrile NON-hemolytic reaction** - **Fever + chills**, sometimes **mild dyspnea**, within **6 hours** of a transfusion of red cells or platelets
60
Allergic reactions following transfusions are most common in which patients; occurs how?
- Those w/ **IgA deficiency** **- IgG Abs** recognize **IgA** in the infused blood product
61
What are the cause of acute hemolytic reactions following blood transfusions?
**Preformed IgM** Abs against **donor red cells** that **fix complement**
62
Which test will be positive in a patient with acute hemolytic reaction following blood transfusion?
**Direct Coombs test (+)**
63
Signs/sx's of acute hemolytic reaction following transfusion; what is the underying cause of them?
- Rapid appearance of **fever + shaking chills** + **flank pain** - Due to **complement activation** - Produces **hemoglobinuria** _without_ any other sx's of **hemolytic anemia**
64
Acute hemolytic reactions following a blood transfusion most often are caused by what?
**Human error**, either pt identification or tube labeling = pt receives **ABO incompatible blood**
65
What is the cause of delayed hemolytic reactions following a transfusion?
Due to **IgG Ab's** against **red cell Ag** the patient was previously **sensitized** to
66
Which labs are indicative of delayed hemolytic reactions following transfusion?
- Direct **Coombs test (+)** - Labs typical of **hemolysis** (i.e, **low haptoglobin** and ↑ **LDH**)
67
What occurs in Transfusion-Related Acute Lung Injury (TRALI)?
**Transfused** blood product triggers activation of **neutrophils** in the **lung microvasculature**
68
Most common Ab's associated with TRALI are those that bind what; who is this most often seen in?
Abs that bind **MHC class I Ags**; often found in **multiparous women**
69
What is the presentation of TRALI like; what is seen on imaging?
- **Dramatic, rapid onset** of **respiratory failure** following transfusion - Other findings include: **fever, hypotension** and **hypoxemia** - **Bilateral pulmonary infiltrates** seen on **CXR**
70
TRALI is most likely to occur when using what transfusion products?
Those w/ **high** levels of **donor Abs** such as **fresh frozen plasma** and **platelets**
71
Significant bacterial contamination is more likely with what type of blood products?
**Platelets** (must be stored at room temp.)

Heme/Lymph Exam 1 (EH) (18 decks)

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