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Hematology MLT Unit 5 > Introduction to Thrombosis and Anticoagulation Therapy > Flashcards

Introduction to Thrombosis and Anticoagulation Therapy Flashcards

1
Q

What is Thrombophilia?

A
  • Environmnetal, inherited, and acquired conditions that alter coagulation.
  • Predispose a person to thrombosis
  • Hypercoagulability is synonymous w/ thrombophilia
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2
Q

What are the 2 types of thrombsis and what does each consist of?

A
  1. Arterial Thrombi - composed of PLTS, RBCs and WBCs
  2. Venous Thrombi - composed of fibrin and RBCs
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3
Q

What are the risk factors for inherited thrombosis? (8)

A
  • PAPPAHEF
    • Protein C deficiency
    • Antithrombin deficiency
    • Protien S deficieny
    • Prothrombin G20210A
    • APCR
    • Hyperhomocysteinemia
    • Elevated Factor VIII
    • Factor XII deficiency
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4
Q

What are the risk factors for aquired thrombosis? (8)

A
  • Cancer
  • Surgery
  • Immobility
  • Nephrotic syndrome
  • DIC
  • Pregnancy
  • Antiphospholipid antiodies
  • Drugs (oral contractceptives)
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5
Q

What is the main component of arterial thrombosis?

A

PLT abnormalities

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6
Q

A decrease in what can result in arterial and venous thrombosis?

A

Decrease in fibrinolysis

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7
Q

What is antithrombotic factor deficiency?

A

Inhibitors that interfere with clotting factors

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8
Q

Antithrombin neutralises what factors?

What enhances it’s activity?

A
  • IIa, IXa, Xa, XIa, XIIa (1972a)
  • Heparin
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9
Q

This protien in Vitamin K dependent, circulates as zymogen (inactivated protein) and is activated into a serine protease to inhibit clotting factors?

A

Protein C

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10
Q

This is a cofactor for protein C and is needed to activate protein C. It is also vitamin K dependent.

A

Protein S

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11
Q

Antithrombin Deficiency

What is the genetic inheritence?

What are the 2 types?

What thrombosis is it associated with?

A
  • Auto. Dom. found in 1 in 600 people
  1. Type 1: quantitatve
  2. Type II: qualitative
  • Venous thrombosis
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12
Q

Protein C Deficiency

Genetics

What type is more common?

What form has 160 mutations?

What is it associated?

A
  • Auto. Dom
  • Type I: quantitative
  • Type II: qualitative
  • Venous thromboembolism
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13
Q

Protein S Deficiency

What are it’s 2 circulating form?

A
  • Free (40%)
  • Bound to C4b-binding protein (60%)
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14
Q

Protein S Deficiency

In Type I how is protein S affected?

A

Free protein S and protein S activity are reduced to about 50% of normal value.

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15
Q

Protein S Deficiency

  • What are the 2 subtypes of Type II: qualitative disorder
A
  • Type IIa - reduced free protein S, normal total protein
  • Type IIb - both free and total protein S levels are normal.
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16
Q

Protein S Deficiency

What thrombosis is this associated with?

A

Venous thrombosis (25% arterial)

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17
Q

What is the most comon inherited cause of thrombosis?

A

Activated Protein C Resistance (Factor V Leiden)

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18
Q

ACPR (Activated Protein C Resistance) is found in what percentage of patients with recurrent thrombosis.

A

20 - 60%

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19
Q

What complications are assciated with factor V Leiden deficiency? (2)

A
  • Venous thromboembolism
  • Miscarriage
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20
Q

92% of APCR is an inherited mutation of what?

A

Factor V (Arg506GIn) (Factor V Leiden)

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21
Q

What is the second most prevalent form of hypercoagulability?

Genetics?

What increases the risk of venous thrombombolism?

A
  • Prothombin Mutation
  • G20210A
    • single point mutation
    • Auto dominant
  • Plama prothombin level >115 IU/dL
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22
Q

Hyperhomocysteinemia

  • Genetics?
  • What is homocystein?
A
  • Inherited or aquired
  • it’s an amino acid formed from coversion of methionine to cystein.
23
Q

What is Lupus Anticogulant/Antiphospholipid Syndrome?

  • What proteins are antibodies produced against (2)?
  • What age does it occur?
A

Antibodies to proteins associated with phospholipids

  • ß2-glycoprotein I
  • Apolipoprotein
  • 35 - 45
24
Q

What is Heparin Induced Thrombocytopenia (HIT)?

A
  • Immune mediated complication associated with Heparin therapy
  • Antibodies produced against heparin PLT factor IV complex causing PLT activation.
25
Q

How soon after therapy does Heparin Induced Thrombocytopenia (HIT) occur?

A

5 - 14 days after

26
Q

Heparin Induced Thrombocytopenia (HIT) may cause (5)?

A
  • Life-threatening thrombosis
  • thrombocytopenia
  • venous thrombosis more likely than arterial
  • Skin leisions
  • Heparin
27
Q

Heparin Induced Thrombocytopenia (HIT) Clinical Diagnosis.

What is seen in peripheral smear?

What develops and leads to thrombocytopenia?

A
  • MHA Schistocytes
  • Ab PF4 develops which coats PLTs then sequestered in spleen leading to thrombocytopenia.
28
Q

What are the most common acquired thrombotic disorders?

A
  • Lupus Anticoagulant/Antiphospholipid Syndrome (LAAS)
  • Heparin Induced Thrombocytopenia (HIT)
29
Q

Coagulation samples are drawn in?

A

Blue top 3.2% Sodium Citrate

30
Q

What coagulation specimens will need to be drawn differently?

A

Samples w/ Hct >60%

31
Q

What are the three types of anticoagulant drugs for treatment of thrombotic discorders?

What do they do and what do they treat?

A
  • Antiplatelet Drugs
    • Inhibit PLT activation and aggregation
    • Most effective in arterial disease
  • Anticoagulant drugs
    • Inhibit thrombin and fibrin
    • treat venous thrombosis
  • Thrombolytic Drugs
    • break down fibrin clot
32
Q

Antiplatelet Drugs: Aspirin

What does Apsirin do? and What does this prevent?

A
  • Irreversible inbitor of cyclo-oygenase enzyme (COX)
  • Inbits formation of Thromboxane A2 (TXA2) (plt activating substance released by PLTs)
33
Q
  • Dipyridimole
  • Thienopyridines
  • Ticlopidine
  • Clopidogrel

The above are all what?

A

Antiplatelet Drugs

34
Q

What is Heparin?

What does it bind to and inactivate?

A
  • Short-term anticoagulant, naturally occuring highly sulphated glycosaminoglycan
  • binds to AT and complex and inactivates thrombin and factor Xa.

intravenous/ subcutaneous administration

35
Q

Low Molecular Weight Heparin Works on which on which factor?

A

factor X

36
Q

What drug is an anticoagulant used as a long term therapy?

What factors does it inhibit?

What is its derivative?

A
  • Coumadin
  • II, VII, IX, X (1972)
  • Warfarin
37
Q

tPA, urokinase and streptokinase are what type of drug?

A

Thrombolytic drugs

38
Q

What test monitors Coumadin (warfarin) therapy?

A

PT/INR test

39
Q

What is the therapeutic range for INR?

What range of INR is at high risk of bleeding?

What is needed for prosthetic heart valves to prevent myocardial infarction?

A
  • 2.0 - 3.0 foe venous thromboembolism treatment.
  • >3.0
  • higher dose of warfarin 2.5 - 3.5 range
40
Q

What test monotors heparin therapy?

A

APTT

41
Q

What must be done before herpain therapy is started?

A

Baseline APTT and PLT count

42
Q

How often should APTT be repeated during therapy?

A

every 4 - 6 hours tp adjust dosage to therapeutic levels, 1.5 - 2.5 the mean lab reference range.

43
Q

What is evidences of heparin induced thrombocytopenia (HIT)?

A

40% reduction in PLT count from baseline

44
Q

What is the test for Activated Protein C resistance (Factor V leiden)?

What is it based on?

How is the test performed?

A
  • two part aPTT test
  • based on inhibition of factor Va by APC causing a prolonged aPTT
  • Test performed on plasma w/ or w/o APC (results expressed as ratio
    • patient aPTT+APV/patient aPTT-APC
45
Q

What is the normal ratio for the aPTT test for APCR (factor V Leiden)?

A

2.0 or greater

less than 2.0 is diagnostic

46
Q

What test is used to confirm Factor V Leiden?

A

DNA Testing

47
Q

What are the 3 assays for testing HIT?

A
  • Herparin induced PLT aggregation
  • Herparin-induced PLT ATP release by lumiaggregometry
  • C-serotonin release assy (C-SRA) by ELISA
48
Q

Lupus Anticoagulant/ Antiphospholipid Assays

What the 3 assays?

What is the mixing study procedures?

A
  • aPTT
  • Kaolin clotting time
  • Dilute Russel Viper Venom (DRVVT)
  • Px plasma mixed with normal plasma (aPTT) and test is repeated.
    • LA present mixing study not correct to normal
    • LA confirmed by adding excess PLTs
49
Q

What are the 2 coagulation methodologies?

A
  • Mechanical
  • Photo-optical
50
Q

What is the principle of mechanical methodology based on?

A

Impedence principle

  • no fibrin = no flow of curren
  • fibrin present = current flows through detection circuit and de-energizes relay
51
Q

What is the principle of photo-optical methodology based on?

A

detects change in absorbance when a clot forms

enables for large volume with high accuracy

52
Q

What are the automated and semi automated coagulation tests?

A
  • Semi-automated
    • Firometer (electromechanical)
  • Automated
    • MLA Coagulation analyzer (photo-optical)
    • Hemachron Jr. (photo-optical)
53
Q

How are PT results reported?

Normal reference range?

Critical value

A
  • in Seconds
  • 11.0 - 13.0 seconds
  • >50.0 seconds

Hematology MLT Unit 5 (5 decks)

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