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Disorders of Coagulation Flashcards

1
Q

What is thrombosis?

A

Inappropriate formation of platelets or fibrin clots that obstruct blood vessels

Leads to hypoxia in surrounding tissues, ischemia, and necrosis.

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2
Q

What is thrombocytosis?

A

Platelet count greater than 400 x 10^9/L

Essential thrombocythemia is a type of thrombocytosis.

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3
Q

What is the role of plasminogen activators?

A

Activates plasmin from plasminogen to break down clots

Used therapeutically for clot busting.

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4
Q

What are the conventional anticoagulant medications?

A
  • Warfarin/Coumadin
  • Heparin
  • LMWH

Each has specific uses and monitoring requirements.

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5
Q

What is the mechanism of action of Warfarin?

A

Inactivates Vitamin K, affecting factors II, VII, IX, and X

It inhibits both intrinsic and extrinsic pathways.

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6
Q

What is the effect of Heparin on thrombin?

A

Binds thrombin and blocks its effects

It amplifies antithrombin activity.

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7
Q

What is the use of protamine sulfate?

A

Reverses the effects of heparin overdose

It neutralizes any free heparin.

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8
Q

What is the role of GPIb/IIIa?

A

Links platelets together

Ib/IIIa is a glycoprotein receptor involved in platelet aggregation.

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9
Q

How can Factor Xa inhibitors be monitored?

A

Using factor Xa assay

This assay measures the activity of Factor Xa in the blood.

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10
Q

What vitamin is used to reverse the effects of Coumadin/Warfarin?

A

Vitamin K

It promotes the synthesis of clotting factors that are inhibited by Warfarin.

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11
Q

What treatment can be given for a quicker response to reverse Coumadin?

A

Fresh frozen plasma or Prothrombin complex concentrate (PCC)

These provide immediate clotting factors to counteract anticoagulation.

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12
Q

What is the normal activity range for factor assays?

A

50-150% activity

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13
Q

How is thrombin time affected by anticoagulants?

A

Increased with use of heparin anticoagulants

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14
Q

What do FDP and D-dimer indicate?

A

Breakdown of fibrin or fibrinogen into fibrin fragments and breakdown of fibrin, respectively

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15
Q

What type of samples are required for assessing fibrinolysis?

A

Platelet poor plasma – Fresh or Frozen for up to 2 weeks

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16
Q

What is the purpose of the clot solubility test?

A

To test for Factor XIII deficiency

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17
Q

What happens in the clot solubility test if Factor XIII is deficient?

A

The clot is dissolved in < 24 hours

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18
Q

What are the components of the investigation for lupus anticoagulant?

A

PTT, PT/INR, Mixing study, dRVVT

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19
Q

What is the principle behind the anti-Xa assay?

A

To monitor heparin, LMWH, fondaparinux or direct Xa inhibitors

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20
Q

What is the primary use of the dilute Russell’s Viper Venom Time (dRVVT)?

A

To investigate lupus anticoagulant

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21
Q

What are some common assays for assessing fibrinolysis?

A
  • FDP assay
  • D-dimer assay
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22
Q

What type of immunoassay can be used for rapid tests in emergency situations?

A

Latex agglutination

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23
Q

What is the basis of magnetic clot detection?

A

Detects the change in viscosity of the sample as the fibrin clot forms

A metal ball moves within the sample by magnetic force, stopping when viscosity increases due to clot formation.

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24
Q

At what wavelength is chromogenic absorbance typically measured?

A

405 nm in most cases

This wavelength is used for specific coagulation testing.

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25
What is the principle behind chromogenic testing?
Colourmetric principle of measuring absorbance is used ## Footnote Chromophore + Sample = Chromophore/sample complex and free leftover Chromophore.
26
What are the three levels of routine coagulation quality control?
* Normal * Low Abnormal * High Abnormal ## Footnote Each level controls different ranges of coagulation factors.
27
What is the primary cause of QC failure in coagulation testing?
Look at reagent as the cause first ## Footnote This includes checking for reconstitution, mixing, and expiration issues.
28
What is the best test for acute liver disease related to coagulation?
PT ## Footnote Prolongation of PT is sensitive to VII activity, which is the first factor to decrease due to its short half-life.
29
What is a common effect of renal disease on coagulation?
Platelet dysfunction is the main factor ## Footnote Uremic toxins can decrease platelet counts and activity, leading to abnormal adhesion and aggregation.
30
How does disseminated intravascular coagulation (DIC) affect clotting factors?
Consumption of all clotting factors including platelets ## Footnote It is characterized by extreme activation of coagulation.
31
What are the laboratory results characteristic of DIC?
* ↑PT * ↑aPTT * ↓Platelets * ↑D-dimer and FDPs ## Footnote Spherocytes and fragments may also be observed.
32
What distinguishes TTP from DIC?
TTP will have normal PT and aPTT; only platelets are consumed ## Footnote No clotting factors are used up in TTP.
33
What is Hemophilia A?
Deficiency of Factor VIII ## Footnote It is the most common type of hemophilia.
34
What is the inheritance pattern of Hemophilia A?
X-linked recessive ## Footnote Males are affected while females are carriers.
35
What is the treatment for Hemophilia A?
* Factor replacement therapy * DDAVP to raise VIII activity * Prophylaxis targeting ≥1% factor activity ## Footnote Treatment may vary based on inhibitor presence.
36
What is Hemophilia B also known as?
Christmas disease ## Footnote It is caused by a deficiency in Factor IX.
37
What is a common laboratory finding in Hemophilia B?
APTT – prolonged ## Footnote PT and TT remain normal.
38
What characterizes Hemophilia C?
Deficiency in Factor XI ## Footnote It is also known as Plasma Thromboplastin Antecedent (PTA) deficiency.
39
What is the treatment for Hemophilia B?
Purified factor IX concentrate, recombinant factor IX, prothrombin complex concentrate (PCC) ## Footnote Inhibitors to factor IX occur in 3% of cases, treated with PCC, recombinant VIIa, and immunosuppression.
40
What is the primary treatment for Hemophilia C?
Fresh frozen plasma (FFP), recombinant factor XI during hemostatic challenge ## Footnote Treatment is only given when needed.
41
What are nonspecific inhibitors?
Lupus anticoagulants that are not directed toward specific factors ## Footnote Often discovered through an unexpectedly prolonged PTT.
42
What is Factor V Leiden?
A mutation of factor V that results in increased resistance to inactivation by activated protein C ## Footnote This creates an inherited hypercoagulable state.
43
What is antiphospholipid syndrome?
A non-specific inhibitor targeting phospholipids that provokes blood clotting ## Footnote It can lead to increased platelet adhesion and aggregation.
44
What is the most common treatment for thrombolysis?
Plasminogen activators such as tissue plasminogen activators (t-PA) ## Footnote These are used to break down clots.
45
What is the action of Warfarin/Coumadin?
Inactivates Vitamin K, inhibiting intrinsic and extrinsic pathways ## Footnote It is used for the prevention of DVT and other clotting issues.
46
What should be monitored when a patient is on Warfarin?
INR ## Footnote Therapeutic INR should be maintained between 2.0-3.0.
47
What is the primary use of Heparin?
Quick acting anticoagulant for emergency situations ## Footnote It amplifies the activity of antithrombin.
48
What is done in the case of heparin overdose?
Stop administration and give protamine sulfate ## Footnote Monitor PTT until it is within 2 seconds of normal range.
49
What is protamine sulfate used for?
It is given to reverse heparin overdose and interacts with platelets, fibrinogen, and other clotting factors.
50
What is the primary complication associated with heparin administration?
Heparin Induced Thrombocytopenia (HIT)
51
What immune response is observed in HIT?
IgG antibodies to PF4-heparin complex lead to intravascular clots and a drop in platelet count.
52
What is the action of low molecular weight heparin (LMWH)?
LMWH mainly inhibits the intrinsic pathway and is used for breaking down thrombosis.
53
What does heparin enhance in the body?
Heparin enhances the activity of Antithrombin III (ATIII).
54
What is the mechanism of action of factor Xa inhibitors?
They inhibit factor Xa to prevent thrombin formation.
55
Which anticoagulant has a delayed action and is not suitable for emergencies?
Warfarin/Coumadin
56
What is the main concern with new generation anticoagulants?
Many do not have direct antidotes and can lead to excessive hemorrhage.
57
What laboratory test is primarily used to monitor Warfarin therapy?
INR
58
Which factors does Warfarin affect?
* II * VII * IX * X
59
What is the significance of a 30% drop in platelet count after heparin administration?
It indicates a potential HIT reaction.
60
What is the typical time frame for HIT to be observed after starting heparin treatment?
Day 4-10

Hematology 4 (12 decks)

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