Bleeding disorders Flashcards by asw asw

what are the 3 components of the “hemostasis tripod”?

Primary Hemostasis, mediated by platelets
Coagulation, a chemical process
Vasoconstriction, a mechanical process

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Platelets adhere to disrupted vessel wall via:

A) Platelet surface membrane glycoprotein receptor Ib

B) vonWillebrand factor

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Platelets adhere to one another via:

– surface receptor glycoprotein IIb/IIIa

– fibrinogen

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what are the 2 Arachidonic acid vasoconstrictors?

– thromboxane A2

– prostaglandins (PGs).

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Platelet surface provides a site for what to occur?

– generation of thrombin

– subsequent fibrin formation

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what are the steps in the “extrinsic pathway” for clotting?

tissue factor- factor VII pathway

A) tissue factor exposed to blood
B) tissue factor forms complex with factor VII
C) factor VII activated- Factor VIIa
D) whole complex binds to factor X
E) Xa converts prothrombin (factor II) into Thrombin (IIa)
- this step requires factor V as a c-factor

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what happens in the “secondary”/alternate clotting pathway?

A) factor IX activated by tissue-factor/VIIa complex

B) factor IXa and cofactor VIII activates factor X

C) thrombin formation proceeds

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what is the 3rd coagulation pathway?

A) Thrombin itself activates factor XI

B) Factor XIa activates factor IX

C) Pathway proceeds to additional thrombin formation

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____________ is essential for the conversion of fibrinogen into fibrin

Thrombin

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what are the 4 main roles of thrombin?

1) conversion of fibrinogen into fibrin
2) Activates coagulation factors and cofactors, facilitating its own formation
3) Strong activator of platelet aggregation
4) Mediates Fibrinogen cleavage

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what are the 3 main anti-coagulation mechanisms?

1) Tissue factor pathway inhibitor (TFPI)
2) Protein C
3) Antithrombin III

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how does Protein C work?

1) Circulating protein C activated by endothelial cell-bound enzyme thrombomodulin in association with thrombin
2) Activated protein C degrades the important cofactors V and VIII
3) Activation requires an essential cofactor: protein S

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____________ will inhibit both Thrombin and factor Xa

Antithrombin III

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Antithrombin III is Strongly enhanced by presence of what molecule?

Heparin

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Fibrinolysis is mediated by what molecules? what causes their activation?

A) tPA and uPA found in endothelial cells

B) Released by several stimuli, including hypoxia, acidosis

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what are the 2 ways in which Fibrinolysis is inhibited?

1) Activator inhibitors (PAIs)

2) Circulating protease inhibitors, e.g. α2-antiplasmin

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____________ is the most common CONGENITAL coagulation DISEASE

von Willebrand Disease

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what are the 3 subtypes of von Willebrand disease?

1) Type I: reduced concentration (10-45% normal levels)
2) Type II: dysfunctional vWF
3) Type III: absent vWF (homozygous for gene defect)

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Desmopressin (DDAVP) is used to treat what types of von Willebrand disease?

Type 1

Type 2a

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how are severe forms of von Willebrand disease treated?

replacement with transfused factors

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For von Willebrand disease, treatment must continue for _______ days after surgery

4 to 7 days

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_____________ is the most commonly INHERITED coagulation DISORDER

how is this disease inherited?

Hemophilia A

Sex-linked recessive, 1 of 10,000 male births

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Hemophilia A is caused by a reduction in what molecule?

Factor VIII

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Patients with factor VIII levels greater than ___% rarely bleed spontaneously, but will have bleeding problems after surgery or trauma

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Mild Hemophilia A patients can have Factor VIII levels of ___% or less, while severe forms have less than ___%

Mild = 40% severe = less than 1%

how is Hemophilia A treated?

Mild cases: DDAVP (desmopressin) Severe cases: transfusion

Hemophilia B is similar to Hemophilia A but affects _________

factor IX

what are the 2 types of Hypercoaguable diseases?

A) Protein C Deficiency, Protein S Deficiency B) Factor V Leiden

what causes Factor V Leiden syndrome?

Polymorphic factor V which resists inactivation by activated protein C

All Hypercoaguable conditions put the patient at risk for __________

thrombosis

what clotting-related compounds are produced by the liver?

A) Liver is the source of coagulation factors B) Liver is also the source of Protein C, Protein S, and fibrinogen

Thrombocytopenia due to decreased liver function is the result of what conditions?

Result of portal hypertension and associated splenomegaly - liver failure causes drop in thrombocytes (platelets)

T/F: Clinical bleeding in patients with liver disease is often worse than predicted by INR alone

True

what is a MELD score? what is it based on?

Model for End-Stage Liver Disease (MELD) Score Formula based on: – Serum bilirubin – Serum creatinine – INR

How do MELD scores correlate to mortality?

``` – 40 or more = 71.3% – 30–39 = 52.6% – 20–29 = 19.6% – 10–19 = 6.0% – less than 9 = 1.9% ```

how can renal disease effect coagulation?

attributed to impaired platelet adhesion, aggregation, and release

______________ has been shown to correct prolonged bleeding time in patients with uremia

DDAVP (Desmopressin)

___________ is a Irreversible inhibitor of platelet membrane-associated cyclooxygenase

Aspirin - blocks the formation of thromboxane A2 - Less inhibition of other PG's

_______ days are usually required after termination of aspirin use to restore adequate platelet function and effective hemostasis

5 to 7

what are the most important adverse effects of aspirin?

1) bleeding | 2) the occurrence of hemorrhagic gastritis or even gastric ulceration

how does Clopidogrel (Plavix) function?

- Blocks the ADP receptor on the platelet

T/F: the combination of clopidogrel and aspirin was shown to be superior over aspirin alone

true | after an acute coronary event, percutaneous coronary interventions, and coronary stent placement

T/F: Clopidogrel results in MORE clinical bleeding than aspirin

true

how does Dipyramidole work?

antiplatelet effect by inhibition of phosphodiesterase

T/F: Glycoprotein Receptor IIb/IIIa Inhibitors are effective orally

False

Which vitamin-K dependent factors does Coumadin block?

factors II, VII, IX, and X

how long does it take for coumadin to reach its full effect? how long does it take for the effects of coumadin to dissipate after therapy has been stopped?

- the full effect of therapy is delayed for 2 or 3 days | - full restoration of normal coagulation after termination of Coumadin therapy requires at least 3 to 5 days

which tests are used to monitor the effects of coumadin?

PT/INR

T/F: factor Xa inhibitors do not require monitoring

true

what is the onset time for Factor Xa inhibitors? how long is their half life?

Relatively rapid onset (2-3 hours) and short half life (8-12 hours

what does Idarucizamab do?

acts as reversal agent for Dabigatran

what drug will act as a reversal agent for factor Xa inhibitors?

Andexanet Alfa - Reverses anticoagultion in less than 5 minutes

Heparin binds to ___________

antithrombin III

T/F: The anticoagulant effect of heparin may be highly variable

true

what test is used to monitor the effects of heparin?

aPTT

what are the indications for the use of Pentasaccharides?

Indicated for DVT prophylaxis or DVT/PE treatment

what is heparin-induced thrombocytopenia?

– an immunological response to heparin characterized by thrombocytopenia and thromboedema - occurs 5-7 days after first dose

what are some clinical signs that a patient may have a defect in their coagulation system?

– Abnormal bruising – Petechiae – Splenomegaly

normal PT averages ______ seconds

12 ± 2

T/F: PT times will not vary depending on laboratories

FALSE - they can differ

The PT is prolonged by deficiencies in:

``` A) factor 7 B) factor 10 C) Factor 5 D) Prothrombin E) Fibrinogen ```

The PTT measures the slower “intrinsic” pathway: normal is roughly _______ seconds

25-40

Deficiencies in factors _____ or _____ will not be detected with the PTT test

VII or XIII

which lab test is used to monitor coumadin? which one is used to monitor heparin?

A) PT/INR is for Coumadin B) aPPT is for heparin

Platelet Function Analyzer-100 (PFA-100) is used in place of what type of test?

bleeding time tests

__________________ is considered the gold standard for platelet function analysis

Platelet aggregometry (PAA)

how does dabigatran (Pradaxa) function?

direct thrombin inhibitor

name the factor Xa inhibiting drugs:

A) XARELTO (rivaroxaban) B) ELIQUIS (apixaban) C) SAVAYSA (edoxaban)

What deficiency causes the rare coumadin-induced skin necrosis?

protein C deficiency