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Hemostasis
Physiology: Characteristics of coagulation proteins: Contact protein, prothrombin protein, Fibrinogen
protein
Contact proteins:
Prothrombin proteins:
Fibrinogen proteins:
- Factors: XII, XI, PK
- Factors: II, VII, IX, X
- Factors: I, V, VIII, XIII
(prekallikrein)
- Vit K dependent
- Consumed during clotting (so,
- Participates in initial phase of
- NOT consumed during
not in serum)
intrinsic system
clotting (except II)
- Elevated in acute phase
- NOT consumed during clotting
(pregnancy & inflammation)
(so found in serum & plasma)
- NOT Vit K dependent
Vasoconstriction is caused by several regulatory molecules which include: thromboxane A2 and
serotonin
Warfarin is classified as a Vit K antagonist. Factors that are impacted by warfarin therapy are: II, VII, IX, X
A patient is placed on warfarin therapy, first factor that will be decreased: VII (proconvertin)
Pt with family history of bleeding presents to the ED with aPPT normal; PT elevated pt on any
medication; the factor likely to be deficient: VII
Hageman factor (XII) is involved in all of these reactions except: transformation of fibrinogen to fibrin
Most potent plasminogen activator in the contact phase of coagulation: Kallikrein
The activation of plasminogen to plasmin resulting in the degradation of fibrin occurs by: tPA
How does tissue factor pathway inhibitor inhibit coagulation: inhibition of tissue factor-factor VIIafactor Xa complex
An inhibitor of plasmin activity is: alpha-2 antiplasmin
Anti-thrombin inhibits factors: IIa and Xa
The propagation phase of the in vivo coagulation model includes: a final burst of thrombin
In the cell-based model of coagulation the intrinsic pathway operates on the: activated platelet surface
to produce burst of thrombin
A new oral anticoagulant apixaban has been given to a patient who was previously on warfarin. This
drugs directly inhibits: Xa
The anticoagulant that directly inhibits thrombin: argatroban
A pt who presents with renal impairment is being started on oral anticoagulant therapy. The DOAC that
should be avoided would be: dabigatran
In secondary hemostasis, coagulation proteins become activated to from a fibrin clot. Prior to these
proteins being activated, the inactive proenzymes are known as: zymogens
Diseases or Disorders:
Acquired disorder
Inherited disorder
Inhibitors
Hemophilia A
- pt with lupus anticoagulant may bleed due to: - Deficiency factor VIII
antibodies to prothrombin
- factor VIII pt with spontaneous bleeding: <1%
- Most common coagulation factor in which
- treat with commercial factor VIII
specific inhibitor can form: VIII
- Congenital hemophilia: found in
- Anti-Factor VIII inhibitor: Only seen in
Alloantibodies
abnormal aPTT
- A factor (X) assay done for dilutions if not
agreeing within 10% the problem: Inhibitor
Vit K deficiency:
Hemophilia B
- Deficiency factor IX
-
Factors: II, VII, IX, X
- Decrease IX associated sex-linked
2 factors that differentiate vit K def & liver
recessive disorder
disease: V and VII
- Problem with vit K deficiency: pt with
celiac disease presents occult positive
stools
- Chronic ear infections; decreased vit K
factors or: IX, II
- Amyloidosis associated factor X
Liver disease:
Von willebrand disease
- factors produce in the liver (II, V, VII, IX, X)
- abnormal all aPTT, PLT screen, ristocetin
cofactor (vWF activity)
- Liver disease pt will present DECREASE factors
- type III vWD: factor VIII level 2%, vWF activity
(II, V, VII, IX, X) and vit k factors
<1% with vWF antigen of 3%
- 2 factors that differentiate vit K def & liver
disease: V and VII
Disseminated Intravascular Coagulation (DIC):
Factor XIII deficiency
- seen in unregulated and excessive formation
- pt presents with bleeding 48 hrs after tooth
of thrombin & plasmin
extraction most
- characterized by: Hypofibrinogenemia
- common presentation: delayed bleeding
- Tests prolonged PT, aPTT; decreased
tendency
fibrinogen, PLT count; increase D-dimers; on
- if pt has factor XIII def; detect with: clot
blood smear: schistocytes
solubility in 5 molar urea solution (5M urea
- none of the above; No single test specific
test)
for DIC, but combination of tests
Lab Tests:
Specimen collection/handing
Sodium citrate for both (coag test & PLT aggregation studies)
Routine tests for Hemostatic function
Prothrombin Time (PT)
Activated Partial Thromboplastin Time (aPTT)
Fibrinogen Assay
Thrombin Time (TT)
Bleeding Time
Platelet Function Assay (PFA test)
Clot Retraction
Factor Assays
Dilute Russell’s Viper Venom test (DRVVT)
Anti-factor Xa Assay
Reptilase time
Fibrinolysis testing