Coag Final Review

What factors are in the Intrinsic Path?

• Factor XII

• Factor XI

• Factor IX

• Factor VIII

• HMWK

What test is used for the intrinsic pathway?

What drug does it monitor?

aPTT

Heparin

What factors are in the extrinsic path?

F VII

What test is for the extrinsic path?
What does it monitor?

PT
Monitors Coumadin

What factors are in the common path?

F X

F V

Prothrombin

Fibrinogen

F XIII

What factors are Vit. K Dependent?

F XI

F VII

F X

Prothrombin

What are the contact factors

F XII

F XI

HMWK

F XII Def.

Prolonged PTT

F XI def.

Hemophilia C

Normal: Plt. count/Bleeding Time/PT

Prolonged PTT

F IX Def.

Hemophilia B

Normal: Plt Count/Bleeding Time/PT

Prolonged PTT

F VIII Def.

Hemophilia A

Normal: Plt count/Bleeding time/PTT

Prolonged: PT

F VII Def.

Vit. K def.

Normal: Plt count/Bleeding time/ PTT

Prolonged: PT

F X Def.

Vit. K Def.

Normal: Plt count/PFA

Prolonged: PT/PTT

F V Def.

Normal:" Plt count/PFA/TT

Prolonged PT/PTT

Prothrombin Def.

Normal: Plt count/PFA

Prolonged: PT/PTT

Fibrinogen Def.

Normal: Plt count/PFA

Prolonged: PT/PTT/TT

F XII Def.

Screening test= Pt. plasma + 0.025M CaCl—> 5M Urea

if dissolves in 24hrs=def.

Plt anatomy and main points

1. peripheral zone- contains GPIb-IX, GPIIb/IIa, PF3

2. Structural zone- made of contractile proteins for shape and release of granules

3. Organelles Zone- Alpha granules (PF4, b- thromboglobulin, and PDGF) and Dense bodies (Storage pool for ADP/ATP)

   1. Membranous zone- helps release chemicals, dense tubular system for storing iCal

ACT

Activated Clotting Time

Used to measure high levels of Heparin

Bleeding time

Obsolete

Prolonged= Plt function disorders, uremia, thrombocytopenia

Plt Function Analyzer/Assay

Uses Collagen/Epi and Collagen/ADP to stimulate Plt aggregation

If both are normal= No problems

If Col/Epi is abnormal and Col/ADP is normal=Aspirin Usage or True Plt defect`

VerifyNow

Cartridge test with fibrinogen, tests for aspirin, P2Y12 and GPIIb/IIa inhibitors

Whole blood Plt Aggregation

Measures Plt. aggregation and ADP release

Ristocetin Cofactor Assay

Also known as vWF activity assay

Ristocetin + Plts measures aggregation

Mixing Studies

Done after prolonged PT/PTT

Pt. plasma is mixed 1:1 with Pooled plasma

If it corrects= Factor def.

If it doesn’t correct= Factor inhibitor

Factor Assay

Used when suspected Factor Def.

Pt. plasma is mixed with pooled plasma that has all factors except suspected missing one

If PT/PTT corrects= Factor def.

If it doesn’t correct= Factor inhibitor

Thrombin Time

Tests for presence of Heparin

Thrombin + Pt. Plasma, time= how long fibrinogen takes to convert to fibrin

Quantitative Fibrinogen/Clauss Assay

Long time=Low fibrinogen= DIC/Fibrinolysis/Liver disease

Short time= High fibrinogen= Inflammation/pregnancy

Reptilase Time

Used with TT to detect Heparin contamination

Increased= dys/hypo/a- fibrinogenemia

D-Dimer

Measures Cross-linked fibrin degradation

pos= Maybe DIC

Neg= Patient doesn’t have DIC

Russell’s Vipper Venom

Directly activates F X

Confirmatory test for Lupus Ab

DRVVT- diluted= increased sensitivity

Anit Plt Drugs

Glycoprotein inhibitors- prevent plt adhesion via binding to GPIIb/IIIa

Plavix- blocks P2Y12 ADP receptor site on Plts

Aspirin- Irreversibly inhibits cyclooxygenase

Heparin

Inhibits Xa/IIa

• Unfractionated- binds PF4, requires monitoring

• LMWH- Only inactivates Xa, doesn’t require monitoring

• Synthetic LMWH- binds antithrombin and Xa, very expensive

Primary Hemostasis Steps

1. Endothelial damgage (exposes collagen, releases PAF, serotonin, thromboxane A2, TF, vWF, PAI)

2. Plts attach to collagen, change shape due to agonists

   • Strong stimulus: Dense bodies release ADP, Ca, Serotonin

   • Weak Stimulus: Alpha granules release PF4 and Plt Derived GF

3. GPIIb/IIa sites are exposed and become receptors for fibrinogen

4. Fibrinogen cross-links IIb/IIIa sites, creates plt-to-plt aggregation

5. PF3 is released, which becomes action site for coag. factors

Plt agonists

• ADP

• Epi

• Thrombin

• Collagen

• Ristocetin

• Arachidonic acid