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419 Coagulation > 1st and 2nd hemostasis > Flashcards

1st and 2nd hemostasis Flashcards

1
Q

Function of Risticetin

A

Action depends on vWF and GP1b/IX/V

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2
Q

vWD

A

Corrected result after adding normal plasma

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3
Q

Bernard-Soulier syndrome

A

Genetic GP1b/IX receptor deficiency

Not corrected after adding normal plasma

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4
Q

PFA-100 specimen requirement

A

800-900 uL blood or PRP in citrate tube
PRP must be undisturbed in 30min
Whole blood: dilute 1:10 with saline and tested within 4 hrs

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5
Q

PFA-100 result reporting

A

PLT count, acitivity, vWF, hematocrit

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6
Q

PFA-100 vs Aspirin use

A

Col/Epi: Abnormal in Aspirin use, VWD, Glanz-Mann

Co/ADP: Normal in Aspirin use. Abnormal in VWD, Glanz-mann

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7
Q

PLT aggregation wave analysis for normal pt

A

ADP, Epinephrine, Ristocetin: Biphasic curve

Collagen, Arachidonic acid: Monophasic curve (only 2nd wave)

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8
Q

Arachidonic acid and U46

A

Screening for pt using aspirin last 7-10 days
U46 binds to TXA2 receptor & not affected by aspirin
- AA abnormal + U46 normal: just aspirin
- AA abnormal + U46 abnormal: receptor defect

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9
Q

Primary vs Secondary aggregation

A

Primary: Response to agonist, shaped change and small aggregation, reversible

Secondary: Response to endogenous ADP, complete aggregation, irreversible

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10
Q

Glanzmann’s thrombasthenia

A

GPIIb/IIIa deficiency —> Can’t bind to fibrinogen to make a clot —> No response to any aggregation factor, except Ristocetin

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11
Q

Prothrombin time (PT) sample requirement

A
  • Citrated patient’s PPP or control PPP
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12
Q

PT: key reagent - purpose - procedure

A
  • Thromboplastin: TF (from brain, lung, placenta) + Pl + CaCl2
  • Screening extrinsic and oral anticoagulant
  • Add reagent to PPP and record the time for fibrin formation
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13
Q

PTT: key reagent - purpose - procedure

A
  • Activated partial thromboplastin: small amount of Pl (not activate F7) + surface activator (silica, kaolin) + CaCl2
  • Screening intrinsic, inhibitor (Heparin affect APTT)
  • Add APTT reagent, add Ca, record the time for fibrin formation
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14
Q

PT abnormal

A
  • Prolonged:
    + Deficiency in VII, X, V, II, fibrinogen
    + Inhibitor
    + Dysfunctional vitamin K due to Warfarin/Coumadin
  • Shortened: Pt is on recombinant VIIa therapy
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15
Q

PTT abnormal

A

Factor deficiency (acquired, inherited)
A present of inhibitor: Lupus, FVIII inhibitor
Heparin

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16
Q

FI (Kinetic fibrinogen)

A
  • Quantitative test: low conc. of fibrinogen (diluted plasma) + high thrombin
  • Make 1:10 dilution for a standard curve. Make several dilutions –> add thrombin –> record clotting time.
17
Q

FI abnormal

A

High: inflammation, pregnant, oral contraceptive
Low: DIC, fibrinolysis, liver disease (fibrinogen made in liver)

18
Q

TT (Thrombin Clotting Time)

A
  • Qualitative test: high conc of fibrinogen (undiluted plasma) + low thrombin
  • Add thrombin –> record clotting time
19
Q

TT abnormal

A
  • Prolonged:
    + Heparin (antithrombin) or Direct thrombin inhibitor
    + Hypofibrinogen, dysfibrinogen
    + Elevated Fibrin degradation products
  • Shortened
    + Inappropriate specimen
    + Protamine sulfate infusion (used for patient after a long term heparin therapy)
20
Q

Correction the dilutions for FI standard curve

A
  • Clotting time > 50s: too little fibrinogen –> Make 1:5 instead of 1:10 dilution
  • Clotting time < 5s: too much fibrinogen –> Make 1:20, 1:40 –> Multiple with dilution factor
21
Q

International Normalized Ratio (INR)

A
  • Range: 0.8-1.3
  • Purpose: address the high level of variability in reagent sensitivity; standardize reports
  • INR = R^ISI
    + R: patient’s PT/mean normal PT
    + ISI: Int’l Sensitivity Index
22
Q

Screening F13

A
  • Purpose: Deficiency of F13 makes fibrin more soluble as a lack of cross-linking
  • Procedure: Patient’s plasma + CaCl –> clot: keep 37C in 1hr –> Add 5-6M urea (break H-bond)
  • Result: Clot dissolves within 24hrs –> Deficiency of F13 (< 1-2%)
23
Q

Mixing test

A
  • Purpose: Differentiate factor deficiency vs inhibitor’s presence
  • Procedure: Mixing pt’s plasma with normal plasma and repeat tests (PT, APTT)
    + Corrected result: Factor deficiency (compensated from normal plasma)
    + Uncorrected result: Inhibitor’s presence (inhibit the normal plasma)
24
Q

Specific Coagulation Factor Test

A
  • Purpose: Confirm the specific factor deficiency, understand the activity of a factor
  • Principle: Add diluted pt’s plasma to a known-factor deficient plasma and check if it can correct the prolong PT/APTT time
25
Q

Reptilase time

A
  • Purpose: Differentiate between dysfibrinogenemia and FDP’s presence
  • Principle: Venom act as serine protease –> cleave fibrinogen to fibrinopeptide A (instead of A&B from thrombin)
  • Reptilase is insensitive to heparin
  • Result:
    + Reptilase time > TT: Dysfibrinogenemia
    + Reptilase time < TT: Presence of fibrin degradation products
    + If Reptilase time is normal (TT: prolonged): Heparin contamination
26
Q

Diluted Russell’s viper venom test

A
  • Purpose: Activate F10 (similar method to the PT) to look for phospholipid Abs (inhibitor)
  • Procedure: Diluted venom + Pl + Ca –> Activated F10 –> Record clotting time
  • Result: prolonged –> Mixing test to R/O factor deficiency –> Add extra phospholipid: If correct, prolonged due to LA/aPL
27
Q

Kaolin Clotting time

A
  • Principle: Most sensitive test. Detects all class of inhibitors, include VIII inhibitor
  • Similar to APTT but w/o added phospholipid (rely on residual cell fragment and plasma lipids to provide phospholipid surface)
  • Kaolin: Negatively charged activator –> incubated with test plasma –> activate contact factors of the intrinsic pathway.
28
Q

Platelet Neutralization Procedure

A
  • Principle: Look for anti-phospholipid Abs by adding extra phospholipid from ruptured PLT
  • Procedure: Add pt’s PPP with ruptured PLT –> Add PTT reagent + Ca –> Record clotting time –> Compare pt’s PPP + saline vs pt’s PPP + ruptured PLT.
  • Result: Ruptured PLT mix < Saline mix –> Presence of aPL Abs
29
Q

Bethesda Titer Assay

A
  • Specific Factor Inhibitor Assay (not LA/aPL)
  • Measure F8 inhibitor
  • 1 Bethesda unit = amount of inhibitor needed to neutralize 50% of 1 unit F8:C in normal plasma at 37C
30
Q

Bethesda Procedure

A
  • Dilute patient’s plasma 1:2 - 1:1024 and mix with equal volume normal plasma for 2hrs at 37C
  • Find dilution with residual F8:C closet to 50% (30-60%)

419 Coagulation (8 decks)

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