Term
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Definition
adjusted partial thromboplastin time
-measures INTRINSIC pathway
"How long does plasma clot when I expoe it to Ca2+ and (-) charged surfaces?"
Process: Add PL, Ca2+, and activating surface (glass), add CaCl2, measure time to clot |
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Term
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Definition
prothrombin time
-measures EXTRINSIC pathway
"How long does plasma clot when I expose it to tissue factor (TF, aka thromboplastin)?"
Process: Incubate plasma+TF (thromboplastin), add CaCl2, measure time to clot |
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Term
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Definition
thrombin time
-measures quality of fibrinogen
If normal PTT and normal TT, the problem is in the intrinsic pathway
Process: plasma+thrombin+Ca2+; measure how long it takes for fibrinogen to convert to fibrin and form a clot |
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Term
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Definition
Great lab value for DIC, DVT/PE
product of fibrinolysis of cross-linked fibrinogen by plasmin |
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Term
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Definition
9:1 plasma:citrate ratio
-citrate chelates Ca2+ to stop clot formation before testing |
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Term
| INRhttp://www.flashcardmachine.com/my-flashcards/quick-editor.cgi# |
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Definition
patient PT/mean normal PT (prothrombin time)
-standardize PT results |
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Term
| Ddx for: High PTT, normal PT, normal platelets |
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Definition
Hemophilia (factor VIII or IX)
Deficiencies/inhib of intrinsic pathway
vWD
Heparin
HMWK deficiency (normally activates XII) |
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Term
| Ddx for: normal PTT, High PT, normal platelets |
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Definition
Factor VII deficiency
Warfarin reaction |
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Term
| Ddx for: high PTT, high PT, normal platelets |
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Definition
Vit K deficiency
II, IV, X deficiency/inhibition (common pathway)
Lack of fibrinogen |
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Term
| Ddx for: high PTT, high PT, low platelets |
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Definition
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Term
| Ddx for normal PTT, PT, and platelets |
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Definition
| Consider Factor XIII deficiency |
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Term
| Mixing studies help you determine what? Talk about the two types of mixing studies? |
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Definition
Determine deficiency (1:1 ratio of pt/normal --> normal clotting time) VS. inhibition (1:1 ratio --> normal clotting time)
-Immediate mix: check for lupus anticoagulant (fast-acting inhib) |
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Term
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Definition
aPTT (measure intrinsic pathway) performed immediately after mixing pt and normal plasma
-Check for evidence of lupus anticoagulant - fast acting inhibitor |
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Term
| Delayed (incubated) mix study |
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Definition
aPTT performed after letting mixture incubate for 1 hr
-needed to distinguish b/n factor deficiency and time-dep inhib (like factor VIII inhib) |
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Term
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Definition
| Determine levels of coagulation cascade factors |
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Term
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Definition
| look for presence of high titer factor inhibitors |
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Term
| Monitor anti-thrombotic therapies |
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Definition
1)coumadin (warfarin) (causes production of functionally-deficient Vit K-dep ptns II, VII, IX, X, C, S) - monitor using PT/INR
-measure using anti-Xa if lupus anticoagulant is present
2)Heparin - monitor using aPTT, TT, anti-Xa, activated whole blood clotting time
3)Low MW heparin - anti-Xa assay
4) Direct thrombin inhib - TT |
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Term
| Platelet testing techniques? |
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Definition
-peripheral smear
-platelet count
-template bleeding time
-platelet aggregation studies
-epinephrine
-collagen
-ADP
-Arachidonic Acid
-Ristocetin |
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Term
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Definition
Test for Bernard-Soullier syndrome
-requires GP1b and vWf for aggregation
-if absent, no aggregation |
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Term
| SRA (serotonin release assay) |
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Definition
Gold standard for Dx HIT (heparin-induced thrombocytopenia)
-serotonin is in delta granules, is a marker for platelet activation |
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