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39 Cards in this Set
- Front
- Back
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What does Prothrombin Time test for?
What are the reagents? What's in them?
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PT Tests the adequacy of the Extrinsic pathway
Thromboplastin is the only reagent -TFIII- rabbit brain or Innovin(recombinant human tissue factor produced in E. coli) - Phospholipid (PF3 substitute) - Calcium to override sodium citrate |
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PT tests for the adequacy of what factors?
What is the reference range?
Used to monitor the affects of what type of drug?
What PT range should patients have on these drugs? |
VII, X, V, II, and I
Can't test for TF-III, Ca, PF3, or XIII
Range: 11-13 seconds
Monitors effects of oral anticoagulants Range: 20-27 seconds |
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What is the International Normalized Ratio?
Why is it used? |
It is a value calculated to standardize patient results from different labs. Different labs use different instruments and reagents generating different values
PIVKAs can affect the PT Each reagent is assigned an International Sensitivity Index by the WHO based on how sensitive it is to PIVKAs |
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What are PIVKAs? |
Proteins Induced by Vitamin K Absence or Antagonists
The magic 4 factors in an incomplete form due to the lack of vitamin K (from being on anticoagulants) |
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What is the INR formula?
What is the INR reference range? What is the therapeutic INR range? |
(Patient PT/ Normal PT) ^ISI
Range: 0.9-1.2 Therapeutic range: 2.0-3.0 |
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What does aPTT stand for? What does the aPTT test for? What are the reagents? |
Activated Partial Thromboplastin Time
Test adequacy of Intrinsic Pathway
Two reagents: Activator reagent (Actin FSL) Contact activator(celite, kailin, or ellagic acid) Phospholipid (PF3 substitute) CaCl2 |
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The aPTT tests for what factors?
What is the reference range?
The aPTT is used to monitor what therapy?
What is the therapeutic range? |
XII, XI, IX, VIII, X, V, II, I NOT- PF3, Ca, or XIII
Range: 26-36sec
Monitors effects of Heparin Therapeutic range: 2-2.5 times normal value |
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What does Thrombin Time test for?
What is the reagent?
Reference range? |
Tests adequacy of Fibrinogen
Dilute Thrombin in reagent Converts fibrinogen to fibrin
14-20 sec |
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When is a 50:50 mix performed?
What does it determine? |
Run a 50:50 mix when PT, aPTT, or TT is prolonged
Determines if abnormality is due to a factor deficiency or an inhibitor (lupus anticoagulant or specific factor inhibitor) |
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What are the two different types of Fibrinogen Assays and what do they measure? |
Immunological Fibrinogen-measures Ag -Quantitates TOTAL FIBRINOGEN (including dysfunctional) -RID or nephelometry
Fibrinogen Activity - Quantitates FUNCTIONAL FIBRINOGEN - Mechanical or photo-optical |
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How is fibrinogen activity measured? |
Same principle as TT except: -Use diluted plasma (1:10) to reduce effect of inhibitors like heparin -Results reported in mg/dL of fibrinogen |
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What are the reagents used to test fibrinogen activity? |
-Fibrinogen calibration reference -known fibrinogen conc. -used for making standard curve -Thrombin -stronger than that used in TT -Owrens Veronal Buffer -Diluent |
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What is the reference range for fibrinogen activity? |
Range: 200-450 mg/dL |
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What are FDPs?
When will the test for FDPs be positive? |
Fibrin and/or Fibrinogen Degradation Products
Test will be positive in the presence of endogenous FDPs, fibrinogen, fibrin, or FDPs formed in vitro |
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What type of tube is used to collect sample for FDP testing?
What does the tube contain?
Does the tube promote or inhibit clotting?
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TSI tube
Thrombin Trypsin Soybean Inhibitor (plasmin inhibitor)
Blood in the tube will clot immediately
Centrifuge to remove fibrin clot, serum is left containing any FDPs that were present in patient blood. No FDPs are formed in the tube. |
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What are the reagents used in the FDP-latex agglutination procedure?
What concentration can it measure? |
-Suspension of latex particles coated with anti-fibrinogen Ab -Buffer-dilutions
Can detect FDPs of 2 ug/ml. Serum must be diluted, normal levels can be 2-8 ug/ml |
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Will the FDP test be positive in fibrinolysis or fibrinogenolysis? |
Both!
Can't tell the difference between the two |
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How is the FDP test interpreted? |
If both dilutions are positive; report FDP >/=40ug/ml
If 1:5 is positive; report FDP 10-40ug/ml
If both negative; report FDP <10ug/ml
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How are D-dimers formed?
When are they formed? |
Factor XIII stabilizes fibrin polymers by covalently crosslinking D domains
Plasmin breaks down clots generating D-dimers
Present only in FIBRINOLYSIS |
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What are the D-dimer assay reagents? |
Suspension of latex particles coated with anti-D-dimer Ab
Diluent buffer |
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How is a D-dimer assay interpreted? |
Reported as the concentration of the dilution that is last to show agglutination
If no agglutination- report <0.5ug/ml
Beware of post zone phenomenon |
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When is the D-dimer test positive?
A positive D-dimer test can be positive in active cases of what syndromes? |
Positive only in fibrinolysis
Can be seen in cases of DIC, DVT, PE |
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What is a factor assay used for? |
Used to determine what factor is deficient and can determine the patient's % activity of a specific factor |
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How can a factor assay be used to determine a specific factor deficiency?
What is the most common factor deficiency? |
Use patient plasma and single factor deficient plasma and run an aPTT -If pt is deficient in specific factor, aPTT remains prolonged - If deficient in a different factor, aPTT corrects
Factor VIII is most common deficiency (Hemophilia A) |
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How can a factor assay be used to determine patient's % activity of a specific factor? |
Prepare standard curve by diluting normal plasma with single factor deficient plasma
Run aPTT on dilutions and plot seconds vs % activity 1:5=100%, 1:10=50%, 1:20= 25%
Dilute patient plasma with deficient plasma (1:5, 1:10) and run aPTT Run the aPTT and read % activity off curve (1:10 dilution must be multiplied by 2) |
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What is the reference range for the % activity factor assay? |
60-150% |
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What is the Anti-Xa assay used for? |
To monitor those on LMWH, UFH, or direct factor Xa inhibitors |
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How is the Anti-Xa assay performed? |
Mix patient plasma with reagent that contains constant amount of Xa
Inhibition of Xa is proportional to amount of antithrombotic present
Add chromogenic substrate
Uninhibited Xa will cleave substrate causing color change |
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What does the color change in an Anti-Xa assay indicate? |
Degree of color is inversely proportional to the amount of antithrombotic in sample
Increased color= less LMWH or heparin present
Decreased color= more LMWH or heparin present |
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What does RVVT stand for?
What does it test for? |
Russel Viper Venom Time
Tests the common pathway |
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What does the venom from a Russel Pit Viper do to blood?
How is the test performed? |
It directly activates factor X
Mix venom with calcium and patient PPP and record clot time |
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What is the reference range for RVVT? |
20-30 seconds |
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What does Reptilase Time test for?
What does Reptilase venom do?
What can inhibit the venom? |
Used to differentiate a lack of fibrinogen from the presence of an inhibitor
Cleaves fibrinopeptide A.
Is not inhibited by heparin and autoantibodies
Some inhibition by FDPs |
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What is the reference range of the RT test? |
16-22 seconds |
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What test is used to test the adequacy of factor XIII?
What is the procedure? |
Urea Clot Lysis (Urea solubility)
Form clot with patient PRP and Ca in GLASS tube Exogenous fibrinogen may be added if initial clot isn't forming
Add 5M urea and incubate 24hrs at 37C
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What are the possible results in a Urea CLot Lysis? |
If XIII has stabilized clot, the clot will remain after 24 hrs
If XIII is inadequate the clot will dissolve |
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What does the Euglobulin Clot Lysis measure?
What is it used to monitor? |
A qualitative measure of the patient's endogenous fibrinolytic capability
Used to monitor fibrinolytic activity of patients receiving streptokinase or urokinase
Make sure no excessive fibrinogenolysis as a result of therapy |
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What is the procedure for Euglobulin Clot Lysis? |
Euglobulin fraction of plasma is precipitated using 1% acetic acid -plasminogen, plasmin, plasmin activators, fibrinogen
Precipitate is recovered and resolubilized in buffer
Fibrinogen is clotted by adding thrombin
Clot is incubated at 37C and observed every 10 min for clot lysis |
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What is the reference range for Euglobulin Clot Lysis
If a patient has increased fibrinolytic activity will the time increase or decrease? |
> 1 hour
Increased fibrinolytic activity will be indicated by clot lysis in under an hour |
