Coagulation Tests and Disorders Flashcards
How do you collect a sample for a coagulation test?
Need a “clean stick” and avoid collection from a heparinized catheter
What tube do you use to collect a coagulation test sample?
Sodium citrate
What are the two tests that access the intrinsic/common pathway?
Activated Partial Thromboplastim Time (aPTT)
Activated Clotting Time (ACT)
Of the tests that look at the intrinsic/common pathway, which is more sensitive?
aPTT (needs ~70% deficiency to detect vs. ~95% deficiency for ACT)
How do you interpret the aPTT or ACT?
Measure time for fibrin clot formation
Prolonged time means either:
-Deficiency or inhibition of any intrinsic or common pathway factor OR
-Heparin therapy
What is the test that accesses the extrinsic/common pathway?
Prothrombin Time (PT)
How do you interpret PT results?
Prolonged time means either:
- Factor VII deficiency (good screen for Vit. K deficiency) OR
- Deficiency or inhibition of common pathway factor
What two tests do you use to access fibrinolytic activity?
Fibrin Degredation Products (FDPs)
D-dimers
How do you interpret fibrinolytic activity tests?
Increased concentration of FDPs occurs with
- Increased fibrinolysis
- Severe internal hemorrhage with fibrinolysis (also DIC)
- Decreased clearance of FDP by liver
What is the mechanism of warfarin toxicosis?
Warfarin blocks Epoxide reductase and Vitamin K reductase so Vit K can’t be reused to carboxylate/activate clotting factors 2, 7, 9, 10
What type of bleeding pattern do you see with warfarin toxicosis?
Most commonly bleed into chest
Can also bleed into joints and brain (anywhere there’s a space)
What kind of coagulation panel do you get with Warfarin toxicosis?
PT = prolonged aPTT = prolonged ACT = prolonged PIVKA = positive Platelet Count = normal
What is the mechanism of DIC?
Continued activation of coagulation and fibrinolysis
What type of bleeding patterns do you see with DIC?
Petechiae
Ecchymoses
What kind of coagulation panel do you get in the consumptive phase of DIC?
Thrombocytopenia PT = prolonged aPTT = prolonged FDP = increased D-dimers = increased
