Routine Tests of Hemostatic Function

74 "Clotbusters" Routine Tests of ~ Streptokinase (commercial) Hemostatic Function 1_ Urokinase (commercial) PROTHROMBIN TIME (PT)...

74 "Clotbusters" Routine Tests of ~ Streptokinase (commercial) Hemostatic Function 1_ Urokinase (commercial) PROTHROMBIN TIME (PT) 1. Screen for extrinsic & common ~ Tissue plasminogen activator (commercial pathways and in vivo) 2. Measures factors I , II, V, VII and X 3. Monitors oral anticoagulants (warfarin, coumarin, dicoumarol) 4. Reagent - tissue thromboplastin & Role of Thrombin, Pll18lDia CaC12 and Fibrin in Hemostasis- 5. Sen sitive to Vitamin K factors 6. International normalized ratio: INR Specimen Collection/Handling l. Sodium citrate 3.2% (Ca++ is necessary INR = (. patient result }ISi for both coagulation and platelet aggregation studies) \ mean of reference range (ISi = International Sensitivity Index from manufacturer) 2. Whole blood - anticoagulant ratio = 9: 1 7. Reference range = < 13 seconds 3. Use plastic tubes or siliconized a. Therapeutic goal: INR 2.0 - 3.5 glassware (glass activates factor XII ACTIVATED PARTIAL THROMBOPLASTIN TIME (APTT) and platelets will adhere to glass). 1. Screen for intrinsi c & common 4. Coagulation samples can now be drawn pathways first when u sing evacuated tubes ( vacutainers). Historical r eports of 2. Measures all factors except VII and contamination with tissue XIII thromboplastin during collection a r e unfounded. 3. Monitors heparin therapy 5. Hemolyzed samples should NOT be 4. Reagents - activator (kaolin, celite or u sed for platelet aggregation studies ellagic acid), platelet phospholipid (PL) (red cells contain ADP). & CaC12 6. Lipemic samples may cause problems with coagulation and aggregation studies (may obscure changes in optical density). Anticoagulant Used for REMEMBER! Coagulation Studies Monitoring by PT and APTT APTT=2 T's Together Remind You of an "H"=Heparin Ratio of Anticoasu]ant : Blood PT=Coumarin· Vitamin KFactors  75 5. Reference range = 20 - 40 seconds a. Therapeutic goal: 1.5-2.5 times "normal" or u se Heparin Response Curve FIBRINOGEN ASSAY Correlate Conditions with 1. Quantitative measure of Factor I Bleeding Time Results 2. Reference range= 200-400 mg/ell 3. Anemia and hypofibrinogenemia t clot THROMBIN TIME (71) r etraction 1. Does NOT measure defects in intrinsic/ extrinsic pathways 4. Rapid dissolution of clot indicates ,t. fibrinolytic activity (example= DIC) 5. Glanzmann Thromhasthenia - no clot r etraction Special Tests of Hemostatic Function PLATELET AGGREGATION 2. Affected b y t fihrinogen levels and 1. Necessar y for platelets to stick to each presence of heparin and other anti- other thromhins 2. In vivo aggregating agents 3. Reference range =< 20 seconds a. ADP b. Collagen BLEEDING TIME c. Epinephrine 1. Historically measured platelet function d. Thromhin and numbers hut generally replaced by e. Serotonin PFA f. Arachidonic acid g. Ristocetin PLATELET FUNCTION ASSAY (PFA TEST) h. Snake venom 1. Measures platelet function with 1. Antigen-antibody complexes collagen, ADP and epinepherine J· Fibrin degradation products (FDPs) 2. Sensitive to aspirin, vWD , and ADP 3. In vitro aggregating agents receptor problems a. ADP b. Collagen 3. Replaces the bleeding time as a scr een c. Ristocetin d. Epinephrine CLOT RETRACTION e. Thromhin 1. Evaluates platelet function, fibrinogen , f. Arachidonic acid red cell volume and fibrinolytic activity 4. Measured with photo-optics 2. Abnormal if Elatelet count