HEMA2 W9 Laboratory Evaluation Secondary Hemostasis PDF

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HEMA2 WLABORATORY EVALUATION: SECONDARY HEMOSTASISTESTS OF PHASE II COAGULATIONCOAGULATION TEST Tests the composite action of all plasma factors acting simultaneously.  Clotting time o measure of the ability of the blood to clot and is not influenced by the platelet functions other than PF. o It a...

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HEMA2 W9 LABORATORY EVALUATION: SECONDARY HEMOSTASIS

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TESTS OF PHASE II COAGULATION  COAGULATION TEST  Tests the composite action of all plasma factors acting simultaneously.  Clotting time o measure of the ability of the blood to clot and is not influenced by the platelet functions other than PF3. o It also measures only the time required for the formation of the traces of thrombin sufficient to produce a visible clot. 

PF3 o

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Micro Methods a. Slide or Drop Method  Use for children, small drop of blood needed  Perform capillary puncture  Start timing after second drop of blood and wait for 30 sec  Check for the fibrin strand  Interval: 30 seconds b. Capillary or Dale and Laidlaw’s Method  Uses capillary tube with NO ANTICOAGULANT  Prone to skin puncture  Break every 30 seconds  Check for fibrin strand Macro Methods  Superior for there is less contamination of the plasma with tissue fluids when blood is drawn from a vein. a.

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platelet membrane protein that place an important mechanism in platelet activation. it is released in plt activation and participates in thrombin participation

Lee-White Method / Whole Blood Clotting Time  PRINCIPLE  The whole blood clotting time is the time required for freshly collected blood to form a firm clot in standardized glass tubes at 37OC. Thus, the whole blood clotting time is a measure of the integrity of the intrinsic system.  Put in a red top tube  NORMAL VALUE:  5 – 10 minutes  Advantages:  More accurate and standard method.  Test can be run with control Disadvantages:   It is also a rough method.  There can be contamination of syringe or tube.  Vigorous agitation of the tubes should be avoided as it shortens the clotting time.

Activated Coagulation Time of Whole Blood (ACT)  PRINCIPLE  The activated coagulation time of whole blood is the time necessary for fresh blood to form a clot when incubated at 37OC in the presence of “surface contact” activation. This assay, like to whole blood clotting, measures overall activity of the intrinsic clotting system.  Also checks how well the dose of Heparin is working  NORMAL VALUE:  1 – 2 minutes  if ACT is too low = clot  if ACT is too high = bleed  Therapeutic range:  Px WITH Heparin intake: 180-240 seconds  Px WITHOUT Heparin intake: 70-120 seconds  Factors that may affect your results include: 1) The effects of surgery 2) Body temperature 3) Other medicines you are taking 4) Getting IV (intravenous) fluids, which can dilute your blood 5) Platelet counts and platelet function 6) Coagulation factor deficiencies

Plasma Recalcification Time (PRT) / Plasma Clotting Time

Measure of intrinsic coagulation mechanism More sensitive method than the coagulation time of whole blood. May reveal abnormality which is not detectable by the determination of the clotting time of venous blood. NORMAL VALUE: o 90-250 seconds

Activated Recalcification Time » The activated recalcification time makes use of 0.25 M CaCl2 as activator. » Employs the use of 0.1ml of Platelet Rich Plasma (PRP) » 0.1ml of 0.025 M calcium chloride - activator » 0.1ml of 1% cellite – activator » NORMAL VALUE: o Less than 50 seconds PARTIAL THROMBOPLASTIN TIME (PTT) Simple test for the INTRINSIC and COMMON pathways of coagulation.  ACTIVATED PARTIAL TRHOMBOPLASTIN TIME (APTT)  A test for the deficiencies of factors in the INTRINSIC system. o Factor VIII o Factor IX o Factor XI o Factor XII  NORMAL VALUE: o 25 – 35 seconds DIFFERENTIAL TESTS OF ACTIVATED PARTIAL THROMBOPLASTIN TIME (DAPTT)  Used to differentiate factor deficiency and disorder of circulating anticoagulants. DIFFERENTIAL PARTIAL THROMBOPLASTIN TIME (DPTT)  Another modification of APTT which is done by mixing the patient’s plasma with: o commercially available correcting reagents o Factor VIII o Factor IX reagents.  If PROLONGED, it signifies (depending on correcting reagent used):  Hemophilia A = when PTT is corrected with Factor VIII  Hemophilia B = when PTT is corrected with Factor IX PLASMA PROTHROMBIN TIME (PROTIME)  Measures the EXTRINSIC and COMMON pathway of coagulation. It is used to monitor oral anticoagulant therapy (e.g. coumadin).  Detect o prothrombin o fibrinogen Factors V, VII and X deficiencies. o  Reagent: o thromboplastin + chloride 1.

One Stage Method of Quick (Stanley Brown Method)  PRINCIPLE: o Tissue thromboplastin and calcium added to plasma react to fibrinogen to form a clot. o The thromboplastin added to the plasma takes the place of the tissue juice formation of extrinsic thromboplastin. o The prothrombin time is therefore prolonged if there is a deficiency of Factors V, VII or X   very severe deficiency of Factor I and II.

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Two-stage Prothrombin and Proconvertin Test (Owren and Aas)  It offers a combined estimation of the levels of prothrombin and proconvertin.  Advantages:  It is more sensitive with Stanley Brown Method.  Fresh specimens are not necessary, and the method can be used for mailed samples of blood.  The method is not affected by heparin.

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Owren’s Thrombotest Method  For the control of Coumarin anticoagulant therapy  this is considered as the MOST SENSITIVE TEST.

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Fibrometer Method  It is an electromechanical semi-automated instrument that has been used extensively in one-stage prothrombin method of Quick.

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Micromethod (Pro time)  This is microtechnique employed for children and the method uses micropipettes; Uses aliquot samples  PRINCIPLE: o similar with one-stage prothrombin time or Stypven Time. Related Method – Stypven Time (Rusell’s viper venom Time)  It is used to distinguish deficiencies of Factor X and those of Factor VII (FVII is not detected).  It is also used to detect deficiencies in  Prothrombin  fibrinogen  factors V and X.  It differs from prothrombin time in that deficiencies in factor VII ARE NOT DETECTED.  Uses venom from Vipera russelli or Daboia russellii.  Uses citrated plasma  Sensitive for  factor V  factor X  

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If PT and ST is prolonged, the problem is FX. If PT is prolonged and ST is normal, the problem is FVII.

Prothrombin Activity or Index  Reported in percentage, with 100% as the maximum level.

International Normalized Ratio (INR)  This method of reporting has been proposed to monitor patients on oral anticoagulant therapy.  It is defined as the prothrombin time ratio had the test been performed using international standard thromboplastin reagent.

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REFERENCE RANGE: If >1 = increased of the capability of bleeding If...