TESTS

• POCT coagulation testing includes:

  • Activated clotting time (ACT)
  • PT/INR
  • PTT & TCT
• This test assesses both extrinsic and common pathway factors

  PT
• This test assesses both intrinsic and common pathway factors

  APTT
• This test assesses fibrinogen levels; affected by heparin

  Thrombin Clotting Time (TCT)
• This test assesses fibrinogen levels and is not affected by heparin

  Reptilase time (RT)
• This test assess common pathway factors

  Stypven time (ST)
• This test assess factor XIII levels

  Duckert's test
• Refers to excessive amounts of plasminogen activators from damaged cells?

  Primary Fibrinolysis
• Refers to uncontrolled, inappropriate formation of fibrin within the blood vessels with formation of fibrin monomers/polymers plus D-Dimers

  Secondary Fibrinolysis
• Causes of Secondary Fibrinolysis

  • Infection
  • Neoplasm
  • Snake Bite
  • HTR
  • DIC
• TEST FOR PRIMARY HEMOSTASIS

  1. Platelet Count

  2. Bleeding Time

  3. Clot Retraction

  4. Platelet Aggregation
• They are difficult to count because: they easily disintegrate, small, colorless, refractile bodies, difficult to distinguish from debris, unevenly distributed in the blood, tend to attach to foreign surface, tend to clump with each other?

  Platelets
• Platelets are counted in relation to 1000 RBC in the smear, 3-10 platelets/100 RBC, NOT RELIABLE

  Indirect Method of Platelet Counting
• Direct Methods of Platelet Counting

  • Dameshek Method
  • Fonio's Method
  • Oler's Method
  • Cramer and Bannerman
• Significant bleeding occurs at a platelet count of?


  <50 x 10^3/ULP
• Reflects both platelet number and platelet functional integrity (vascular response to injury)

  Bleeding Time
• Factors affecting Bleeding Time


  • Platelet count and platelet function
  • Thickness and vascularity of the skin
  • Quality of blood vessels
  • Medications: aspirin (avoid 7 days before the test), nonsteroidal anti-inflammatory drugs (avoid 24 hours before the test)
• Methods of Bleeding Time

  • Duke Method
  • Ivy Method (Mielke's, Simplate, Template)
  • Copley-Lallitch Immersion Method
  • Aspirin Tolerance Test
• Measures the ability of the blood clot to retract

  Normal Value: 15-45 mins

  <15 thrombotic tendency

  >45 hemorrhage tendency?

  Clot Retraction
• Factors influencing Normal Clot Retraction


  • Number and activity of platelets
  • Concentration of fibrinogen
  • Packed cell volume
  • Calcium + ATP
• Methods of Clot Retraction

  • Hirseboeck Method (Castor Oil)
  • Stefanini-Dameshek Method (single test tube method)
  • Macfarlane Method
• Measures the ability of the platelet to form an aggregate in vitro

  It is also dependent on the presence of calcium ions and fibrinogen

  Platelet Aggregation
• Substances causing Platelet Aggregation

  • Collagen
  • Epinephrine
  • ADP and Thrombin
  • Collagen and Ristocetin
  • CAMP
• Methods of Platelet Aggregation

  • Platelet Aggregometer
  • Lumi aggregation Method
  • Platelet Nephelometer
• Platelet Aggregation Studies


  • ADP, Collagen, Epinephrine
  • Ristocetin
• Measures period required for free formation of blood to clot after it has been removed from the body

  Clotting Time
• Methods of Clotting Time

  • Capillary Blood Method
  • Whole Blood (Lee and White Method)
• Monitors the coagulation factors of the Extrinsic and Common pathways, used to monitor Coumarin/Coumadin/Warfarin therapy (oral anticoagulants-vitamin K antagonists)

  Prothrombin Time (PT)
• Standardized way of reporting PT to minimize the difference in PT results due to different reagent-instrument combinations

  International Normalized Ratio (INR)
• Monitors the coagulation factors of the Intrinsic and Common pathways, used to monitor Heparin therapy (HEPARIN = anti-thrombin)

  Activated Partial Thromboplastin Time (aPTT)
• Used to detect deficiencies in fibrinogen, prothrombin, and factor V and X, differs from the PT in that deficiencies in factor VII are NOT detected

  Stypven Time (Russel Viper Venom Time)
• Sensitive test in detecting heparin therapy?

  Thrombin Time
• An enzyme found in the venom of the Bothrops atrox snake, capable of converting fibrinogen to fibrin and is unaffected by heparin?

  Reptilase
• Duckert's Test/5M Urea Solubility Testdetects?


  Detects Factor XIII deficiency
• Used to identify specific factor deficiency by mixing correction reagents with patient's plasma and then performing the PT and/or aPTT

  Substitution Studies/Mixing Studies
• Test wherein clot should remain intact for approximately 48 hours at 37°C; Clot lysis or dissolution prior to 48 hours is indicative of excessive primary fibrinolysis

  Whole Blood Clot Lysis Time (WBCLT)
• Test that uses protein that precipitates when plasma is diluted with water and acidified

  It consists of plasminogen, plasmin, fibrinogen and fibrinogen activators?

  Euglobulin Clot Lysis Time
• Detects the presence of FIBRIN MONOMERS that yield PARACOAGULATION (gel-like clot)

  NORMAL: No gel formation

  ABNORMAL: Gel formation

  Protamine Sulfate Test

  plasma+Protamine Sulfate = PARACOAGULATION
• Less sensitive test but more specific than protamine sulfate.

  It detects the presence of FIBRIN MONOMERS

  No gel formation = NORMAL

  Gel formation = ABNOMAL

  Ethanol Gelation Test
• Used to evaluate specific fragments to monitor if the fibrinolytic pathway is functional

  Latex D-Dimer Test