Sunday, September 24, 2023

Selection of PT Reagent (Thromboplastin) for Coagulation Lab

  • Selection of Thromboplastin from a variety of available/offered Thromboplastin reagents is very important as the therapeutic monitoring of Warfarin depends upon INR. 
  • Single most important criterion for selection of Thromboplastin is Thromboplastin reagent with value of ISI closer to 1.0

Impact of Thromboplastin with high ISI value 

  • Small change in PT would translate into a large change in INR 
    • Large change in degree of anticoagulation or coagulation factor deficiency  
    • So, when a small change in dose or physiology of patient occurs → Therapeutic intervention becomes necessary for physician
  • Analysis becomes imprecise 
  • Coefficient of variation (CV) varies with the ISI value  
  • When the clinical decision is based on Target PT ratio, the range of PT ratio becomes small for any given value of INR 

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