Sensitivity of commercial prothrombin time reagents to detect coagulation factor deficiencies in equine plasma.

The research article focuses on assessing the sensitivity of commercial prothrombin time (PT) tests for detecting coagulation factor deficiencies in equine plasma using different reagents and test procedures. Findings showed that the sensitivity of these tests significantly depends on the type of reagent and test procedure used, with the highest sensitivity found in modified test procedures with specific sample dilutions.

Research Methodology

• This study was structured into two different experiments. Experiment 1 used a dilution series of equine pooled plasma (EPP) to assess the sensitivity of the PT tests. Experiment 2 involved testing 40 equine plasma samples with reduced activity levels of coagulation factors II, V, VII and X.
• Two different PT reagents were used – reagent 1 represented as human placental thromboplastin and reagent 2 represented as recombinant human tissue factor. These were used according to the instructions provided by their respective manufacturers, deemed as the standard test procedure, and were compared with a modified test procedure involving sample dilution and fibrinogen addition.

Key Findings

• Results indicated that the sensitivity significantly varied based on the type of reagent and test method used. Sensitivity using PT([ST]) with reagent 2 was lower (0.20) compared to when reagent 1 was used (0.65) or when the modified test was used with both reagents (between 0.60-0.75 for reagent 1 and 0.58-0.70 for reagent 2, depending on sample dilution).
• The highest sensitivity recorded was for a modified procedure utilising a sample ratio of 1:20.
• In samples where the activity of at least one coagulation factor was reduced by 20%, the sensitivity measures using PT([ST]) with reagent 2 were found to be inadequate (0.33), in contrast to the other test procedures (ranging between 0.83-0.94).
• The lower sensitivity observed corresponded to shorter time intervals between different coagulation activity levels when prepared via EPP dilution.

Conclusion

• The study concludes that an adequate sensitivity of prothrombin time measurements in equine plasma can be achieved using a standard test procedure, provided that a suitable reagent is used.