Recombinant tissue factor as substitute for conventional thromboplastin in the prothrombin time test

Area of Science:

• Hematology
• Clinical Chemistry

Background:

• Prothrombin time (PT) testing is crucial for monitoring oral anticoagulant therapy and diagnosing coagulation disorders.
• Conventional reagents like rabbit brain thromboplastin have limitations in standardization and sensitivity.

Purpose of the Study:

• To evaluate the suitability of relipidated recombinant tissue factor (r-TF) as a reagent for PT determination.
• To compare the performance of r-TF with conventional rabbit brain thromboplastin.

Main Methods:

• Calibrated r-TF against the International Reference Preparation BCT/253 to determine its International Sensitivity Index (ISI).
• Assessed r-TF's ability to detect clotting factor deficiencies in patient plasmas.
• Evaluated diagnostic accuracy in patients with liver diseases.
• Determined between-assay reproducibility using normal and abnormal PT samples.

Main Results:

• r-TF demonstrated ISI values of 0.96 (instrumental) and 1.12 (manual).
• r-TF effectively detected minor deficiencies in extrinsic and common coagulation pathway factors.
• Diagnostic accuracy for liver disease patients was comparable to conventional reagents.
• Between-assay reproducibility showed coefficients of variation of 2.3% (normal PT) and 3.9% (abnormal PT).

Conclusions:

• Relipidated r-TF is a sensitive, accurate, and reproducible reagent suitable for PT testing.
• r-TF can be used for monitoring oral anticoagulant therapy and diagnosing coagulation factor deficiencies.
• As a highly defined reagent, r-TF represents a significant advancement in PT testing standardization.