PT-INR TestQuick and accurate coagulation test results are vital to control excessive bleeding or bruising and assure adequate clotting time. Physicians need to constantly monitor patients on oral anticoagulant therapy (OAT) such as warfarin using advanced coagulation testing methods. OAT effects are monitored by performing two laboratory assays – the prothrombin time (PT), i.e., the time in seconds required for the blood to clot, and the international normalized ratio (INR), the formula that adjusts for differences in the coagulation reagents used so that results of PT tests are comparable.

However, experts have pointed out that several lab variables can affect PT-INR test results. These include specimen collection, sample processing, laboratory equipment or instruments used to perform the assay, and the sensitivity of the thromboplastin or coagulation reagent used to perform the PT assay.

  • The presence and concentration of exogenously added heparin, citrate, oxalate, or EDTA from blood collection devices will affect the PT time and INR value.
  • Poor sample collection and storage methods can compromise the test results.
  • The coagulation tube used has also be found to be found to be a clinically important factor causing variability in coagulation testing, for instance, glass tubes can prematurely trigger coagulation, causing in faster clotting times and lower INRs.
  • The presence of a lupus anticoagulant (LA) can affect the clot-based PT assay.

Timely and accurate coagulation tests are very important to monitor patients on OAT. The use of highly sensitive coagulation reagents is also critical. Take Pacific Hemostasis Activated Partial Thromboplastin Time products. They are accurate, stable, reliable and user-friendly. Pacific Hemostasis Activated Partial Thromboplastin Time reagents (APTT) are ideal when it comes to identifying acquired or congenital disorders to the intrinsic and common pathways. APTT testing is widely accepted as a method of monitoring patients on OAT such as heparin. These products can be used on manual, semi-automated, and automated coagulation analyzers.