From Activated Partial Thromboplastin Time to Antifactor Xa and Back Again

Am J Clin Pathol. 2022 Mar 3;157(3):321-327. doi: 10.1093/ajcp/aqab135.

Abstract

Objectives: Monitoring is essential to safe anticoagulation prescribing and requires close collaboration among pathologists, clinicians, and pharmacists.

Methods: We describe our experience in the evolving strategy for laboratory testing of unfractionated heparin (UFH).

Results: An intrainstitutional investigation revealed significant discordance between activated partial thromboplastin time (aPTT) and antifactor Xa (anti-Xa) assays, prompting a transition from the former to the latter in 2013. With the increasing use of oral factor Xa inhibitors (eg, apixaban, rivaroxaban, edoxaban, betrixaban), which interfere with the anti-Xa assay, we adapted our protocol again to incorporate aPTT in patients admitted on oral Xa inhibitors who require transition to UFH.

Conclusions: Our experience demonstrates key challenges in anticoagulation and highlights the importance of clinical pathologists in helping health systems adapt to the changing anticoagulation landscape.

Keywords: Anticoagulation; Direct oral anticoagulants; Heparin.

MeSH terms

  • Anticoagulants* / pharmacology
  • Anticoagulants* / therapeutic use
  • Blood Coagulation
  • Drug Monitoring / methods
  • Factor Xa Inhibitors / therapeutic use
  • Heparin* / therapeutic use
  • Humans
  • Partial Thromboplastin Time

Substances

  • Anticoagulants
  • Factor Xa Inhibitors
  • Heparin