Cynthia Alejandra Pastor Alvarez: aPTT or Anti-Xa to Monitor Unfractionated Heparin?
Cynthia Alejandra Pastor Alvarez, Clinical Pathologist at Almar Laboratories of arec Tecamachalco, shared a post on LinkedIn about a recent article by Isabelle Gouin-Thibault et al., published in Journal of Thrombosis and Haemostasis.
”TTaP or anti-Xa to monitor unfractionated heparin?
Monitoring of unfractionated heparin (UFH) continues to evolve.
The 2026 SSC guideline of the International Society on Thrombosis and Haemostasis (ISTH) considers the anti-factor Xa activity as the optimal test for routine monitoring of UFH, maintaining TTaP as an acceptable alternative.
Why is it relevant to the laboratory?
The aPTT is a functional test influenced by multiple variables independent of heparin concentration, including factor VIII, lupus anticoagulant, factor deficiencies, inflammation, and the characteristics of the reagent itself.
The determination of anti-Xa provides a more direct assessment of the anticoagulant effect of UFH, with a recommended therapeutic range of 0.30–0.70 U/mL for most indications.
This does not mean that the aPTT is no longer useful. When used, each laboratory must establish and validate its own therapeutic interval according to its analytical and reactive system.
An update that once again highlights the role of the clinical laboratory not only in the generation of results, but also in the selection and standardization of the methodology that best represents the patient’s condition.
Reference: Gouin-Thibault I, et al. How to monitor and manage unfractionated heparin in practice (Part 1)? Guidance from the SSC of the ISTH. J Thromb Haemost. 2026; 24:3051–3062.
Infographic made with the support of generative AI. Scientific content reviewed based on the SSC-ISTH 2026 guideline.”
Title: How to monitor and manage unfractionated heparin in practice (Part 1)? Guidance from the SSC of the ISTH
Authors: Isabelle Gouin-Thibault, Corinne Frere, Lana A Castellucci, Jean M Connors, Adam Cuker, Jerrold H Levy, Thomas Lecompte, Francois Mullier

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