Activated partial thromboplastin time (aPTT)

Last edited and medically reviewed by Alaric Steinmetz on 09.02.2023

Activated partial thromboplastin time (aPTT, activated Partial Thromboplastin Time) is a test used to monitor the intrinsic coagulation pathway. It is an important monitoring parameter during heparin or thrombolytic therapy, as well as for detecting coagulation disorders. The aPTT is measured in seconds and can be reported as a ratio compared with healthy control samples.

aPTT Ratio Ranges

Normal aPTT Ratio	Subtherapeutic aPTT Ratio¹	Therapeutic aPTT Ratio [^2]
1	1 to 2	>2

References

Bates, Shannon M., et al. "Use of a fixed activated partial thromboplastin time ratio to establish a therapeutic range for unfractionated heparin." Archives of internal medicine 161.3 (2001): 385-391. ↩ ↩

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