Table 1. Expected Anticoagulation Effects on Coagulation Assays.

Common classes of anticoagulants, including vitamin K antagonists (VKAs), low-molecular-weight heparin (LMWH), unfractionated heparin (UFH), anti-Xa inhibitors and anti-II inhibitors, and their effects on various coagulation assays, including activated partial thromboplastin time (aPTT), international normalized ratio (INR), Clauss Fibrinogen and anti-Xa activity. Where two arrows (↑↑) represent a significant increase above normal, one arrow (↑) represents a mild increase, and a dash (–) represents no effect.

Drug Class	aPTT	INR	Fibrinogen  (Clauss)	Anti-Xa Activity
VKA	↑/–	↑↑	–	–
LMWH	↑/–	–	–	↑↑
UFH	↑↑	–	–	↑↑
Anti-Xa inhibitors	↑/–	↑/–	–	↑↑
Anti-II inhibitors	↑↑	↑/–	–	–