Discrepancy between antithrombin activity methods revealed in Antithrombin Stockholm: do factor Xa–based methods overestimate antithrombin activity in some patients?

Abstract
Antithrombin is a single-chain glycoprotein of 432 amino acids. It is the most important endogenous coagulation inhibitor and inhibits several coagulation factors: IXa, Xa, XIa, XIIa, and thrombin (of which the inhibition of thrombin probably is the most important). In 1992 Blajchman et al[1][1]