scope:

This document provides general recommendations for assaying the coagulant activity of all of the intrinsic, extrinsic, and common coagulation factors except fibrinogen. It confines itself to one-stage assays that measure the ability of test plasma to correct the APTT or PT of factor-deficient plasma. This guideline does not cover the measurement of factor activity by its effects on synthetic, chromogenic substrates nor does it include the assessment of factor levels by their antigenic properties. H48-A describes log-linear and log-log transformations of data to achieve reference curve linearity but does not embody more complex mathematical transformations.