Effect of heparin-binding to thrombin on thrombin activity measured with a chromogenic substrate

Newer Synthetic Peptide Substrates in Coagulation Testing: Some Practical Considerations for Automated Methods

“…Since the first report of an amidolytic assay for heparin, many different variations of this assay have become available. 2,24,31,42,43 Although reliable in quantitating the absolute amounts of heparin in USP and international units per milliliter, most of these assays do not truly reflect the in vivo anti coagulant effect of heparin. In addition, these assays do not correlate with other assays used to monitor heparin therapy.…”