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Updated: Aug 29, 2026
The Nijmegen Hemostasis Assay: Simultaneous Fluorogenic Measurement of Thrombin and Plasmin Generation in a Single Well
Published on: February 27, 2026
Simultaneous testing of the heparin effect on the soluble phase and platelet component of hemostasis
Laura G Melton1, Don A Gabriel, Gregory J Dehmer
1Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Background:
This study assessed the anticoagulant effect of heparin on both platelet activity and soluble phase coagulation.
Methods And Results:
Blood samples were collected from 32 patients undergoing cardiac catheterization before and 5 minutes after a heparin injection (2000 U). Activated clotting time (ACT), activated partial thromboplastin time (aPTT), and whole blood platelet aggregation [adenosine diphosphate (ADP) and collagen] were compared with the flow device variables platelet hemostasis time (PHT) and collagen-induced thrombus formation (CITF). Before heparin, all patients had a normal aPTT and all but 1 had a normal ACT. After heparin, all patients showed a prolonged aPTT and ACT. In contrast, the flow device showed considerable variability after heparin. Only 47% of patients increased both PHT and CITF above the upper limit of normal, and 13% did not prolong either. After heparin, enhanced platelet aggregation to ADP and collagen occurred in 53% and 63% of patients, respectively.
Conclusions:
Although patients seem to have an anticoagulant effect after heparin based on ACT and aPTT results, the flow device identified a lack of any hemostatic impairment in 25 to 41% of patients. These findings probably reflect the variable effect of heparin on platelet function and may explain the poor heparin effect or, alternatively, the excessive bleeding after heparin administration that occurs in some patients.
