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A COMPARATIVE STUDY OF LOW MOLECULAR WEIGHT HEPARIN (LMWH) MONITORING BY ANTI-XA LEVELS, OVERALL HAEMOSTASIS POTENTIAL (OHP) AND CALIBRATED AUTOMATED THROMBOGRAM (CAT) ASSAYS
Abstract number: P-T-097
Tay1 L., Aboud2 M., Ward1 C.M., Morel-Kopp1 M.C.
11Northern Blood Research Centre, The University of Sydney 22Pacific Laboratory Medicine Services (PaLMS), Dept of Haematology and Transfusion Medicine, Royal North Shore Hospital, St Leonards, Australia
How-to-cite Tay L, Aboud M, Ward CM, Morel-Kopp MC. A COMPARATIVE STUDY OF LOW MOLECULAR WEIGHT HEPARIN (LMWH) MONITORING BY ANTI-XA LEVELS, OVERALL HAEMOSTASIS POTENTIAL (OHP) AND CALIBRATED AUTOMATED THROMBOGRAM (CAT) ASSAYS. J Thromb Haemost 2007; 5 Supplement 2: P-T-097
Abstract
Introduction: LMWH is commonly used as initial anti-coagulation in patients with VTE. This treatment is monitored by anti-Xa activity, when clinically indicated. The current recommended therapeutic range for enoxaparin is 0.50 to 1.10 IU/ml. Our aim was to investigate the utility of an alternative coagulation assay to monitor the anticoagulant effect of standard doses of LMWH.
Methods: Pooled normal plasma and plasmas from healthy volunteers were spiked with enoxaparin between 0 and 1.00 IU/ml. Plasmas from 22 consecutive patients undergoing treatment with LMWH were also assayed. All samples were tested by 3 different assays: a chromogenic anti-Xa assay (Stago), CAT (Thrombinoscope) and OHP. OHP and CAT are global assays which measure two different endpoints, thrombin generation and fibrin formation respectively The trigger for the CAT assay was rTF (30pM); thrombin was used for the OHP (0.03U/ml).
Results: The correlation between anti-Xa levels and CAT parameters was excellent for the spiked enoxaparin samples (linear regression). Endogenous Thrombin Potential (ETP) values of 40 to 60% of baseline correlated with anti-Xa level of 0.59 and 0.39 IU/ml respectively. In contrast, OHP was much more sensitive to LMWH; at anti-Xa levels as low as 0.20 IU/ml, fibrin formation was completely inhibited. The curve plotting the anti-Xa levels from the 22 patient samples (0.10 to 1.11 IU/ml) against the ETP or the ETP delay was exponential and not linear. Similar results were obtained with the OHP, but complete inhibition of fibrin generation was only reached at anti-Xa level >1.00 IU/ml.
Conclusions: Individual response to LMWH showed significant variability. Overall, patients had higher ETP values than controls despite similar anti-Xa levels, consistent with a hypercoagulable state. From our experience, the CAT correlates better than the OHP with the measured anti-Xa levels, and could be an alternative tool to monitor both the therapeutic effect of LMWH and underlying hypercoagulability in patients.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number
Session Details
| Date: |
01/08/2007
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| Time: |
00:00-00:00
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| Session name: |
XXIst ISTH Congress |
| Subject: |
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| Location: |
Oxford, UK |
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