1. Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands
2. Department of Clinical Chemistry, Slotervaart Hospital, Amsterdam, The Netherlands
3. Department of Clinical Chemistry, Boven-IJ Hospital, Amsterdam
4. Department of Clinical Chemistry, Medical Center Zuiderzee, Lelystad, The Netherlands
5. Department of Clinical Chemistry, Onze Lieve Vrouwe Gasthuis, Amsterdam
6. Thrombosis Service Leiden
7. Amsterdam Thrombosis Service and Laboratory for General Practitioners
8. Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam
9. Department of Clinical Chemistry, Bronovo Hospital, The Hague, The Netherlands