D-Dimer Reports: Some Alarming Discoveries
> Thursday, July-03-2008
Presenter: John D. Olson, MD, PhD
Panelists: Dorothy Adcock Funk, MD, Kandice Kottke-Marchant, MD, PhD, Marisa B. Marques, MD
Moderator: George A. Fritsma
Precision BioLogic Laboratory Medicine Roundtable, June 20 and 21, 2008, Dartmouth, Nova Scotia
First, I’d like to thank Wendy Porteous, Steve Duff, Michael Scott, and all the Precision BioLogic Inc. participants who organized the June round-table discussion. We had the opportunity to share a number of productive ideas.
As past chair and a member of the College of American Pathologists (CAP) Coagulation Resource Committee my colleagues and I have had the opportunity to review and analyze assay quantitative D-Dimer proficiency data from CAP 2001 and 2004 surveys and presented that data at the ISTH in 2005. Publication is planned for this and other related D-Dimer data. However, what was learned is a bit alarming and is preliminarily presented here.
Silica Clotting Time (SCT) as part of the LA profile
> Thursday, May-15-2008
The silica clotting time (SCT) is a PTT-like assay that uses colloidal silica as its negatively charged particulate activator. It was first described in Chantarangkul V, Tripodi A, Arbini A, Mannucci PM. SCT as a screening and confirmatory test for detection of the lupus anticoagulants.Thromb Res 1992;67:355-65.
Chromogenix factor X assay
> Thursday, March-13-2008
In 1997, Moll and Ortel published a study concluding “lupus anticoagulants (LAs) can influence prothrombin times (PTs) and lead to INRs that do not accurately reflect the true level of [oral anticoagulant therapy (OAT)]. Use of the INR to standardize PTs is invalid for some patients with lupus anticoagulants. To prevent supratherapeutic or subtherapeutic anticoagulation, these patients must be individually monitored with a test that is insensitive to lupus anticoagulants.” They concluded: “chromogenic factor X levels and prothrombin-proconvertin times correlated well with each other and with established therapeutic ranges.” This study established an oral anticoagulant therapeutic range of 22-40% for the chromogenic factor X assay. The reference is Moll S, Ortel TL. Monitoring warfarin therapy in patients with lupus anticoagulants. Ann Intern Med 1997;127:177-85.
We expanded on the work of Moll and Ortel with two studies to support substituting the chromogenic factor X (CFX) assay for the PT/INR in the presence of LA.
