Aug 12 2013
From Suakimi Pouhila, Auckland District Health Board, New Zealand. We have a patient which showed high D-dimer results with Siemens’ Innovance D-dimer but normal Stago D-dimer results. Has anyone seen this before? Is this due to cross reaction with a heterophile antibody?
Hello, Suakimi Pouhila, and thank you for your question. The various monoclonal antibodies that are employed in the D-dimer assays by manufacturers all have slightly different targets, thus there are often discrepancies among results, as illustrated by the variance in results of external quality assurance programs. However, the degree of discrepancy that you describe is unusual. I’ve contacted my US acquaintances at Siemens and Stago to learn if they have any insight.
Comments (2)
Fibrinolysis
Thanks Goran
Thanks Goran
Hi Suakimi Pouhila,
Results from Innovance D-dimer started
Hi Suakimi Pouhila,
Results from Innovance D-dimer started to appear in late 2007 in the external quality assessment programs (ECAT/NASCOLA). Since then, it is easy to see, simply by plotting all the data, that Innovance D-dimer reports D-dimer values that are on average 2-fold higher than the other major D-dimer methods in the FEU-panel (e.g. BioMerieux Vidas D-dimer, Roche TinaQuant, Stago Liatest D-dimer). For some reason (unknown to me), Siemens has chosen a numerical value for their D-dimer calibrator that is 2-fold higher than what is consensus in the field. Despite this, they recommend the same cut-off value as other manufacturers. In other words, the cut-off value suggested by Siemens is only half, as compared to the other manufacturers! This will give a perfect negative predictive value in any study. However, the usefulness of D-dimer testing for the hospitals is reduced, when the number of false positives will be much higher.
If the difference you saw was larger than 2, perhaps the problem was some interference, as you suggest. I also agree with George that different mAbs can cause large difference in certain patient samples.
Best regards, Göran Aronsson