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Heparin-induced Thrombocytopenia: The PF4 Assay

I had a question on HIT testing back in early August that I lost the thread on, but here is a comment on the HIT assay from Dana Haas, St. Luke’s Episcopal Hospital, Houston, TX that I think answers the question. This came, with Dana’s permission, from  Pat Letendre’s Medlab list.

Initially when my institution started doing the PF4 assay, we used the GTI polyclonal assay (this is about 10 years ago), but had problems, so we switched to the Stago kit.  Our policy is if the test is positive, we send it out for SRA for confirmation.  We found a tremendous number of false positives with the Stago kit; also it had a floating positive cut-off as opposed to a set positive cut-off.

Now that GTI has come out with the IgG kit (positive OD >0.4), we have used that for over 3 years, and our false positive rate has dropped tremendously.  When I went to ISTH in Boston last year, I found out that Hyphen also has a PF4 kit and their positive cut-off of 0.5 was what all of the speakers were using for their talks, but I have not used that kit.

Comments (1)
Apr 6, 2011 12:17pm

Here is the link for Hyphen BioMed’s HIT kits. Hyphen BioMe
Here is the link for Hyphen BioMed’s HIT kits. Hyphen BioMed’s HIT IgG was the first kit 510K cleared by FDA.

ZYMUTEST HIA kits offer a range of immuno-assays designed for testing heparin dependent antibodies, involved in the development of Heparin Induced Thrombocytopenia (HIT) or Heparin Induced Thrombocytopenia and Thrombosis (HITT). ZYMUTEST HIA, IGAM (ARK040D) measures the total antibodies, offering the highest sensitivity as all isotypes are detected. It is the preferred assay when an early detection of heparin dependent antibodies is required for assessing the development risk of HIT/HITT. ZYMUTEST HIA, IgG (ARK040A) measures only the IgG isotype, which is reported as being the most associated with the clinical complications of heparin dependent antibodies (HIT/HITT), allowing confirmation of the diagnosis of HIT/HITT or its clinical suspicion. However, some cases associated with only IgM and/or IgA isotypes can be missed. ZYMUTEST HIA, IgG, IgM and IgA (ARK040E) is designed for the full isotyping of heparin dependent antibodies, applications to characterize isotype distribution in patients with a risk or a suspicion of HIT/HITT, or for research investigations. ZYMUTEST.
Zymutest HIA IgGAM and Zymutest HIA IgG are now 510k cleared for in vitro medical diagnostic testing.

These kits are only sold by Aniara Diagnostica in North America.

Jonas Kingo

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