PMID: 2483705Jan 1, 1989Paper

An improved heparin assay which is insensitive to platelet factor 4.

Folia haematologica : internationales Magazin für klinische und morphologische Blutforschung
K Fickenscher, U Buckler

Abstract

A new reagent for the determination of heparin in plasma has been developed. In the assay heparin which was bound to platelet factor 4 is also measured. That is why samples, which have to be assayed for heparin with this reagent, do not need any special pretreatment like fast and cooled processing in order to prevent release of platelet factor 4 from platelets. Heparin can be assayed in samples anticoagulated with citrate which are used routinely for the determination of other coagulation parameters like PT or aPTT. Freezing prior to the assay is possible and does not influence the result. The assay is based on the inactivation of factor Xa by antithrombin III which is catalysed by heparin or smaller fragments of it. It can therefore be used for the determination of heparins of low molecular weight, too. The sample is first mixed with AT III in order to compensate for a potentially decreased level in the probe. Then the F Xa reagent is added, which releases bound heparin from plasma proteins like platelet factor 4 by an added polysulfated dextran simultaneously to the onset of the inhibitory reaction towards F Xa. Free and secondarily released heparin are then available for determination. After a defined period of time a substr...Continue Reading

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