engleski

Evaluation of the Dialab APC sensitivity assay

Introduction: Activated protein C resistance (APCR) has become a well-established part of the thrombophilia screening profile in most laboratories due to a high frequency of Factor V Leiden (FVL) mutation. As several commercial assays of modified APCR (with predilution in FV deficient plasma) are now available, the goal of every coagulation laboratory is to find a sensitive and specific assay that will be suitable for routine work. Aim: The aim of our study was to evaluate the Dialab APC Sensitivity Assay for the laboratory determination of APCR in comparison with DNA analysis. Materials and methods: Plasma samples were obtained from 24 carriers of FVL (19 heterozygotes and 5 homozygotes) and 62 non-carriers, as identified by DNA analysis. Among tested patients 3 heterozygotes and 12 non-carriers were receiving OAT (INR range: 1.61-3.59). APCR was performed on BCT (Dade Behring) coagulation analyzer and the results were expressed as APC ratios. Results: By using a cut-off value of 2.1 we were able to identify all carriers of FVL. No difference in APC ratios was observed between non-carriers receiving OAT or not (p=0.71). There was no overlap of APC ratios between heterozygotes (mean: 1.80, range: 1.62-1.99) and normal controls (mean: 2.85, range: 2.18-3.37) even with elevated F VIII:C levels (181-452 %). There was a clear discrimination between heterozygotes and homozygotes (mean APC ratio: 1.39, range: 1.30-1.48) when a cut-off value of 1.5 was used. Conclusions: Based on our results this test appears to be highly sensitive and specific for the diagnosis of APCR associated with FVL. Furthermore, the test is easy to perform and fulfills the criteria for a screening assay.

evaluation; APC sensitivity assay

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