Identification of and solution for false D-dimer results.

Xian‐Yan Zhang,Ying‐E Wu,Xue‐Xuan Zhang,Ying Wu,Ye‐Ru Yang,Teng‐Yi Huang,Jia‐Long Xu,Huan‐Bin Zhou

doi:10.1002/jcla.23216

Abstract

BackgroundClinically, D‐dimer (DD) levels are mainly used to exclude diseases such as deep venous thrombosis (DVT). In clinical testing, DD assays can be subjected to interference that may cause false results, which directly affect the clinical diagnosis. Our hypothesis was that the 95% confidence intervals (CIs) of the fibrin degradation product (FDP)/DD and fibrinogen (Fib)/DD ratios were used to identify these false results and corrected via multiple dilutions.MethodsIn total, 16 776 samples were divided into three groups according to the DD levels detected by Sysmex CS5100 and CA7000: Group A, DD ≥ 2.0 μg/mL fibrinogen equivalent unit (FEU); group B, 0.5 < DD < 2.0 μg/mL FEU; and group C, DD ≤ 0.5 μg/mL FEU. The 95% CIs of the FDP/DD and Fib/DD ratios were calculated. Six abnormal DD results were found according to the 95% CIs. For verification, we performed multiple dilutions, compared the results with those of other instruments, and tested the addition of heterophilic blocking reagent (HBR).ResultsThe median and 95% CI of the FDP/DD ratio were 3.76 and 2.25‐8.15 in group A, 5.63 and 2.86‐10.58 in group B, 10.23 and 0.91‐47.71 in groups C, respectively. For the Fib/DD ratio, the 95% CIs was 0.02‐2.21 in group A, 0.68‐8.15 in group B, and 3.82‐55.27 in groups C. Six abnormal results were identified after multiple dilutions, by comparison with other detection systems, and after HBR addition.ConclusionsThe FDP/DD ratio is more reliable for identifying false results. If the FDP/DD ratio falls outside the 95% CI, it should be verified by different methods.

Highlights

D-dimer is a specific degradation product derived from fibrinolytic cross-linked fibrin clots and mainly reflects fibrinolysis.[1]
We hypothesized that the 95% confidence intervals (CIs) of fibrin degradation product (FDP)/DD, Fib/DD ratio can be calculated and used to identify these false results, which will be beneficial to correct these by multiple dilutions
As a specific degradation product of cross-linked fibrin, D-dimer is a specific indicator of thrombosis and secondary fibrinolysis

Summary

| INTRODUCTION

D-dimer is a specific degradation product derived from fibrinolytic cross-linked fibrin clots and mainly reflects fibrinolysis.[1]. Thrombin acts on fibrinogen and transforms into cross-linked fibrin under the action of factor XIIIa. At the same. FDPs include fibrinogen degradation products (FgDPs) and cross-linked fibrin degradation products (FbDPs).[5,6]. The former are the products of fibrinogen (Fib) and fibrin monomer (FM), while the latter include the products of D-dimer and other fragments.[6]. With the development of modern medicine, many different D-dimer analysis methods have been developed These assays use monoclonal antibodies to detect epitopes that are present in the factor XIIIa-cross-linked fragment D domain of fibrin, including methods based on fluorescence, hemagglutination, chemiluminescence, or other techniques.[2,10,11]. Results are sometimes obtained showing normal FDP values but abnormally high D-dimer levels or low D-dimer values that are inconsistent with clinical symptoms. We hypothesized that the 95% confidence intervals (CIs) of FDP/DD, Fib/DD ratio can be calculated and used to identify these false results, which will be beneficial to correct these by multiple dilutions

| MATERIALS AND METHODS

Findings

| DISCUSSION