Science digest

Are all D-dimer assays created equal? D-dimer is an important laboratory test for suspected venous thromboembolism. Formed as degradation products of blood coagulation, by the dissolution of the fibrin mesh. In cases of venous thromboembolism, D-dimer results May be elevated up to 20 days following the event, with the most useful window being up to 11 days after the event. Laboratory reports of results must also consider that D-dimer results increase with age as an additional variable. D-dimer assay kits are available from several manufacturers which May result in variation in the end results. A recently published paper by investigators in New Zealand (1) demonstrated the importance of understanding the relationship for D-dimer reporting from different manufacturer's assay kits. The authors undertook a retrospective analysis of two D-dimer assays (INNOVANCE D-dimer and STA-Liatest) comparing the methods used by a community-based centre and a hospital laboratory setting respectively. A direct comparison of matched samples from 805 patients revealed that the INNOVANCE D-dimer test gave higher results than the Liatest and the former was suspected to have interference from heterophile antibodies. Result discrepancies occurred in 22% of the patients' samples and the authors discussed that the lack of international standardisation compounds the problems of D-dimer result reporting with variation between commercial D-dimer assay kits