PB1174 - Effect of haemolysis on coagulation tests as performed on HORIBA Yumizen G1550 Analyser. How HIL auto-check can help.

Background: Haemolysis may affect haemostasis tests via release of haemoglobin, intra cellular components and thromboplastic substances from damaged cells causing misleading results.

Aims: To assess acceptable values for haemolysis using the HIL module with regards to invitro haemolysis on haemostasis assays on the HORIBA Yumizen G1550.

Methods: Plasma was prepared from samples collected into 0.109M trisodium citrate (Vacutainer Plus, Becton Dickinson) by single centrifugation at 2000g for 10 mins. Haemolysed plasmas that failed automated detection (Sysmex, CS5100) and their matched repeat from the same patient, free of haemolysis and collected within 4 hours of the initial haemolysed sample were stored at -80oC. Plasmas were analysed for prothrombin time (Yumizen G PT5, Yumizen G PT5 Liq, Yumizen G PT5 Reco), activated partial thromboplastin time (Yumizen G APTT, Yumizen G APTT Liq), Fibrinogen assay (Yumizen G Fibrinogen) and DDimer assay (Yumizen G Ddi).

Results: Spontaneous haemolysis that occurred during sample collection/processing had no clinically relevant effect on PT for any tested thromboplastin or fibrinogen determination (Table 1.) However, APTT showed clinically relevant, reagent specific changes in some samples. Yumizen G APTT 16/46 >3 second decrease, 1/46 >3 second prolongation. Yumizen G APTT Liquid 6/46 >3 second decrease, 1/43 >3 second prolongation. For DDimer there was an overall increase of 0.3 ugFEU/ml, but 4/46 increased by 2.0 ugFEU/ml or more. There was no correlation between the degree of haemolysis and any changes that occurred.

Conclusion(s): Results confirm that PT and fibrinogen were not clinically significantly affected by haemolysis. The APTT of some haemolysed samples were falsely reduced. The DDimer of some haemolysed samples were significantly raised. Haemolysed samples for APTT determination and for accurate DDimer determination should be rejected. However, as haemolysed DDimer results were falsely raised, they could still be safely used for VTE exclusion. This study highlights the importance of pre-analytical HIL auto check in coagulation.