Heparin contamination in blood samples may cause false prolongation of activated partial thromboplastin time (aPTT) and prothrombin time results. Polybrene can neutralize heparin, but it affects coagulation by itself.
To determine the optimal concentration of polybrene to neutralize heparin, to determine the suitable sequence of reagents for the neutralization method performed on the analyzer at the same time as prothrombin time and aPTT testing, and to detect the heparin contamination in blood samples for coagulation tests in our hospital using this method.
Various concentrations of heparin were added to 10 normal and 76 abnormal plasma samples to study the efficacy of polybrene. Two programs of reagent sequencing for aPTT with polybrene performed on the analyzer were tested. Samples suspected of heparin contamination according to our criteria were selected for neutralization during a 3-month period.
The optimal final concentration of polybrene was 25 μg/mL. Polybrene should be added after the aPTT reagent to minimize its interference effect. Even though results of prothrombin time and aPTT after neutralization did not equal those before the spike of heparin, the differences might not be clinically significant. Eighty-one of 4921 samples (1.6%) were selected for aPTT with the neutralization method, and the detection rate of heparin contamination was 84% (68 of 81), giving an overall incidence of 1.4% (68 of 4921).
This method is inexpensive and can be performed rapidly with prothrombin time and aPTT on the automated analyzer, which makes it easy to practice with no need for extra plasma volumes.