BackgroundPlatelet reactivity assessment is an important tool in both the causal determination of bleeding diathesis as well as in the evaluation of the efficacy of anti-platelet therapy in patients at risk of thrombosis. Sodium citrate is the most widely used anticoagulant for hemostasis investigations. However, some doubt exists over the suitability of sodium citrate in platelet function testing. Hirudin has been suggested as a superior replacement. Nevertheless, only 1 study compared citrated and hirudin treated samples with light transmission aggregometry. Therefore, limited evidence exists to conclusively prove the supremacy of hirudin over sodium citrate in light transmission aggregometry. The aim of our study was to compare citrated and hirudin treated samples, collected in commercially available blood collection tubes, using the 5 most common agonists, with light transmission aggregometry.Material/MethodsBlood was obtained from 20 healthy volunteers. Platelet counts were performed on platelet-rich plasma. Light transmission aggregometry was performed within 4 h of sample collection using ADP, collagen, arachidonic acid, epinephrine, and ristocetin as agonists.ResultsPlatelet counts for the respective anticoagulants did not differ significantly. ADP-induced aggregation was comparable between the samples. However, among all the agonists, hirudin-treated platelets had significantly weaker aggregatory responses.ConclusionsCommercially available sodium citrate should remain the anticoagulant of choice for routine platelet function testing in our setting. However, the time limitation associated with the use of sodium citrate in platelet function testing remains a concern. Thus, alternative anticoagulants should still be explored.