Simple and accessible screening method for congenital thrombopathies using an impedance haematology counter – reply: The differences between impedance aggregometry in whole blood versus aggregometry in PRP. Is there a need for caution?

Brahimi et al. in this journal formed a hypothesis that “the platelet count is underestimated, by an automated cell counter, each time platelet aggregates are present in the sample tube.” The addition of a platelet agonist to a stimulated sample tube will lead to the formation of platelet aggregates and hence to a drop in the platelet count. In the case of a hereditary platelet dysfunction, platelet aggregates cannot be formed upon addition of a platelet agonist and the platelet count will remain unchanged. The authors propose a hypothesis to develop “a more accessible screening technique for these hereditary platelet dysfunctions.” In our reply, we critically evaluate this screening method and focus on the importance of the differences between impedance aggregometry in whole blood versus aggregometry in platelet-rich plasma.