Effects of pH and concentration of sodium citrate anticoagulant on platelet aggregation measured by light transmission aggregometry induced by adenosine diphosphate.

The 2013 ISTH-SSC guidelines for the standardization of light transmission aggregometry (LTA) were largely based on expert consensus, as studies directly comparing LTA methodologies were lacking. We experimentally tested the cogency of ISTH-SSC recommendations pertaining to use of anticoagulant, in particular whether: (1) buffered citrate (BC) is preferable to unbuffered citrate (C); (2) the two recommended concentrations of sodium citrate (109 and 129 mM) are equivalent in terms of platelet aggregation (PA). Blood from 16 healthy volunteers was collected into BC and C (109 and 129 mM). PA was measured by LTA in platelet-rich plasma (PRP) stimulated by adenosine diphosphate (ADP) (2 µM) immediately after PRP preparation and up to 4 hr after blood collection; pH and platelet counts in PRP were measured in parallel. pH in PRP increased with time up to about 8 for all anticoagulants, although it was lower in BC than in C at all times. In BC, PA was lower at 45 min, but equivalent at all other times. PA was higher and more stable in sodium citrate 109 mM than in 129 mM at all times. The extent of PA did not change for up to 2 hr after blood collection, and subsequently dramatically decreased. In contrast with ISTH-SSC recommendations, (1) BC does not show advantages compared to C; (2) 109 mM citrate is preferable to 129 mM, because it better supports PA; and (3) LTA studies should be completed within 2 hr of blood collection, instead of the recommended 4 hr.

Usefulness of the INNOVANCE PFA P2Y test cartridge for the detection of patients with congenital defects of the platelet P2Y12 receptor for adenosine diphosphate.

INTRODUCTION: The platelet function analyzer (PFA)-100 is used in clinical practice to screen patients with bleeding diathesis and suspected defects of primary hemostasis. A new cartridge, INNOVANCE PFA P2Y, has been specifically developed to monitor patients' response to drugs inhibiting the platelet P2Y12 receptor for ADP. In this study, we compared the ability of INNOVANCE PFA P2Y to detect congenital defects of the platelet P2Y12 receptor to that of standard cartridge formulations currently in clinical use. MATERIALS AND METHODS: We studied two patients with severe P2Y12 deficiency, one patient with heterozygous P2Y12 deficiency and one with dysfunctional P2Y12 receptor. Closure times were measured using 3 cartridges: collagen/ADP, collagen/epinephrine, and INNOVANCE PFA P2Y. The results obtained in the four patients with P2Y12 defects were compared to those obtained for 20 healthy controls. RESULTS: In 2 patients with severe P2Y12 deficiency, closure times of INNOVANCE PFA P2Y and collagen/ADP cartridges were >300 s, while those of collagen/epinephrine cartridge were variable (186s and >300 s). In the patient with dysfunctional P2Y12, closure time of INNOVANCE PFA P2Y was >300 s, while closure times of collagen/ADP and collagen/epinephrine were normal. Closure times of all cartridges were normal in the patient with heterozygous P2Y12 deficiency. CONCLUSION: Our study provides the first evidence that INNOVANCE PFA P2Y cartridge is sensitive to congenital severe and moderate defects of the platelet P2Y12 receptors.