Effects of Time-Interval since Blood Draw and of Anticoagulation on Platelet Testing (Count, Indices and Impedance Aggregometry): A Systematic Study with Blood from Healthy Volunteers

Abstract

Platelet count, indices (mean volume, young—immature platelet fraction) and aggregation are widely used laboratory parameters to investigate primary hemostasis. We performed a systematic, thorough evaluation of the influence of the time-interval since blood draw from 20 healthy individuals and of the anticoagulation of collected blood on such parameters. Blood was anticoagulated with citrate, K2-ethylenediaminetetraacetic acid (EDTA) and hirudin and analyzed 5, 30, 60, 120 and 180 min after blood draw. Multiple electrode aggregometry (MEA) was performed with either hirudin (half-diluted with NaCl) or citrate samples (half-diluted with NaCl or CaCl2 3 mM). Platelet count and indices (Sysmex XN-20) were rather stable over time with EDTA blood. MEA results were lower with citrate blood than with hirudin blood; supplementation with calcium was partially compensatory. MEA results were also lower when performed less than 30 or more than 120 min after blood draw. Platelet clumping, quantitatively estimated with microscope examination of blood smears, was more important in hirudin blood than citrate or EDTA blood and could explain some of the differences observed between preanalytical variables. The results stress once more the importance of preanalytical variables in hemostasis laboratory testing. Decision thresholds based on those tests are only applicable within specific preanalytical conditions.

Clopidogrel versus ticagrelor in the treatment of Chinese patients undergoing percutaneous coronary intervention: effects on platelet function assessed by platelet function tests and mean platelet volume

“…Of note, the swelling effect of EDTA on blood cells especially on platelet volume over the first two hours should be addressed. A significant increase in MPV could be observed in blood samples anticoagulated with EDTA over time [ 55 ]. In our study, it was recommended that MPV test should be conducted within 2 h after blood draw.…”

Pseudothrombocytopenia—A Review on Causes, Occurrence and Clinical Implications

“…Given the few hirudin-PTCP reports described and its increasing use in clinical laboratories, especially for multiple electrode aggregometry [ 129 ], the hirudin tube was also studied in this experimental protocol. This study can be added to the previous reports that showed that hirudin specimens had no advantage in correcting PTCP [ 8 , 19 , 20 ], in addition to being expensive.…”

Evaluation of the analytical performance of the PC100 platelet counter

“…Blood was collected on K 2 -EDTA (Vacuette®, Greiner Bio, Kremsmünster, Austria) for platelet count determination in whole blood. All measurements were performed within 3 h after blood collection to ensure platelet count stability [13].…”

“…All samples were independently quality controlled, and all measurements were performed within 3 h after blood collection to reduce the risk of preanalytical variation due to different time-intervals that may cause changes in platelet count [13,19]. The platelet count obtained in the whole blood samples or in PRP was excluded upon the occurrence of any of the following criteria: i) either one of the reference methods or the PC100 platelet counter failed to obtain a value; ii) an assignable cause occurred; iii) the results were outside of the measuring interval.…”