Variables that affect platelet function analyzer-100 (PFA-100) closure times and establishment of reference intervals...

The PFA-100 is an in vitro system for measurement of platelet function in whole blood. To establish reference intervals in the Korean population, we investigated the relationships between PFA-100 closure times and gender, ABO blood group, citrate concentration, and time of blood collection in 120 well-characterized healthy Korean adults. Gender did not affect closure time values. Blood group O was associated with longer collagen/epinephrine (CEPI) and collagen/ADP (CADP) closure times than non-O groups (p <0.0001 for both). Closure times were shorter in samples obtained in the morning vs the afternoon. Regression analysis showed an association between CEPI and CADP closure times (p <0.0001), but there were no associations between PFA-100 results and WBC count, hemoglobin, hematocrit, platelet count, and platelet-associated parameters. The reference intervals for CEPI and CADP closure times of 3.2% citrated blood were 80-162 and 64-121 sec, respectively. The reference intervals for PFA-100 closure times in healthy Korean adults were similar to those in Western populations. Flow obstruction was observed in 31 of 480 (6.5%) measurements, but routine performance of duplicate measurements was otherwise unnecessary because of acceptable CV values. PFA-100 closure time should be interpreted with consideration of the patient's clinical presentation and factors such as ABO blood group and diurnal variation.