Summary. The PFA-100Ò (PFA) diagnostic system for the detection of platelet dysfunction was evaluated to determine reference ranges in a normal population. The PFA determines the primary haemostasis capacity (PHC) of anticoagulated whole blood, expressed by the system's closure time (CT). In this study the CT reference ranges were determined for blood samples collected in 105 mmol/l (3´2%) buffered citrate and the effect of gender, smoking, and use of oral contraceptives on reference ranges was assessed. Each of the 309 healthy blood donors from ®ve blood centres was con®rmed to have normal platelet function before inclusion in the study. Blood samples were tested in duplicate with both the collagen/epinephrine (Col/Epi) and collagen/ADP (Col/ADP) test cartridges.PFA reference ranges (90% central intervals of measured closure times) for both cartridge types were similar for all groups. Subgroup analysis showed that neither gender nor oral contraceptive usage had any effect on PHC. The 95% cut-off value for the Col/Epi CT was slightly higher for smokers than for non-smokers, an effect more pronounced in female than in male donors. However, the small difference did not justify establishment of speci®c reference ranges for smokers. Data from all included subjects were pooled to calculate the CT reference ranges for blood samples collected in 105 mmol/l buffered citrate (Col/Epi 82±150 s; Col/ADP 62±100 s). Normal levels of ®brinogen, as well as normal platelet counts and normal haematocrit levels, appeared not to in¯uence the PHC. Because slight but signi®cant differences of the reference ranges were observed between some of the participating sites, in-house con®rmation of these reference range guidelines is recommended.

Significant ABO-group-specific differences in nonvascular primary hemostasis could be found by IVBT. The differences are small, however, and lie within the normal range. Whether these differences have any biologic relevance can only be speculated.

The COM.TEC machine makes it possible to obtain WBC-reduced SDPs that comply with current standards.