44 Chapter 3 Table 1: Cut-off values for the reference ranges of haemostasis parameters. The cut-off values of PT, APTT, VWF-AG and VWF ristocetin co-factor activity were established by the Department of Clinical Chemistry and Hematology of the Gelre Hospitals in Apeldoorn. Cut-off values of platelet function and VWF function was determined in 123 healthy employees of the UMC Utrecht. Cut-off values of TG parameters were determined in 126 healthy volunteers in and around the Maastricht UM. Reference range (s) low high APTT PT 24 10 35 15 Platelet function Reference range (%) low high CRP P-selectin aIIbb3 48 63 151 137 TRAP P-selectin aIIbb3 65 35 134 164 ADP P-selectin aIIbb3 40 43 160 157 Thrombin Generation Reference range (%) low high Lagtime 1 pM TF 5 pM TF 65 73 123 125 ETP 1 pM TF 5 pM TF 73 72 143 139 Peak 1 pM TF 5 pM TF 37 71 156 123 ttPeak 1 pM TF 67 143 5 pM TF 84 126 Reference range (%) lowest value highest value VWF antigen VWF ristocetin co-factor activity Function (flow cytometry) 50 50 52 150 150 147 None of the cases nor the controls had prolonged PT, suggesting that there was no coagulation factor deficiency in the extrinsic pathway (Figure 1B). Quantitative platelet function was normalized against the 26 healthy control subjects, whose blood was collected in an identical setting and at the same hour as the patients’ blood collection, to guarantee that the normalization was not biased by any pre-analytical bias. The platelet activation was measured with three different agonists: TRAP (SFLLRN) to trigger the PAR-1 receptor (Figure 2A), CRP to trigger the GPVI receptor (Figure 2B) and ADP to trigger the P2Y12 receptor (Figure 2C).
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