Table 4: FXI results for the international reference preparations.

Standard

Attribute

[1]

[2]

[3]

[4]

[5]

[6]

Mean

RSD
(%)

ISTH/
SSC#4

U/mL

0.88

0.87

0.90

0.89

0.86

0.88

0.88

1.6

%label

98.9

97.8

101.1

100.0

96.6

98.9

98.9

WHO
11/236

IU/mL

0.29

0.30

0.29

0.30

0.31

0.30

0.30

2.5

%label

2.9

3.0

2.9

3.0

3.1

3.0

3.0

Remarks: The attribute "%label" expressed the FXI concentration found as a percent of the preparations' labeled potency, i.e., 0.89 U FXI/mL and 10 IU FXI/ml for the ISTH/SSC#4 and WHO 11/236 standard, respectively. While the ISTH/SSC#4 preparation was measured in six independent tests carried out by three operators, the WHO 11/236 standard was measured in six independent dilution series run on one plate.