Summary
Two candidate ECAA reference preparations have been calibrated in a multicentre exercise
at 14 representative national laboratories to provide reference thromboplastin for
a large field study in 16 European countries. Two preparations were required because
of the established differences in ISI arising from the two main routes of calibration
via rabbit and human IRP. To be comparable with working reagents in everyday use a
human plain recombinant reagent of low ISI and a rabbit plain preparation of moderately
high ISI were selected. A precise calibration of the two candidate preparations has
been achieved with the manual PT technique and an ISI of 0.95 (SE 0.0078) for the
human reagent and 1.67 (SE 0.0322) for the rabbit reagent.
