Analytical assay
Blood samples were centrifuged at 1,200 g for 10 min. The sFlt-1, PlGF
and NT-proBNP concentrations were determined using an
electrochemiluminescence immunoassay (Elecsys PlGF, sFlt-1 and
NT-proBNP) on the Cobas e601 automated immunoanalyser (Roche
Diagnostics, Germany) with a turnaround time of 18 min. The measuring
ranges were 3-10,000 pg/ml for PlGF, 10‑85,000 pg/ml for sFlt-1 and
5-35,000 ng/ml for NT-proBNP, with corresponding Limits of
Quantification of 10 pg/ml, 15 pg/ml and 5 ng/ml, respectively. The
inter-assay coefficients of variation, determined with PreciControl
Multimarker 1 and 2 for PlGF and sFlt-1 and with PreciControl Cardiac 1
and 2 (Roche Diagnostics, Germany) for NT-proBNP, ranged from 1.5% to
4.5% throughout the study. No specific interferences have been reported
for any of the assays used.