Introduction Gestational measures of placental growth factor (PlGF) and soluble fms-like tyrosine kinase (sFlt-1) may predict later pre-eclampsia and differentiate pre-eclampsia from gestational hypertension. To validate the clinical utility of rapid measures of these circulating factors using an automated immunoturbidimetric assay the authors compared levels measured with an ELISA kit.

Methods 159 women were followed from 10 weeks until 3-month postpartum. Pre-eclampsia developed in 23 women, gestational hypertension developed in 10, and the remaining 128 subjects remained normotensive. Serum PlGF and sFlt-1 were measured in duplicate using a manual ELISA kit (RnD Systems) and an automated assay (Roche Diagnostics) to assess interassay agreement.

Results Between 10 and 17 weeks, both assays demonstrated a higher ratio of serum sFlt-1 to PlGF (ELISA, p<0.001; Roche, p=0.002) in women who later developed preterm pre-eclampsia (<37-week gestation) compared with those who did not. These differences persisted throughout pregnancy and distinguished women with pre-eclampsia from those with gestational hypertension. There was good agreement between levels of PlGF and sFlt-1 obtained from the two assays (Bland–Altman regression analysis).

Conclusion In a prospective study, the authors have demonstrated that from early pregnancy there is a higher ratio of sFlt-1:PlGF in women who later develop preterm pre-eclampsia. Measures obtained from manual and rapid automated assays were comparable. Automated assessment of PlGF and sFlt-1 in early pregnancy hold promise as a tool for predicting future pre-eclampsia and in the presence of new onset gestational hypertension, in differentiating pre-eclampsia from gestational hypertension. Larger studies are required to confirm these observations.