sFlt-1 and PlGF kinetics during and after pregnancy in women with suspected or confirmed preeclampsia

Objectives To assess the evolution of the sFlt-1/PlGF ratio in women with suspected or with confirmed preeclampsia and to investigate the changes in sFlt-1 and PlGF levels in preeclamptic women after delivery. Methods In this exploratory tertiary referral university centre study, using the Roche Diagnostics Elecsys assay, sFlt-1 and PlGF were determined in two groups of patients. In the first group of 46 patients with suspected or confirmed preeclampsia, sFlt-1 and PlGF were measured at least twice during their pregnancy. Women had singleton pregnancies and a median pregnancy duration of 26 weeks (range 18 – 40 weeks). In the second group, sFlt-1 and PlGF of 26 preeclamptic patients were determined before and after delivery. The median gestational age at inclusion was 29 weeks (16 – 37) and the median days between antepartum measurement and delivery was 2 days (1 – 7). Results In the first group, 90% of patients with a sFlt-1/PlGF ratio ≤38 at baseline (n = 30), ruling out PE, the sFlt-1/PlGF ratio remained stable for up to 100 days. In 16 patients with a sFlt-1/PlGF ratio >38 and in 10% of those with a sFlt-1/PlGF ratio <38 at baseline the ratio increased further. In the second group, after delivery, sFlt-1 dropped to <1% of its pre-delivery values with a half-life of 1.4 ± 0.3 days, while PlGF dropped to ≈ 30% of its pre-delivery values with a half-life of 3.7 ± 4.3 days. Conclusions Based on this small cohort, up to 10% of women admitted with suspected or confirmed PE presenting with a sFlt-1/PlGF ratio ≤38 display a rise of this sFlt-1/PlGF ratio in subsequent weeks, implying that repeated determination of the sFlt-1/PlGF ratio is required to reject this condition definitively. Furthermore, the rapid and pronounced decline of sFlt-1 values after delivery in patients with PE/HELLP suggests that sFlt-1, in contrast with PlGF, is almost entirely placenta-derived.