Soluble fms-like tyrosine kinase-1

Soluble fms-like tyrosine kinase-1 (sFlt-1 or sVEGFR-1) is a tyrosine kinase protein that disables proteins that cause blood vessel growth.Soluble Flt-1 (sFlt-1) is a splice variant of VEGF receptor 1 (Flt-1) which is produced by a variety of tissues.¹ These proteins act as a receptor of vascular endothelial growth factor (VEGF), a potent angiogenic growth factor. (Another VEGF receptor is KDR).

sFlt-1 (soluble fms-like tyrosine kinase-1 – also known as VEGF receptor-1) binds and reduces free circulating levels of the proangiogenic factors VEGF (vascular endothelial growth factor) and PlGF (placental growth factor). sFlt-1 thereby blunts the beneficial effects of these proangiogenic factors on maternal endothelium, with consequent maternal hypertension and proteinuria. Serum levels of PlGF and sFlt-1 are altered in women with preeclampsia. Moreover, circulating levels of PlGF and sFlt-1 can discriminate between a normal pregnancy and that with preeclampsia even prior to clinical presentation, and sFlt-1 and PlGF are associated with disease severity and the onset of symptoms.²

In normal pregnancy, the pro-angiogenic factor PlGF increases during the first two trimesters and decreases as pregnancy progresses to term. In contrast, levels of the anti-angiogenic factor sFlt-1 remain stable during the early and middle stages of gestation and increase steadily until term. In women who develop preeclampsia, sFlt-1 levels have been...
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