sFlt1 levels increase before and during the advent of signs and symptoms of preeclampsia. sFlt1 is a splice variant of vascular endothelial growth factor receptor 1 (VEGF-R1) and is capable of acting as a molecular sink to decrease active VEGF and placental growth factor (PIGF). Animal models suggest that sFlt1 plays a pivotal role in the pathogenesis of preeclampsia. Studies using apheresis to lower sFlt1 levels in patients are currently underway.