HPX and preeclampsia: Since hemoglobin-induced oxidative stress is a pathogenic factor in preeclampsia, the radical scavenger and heme-binder α1-microglobulin (A1M) was significantly increased in plasma of women with PE4, while the human endogenous Hb-, and heme-scavenging systems such as haptoglobin (Hp) and hemopexin (Hpx) were significantly reduced.