OS089. Elevated levels of the heme scavenger alpha-1-microglobulin in maternal plasma at the end of first trimester in patients who subsequently develop preeclampsia

Abstract

Resent research has revealed an increased concentration of free fetal hemoglobin (HbF) in maternal serum from patients who subsequently develops preeclampsia (PE). In a previous study of 96 patients we have shown that HbF in combination with the heme-scavenger alpha-1-microglobulin (A1M) are potential predictive biomarkers of PE. In this validating case-control study we aimed to confirm the previous findings, that A1M is elevated in the maternal circulation at the end of first trimester in patients who subsequently develops PE. In this study A1M was measured in plasma instead of serum. Patients were recruited from an ongoing prospective study of new biomarkers to predict and diagnose PE. In total we included 84 patients. 8 patients subsequently developed PE, 4 developed pregnancy induced hypertension (PIH) and 72 were controls with uncomplicated pregnancies. The plasma samples were all taken at 7+0-18+0 weeks of gestation (mean 12+1) and analyzed for concentrations of A1M with Radioimmuno Assay (RIA). This method has been previously described in details. Statistics was performed using one-way ANOVA. The mean plasma concentration of A1M in the PE group was 8.6mg/ml, 6.0 in the PIH group and 7.1mg/ml in the controls group. The PE group differed significantly from the controls group (p=0.004), whereas the PIH group did not differ significantly from the controls. Our findings in plasma confirm previous findings described for serum, i.e. A1M is significantly increased in in first trimester maternal plasma in patients who subsequently develops PE. Since A1M is the most efficient heme scavenger we suggest that A1M may be a physiological defense mechanism against the elevated levels of free HbF found in patients who subsequently develops PE or in patients with manifest PE. Furthermore, A1M did not increase in patients who develops PIH later in their pregnancies indicating its specificity for PE.