DECREASED TRANSFERRIN AND INCREASED TRANSFERRIN SATURATION IN SERA OFWOMEN WITH PREECLAMPSIA - IMPLICATIONS FOR OXIDATIVE STRESS

OBJECTIVE: The concerted iron-binding antioxidant activity of transfer rin and ceruloplasmin decreases with increasing transferrin saturation by iron. We examined interactions between serum iron and iron-binding capacity and concentrations of the lipid peroxidation metabolite malo ndialdehyde in normal and preeclamptic pregnancies. We also asked if t he release of iron from free hemoglobin by lipid hydroperoxides is a p otential mechanism to increase transferrin saturation in preeclampsia. STUDY DESIGN: Predelivery and 24 to 48 hour postpartum venous blood w as collected from 19 women with uncomplicated pregnancies and 17 with preeclampsia. Serum iron, Iron binding capacity, and malondialdehyde w ere measured. In a subset of predelivery samples electron paramagnetic resonance spectroscopy was used to determine diferric transferrin, to tal transferrin, and ceruloplasmin concentrations and to examine inter actions of an organic hydroperoxide with hemoglobin and transferrin. R ESULTS: Antepartum serum iron concentrations were 46% greater, percent saturation of iron binding capacity was 98% greater, and malondialdeh yde 50% greater, whereas total iron-binding capacity was 14% lower, in women with preeclampsia. By 48 hours post partum group differences be tween these variables other than total iron-binding capacity were not observed. Electron paramagnetic resonance spectroscopy confirmed antep artum differences and that total iron-binding capacity and percent sat uration were equivalent to total transferrin and the ratio diferric tr ansferrin/total transferrin, respectively. Antepartum concentrations o f ceruloplasmin were not different. Antepartum malondialdehyde concent rations correlated positively with percent transferrin saturation and negatively with unsaturated iron-binding capacity (apotransferrin). El ectron paramagnetic resonance spectroscopy demonstrated that the relea se of iron from free hemoglobin by lipid hydroperoxides in serum is a potential mechanism to increase transferrin saturation. CONCLUSION: In creased transferrin saturation and decreased unsaturated iron-binding capacity in preeclampsia may occur consequent to oxidative stress and then further promote oxidative stress by decreasing serum antioxidant buffering against redox-active iron.