Detection and Measurement of Urinary 2-Hydroxyestradiol 17-Sulfate, a Potential Placental Antioxidant during Pregnancy

Abstract

Abstract Background: Preeclampsia is associated with a quantitative imbalance between lipid peroxide and an antioxidant coproduced in the placenta. To investigate our hypothesis that 2-hydroxyestradiol 17-sulfate (2-OH-ES) is the placental antioxidant during pregnancy, we developed an assay for 2-OH-ES in urine and studied samples from women with and without preeclampsia. Methods: The detection and measurement of 2-OH-ES in the urine of pregnant women were performed by RIA using highly specific antiserum to 2-OH-ES. To confirm the reliability of the RIA method, the same samples were analyzed by HPLC using an electrochemical detector. Results: Urinary 2-OH-ES values obtained by RIA showed a close relationship to those obtained by HPLC (y = 1.1x − 0.01; r = 0.96). The urinary 2-OH-ES concentrations during the first, second, and third trimesters were 2.0 ± 0.6 (mean ± SE, n = 13), 5.3 ± 1.3 (n = 21), and 15.3 ± 2.0 μg/mg creatinine (n = 54), respectively, and <0.15 μg/mg creatinine (n = 10) at 2–24 h after delivery. The concentrations in preeclamptic women during the third trimester were significantly lower, 3.9 ± 1.9 μg/mg creatinine (mean ± SE, n = 12). Conclusions: RIA can be used to measure urinary 2-OH-ES during pregnancy. The increase in urinary 2-OH-ES during gestation, its decrease after delivery, and the lower values in preeclampsia are consistent with a role of 2-OH-ES as a placental antioxidant.