Oxidized and free whole blood thiols in preeclampsia

Objective: To measure levels of oxidized and free thiols in whole blood of normotensive pregnant and preeclamptic women and evaluate the role of oxidative stress. Methods: We measured whole blood oxidized and free levels of cysteine, homocysteine, cysteinylglycine, and glutathione by high performance liquid chromatography in women with normotensive pregnancies (n = 50), preeclampsia (n = 29), and preeclampsia complicated by the hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome (n = 16). Results: Oxidized and free levels (median [range], mu mol/L) of cysteine and homocysteine were higher in women with preeclampsia than normotensive pregnancies (45 [27-81] versus 29 [9-91], P <.001, and 98 [57-193] versus 69 [33-215], P <.001; 0.8 [0.2-4.4] versus 0.4 [0.01-1.6], P <.001, and 2.1 [0.7-9.4] versus 1.2 [0.2-21.2], P<.01; respectively). The Patios of free to oxidized cysteine, homocysteine, and cysteinylglycine were lower in preeclampsia than normotensive pregnancy (2.2 [1.3-3.0] versus 2.4 [1.7-4.3], P <.001; 2.3 [0.5-5.4] versus 2.9 [1.1-24], P <.001; 4.1 [2.3-11.6] versus 5.4 [2.6-24.3], P <.02, respectively), indicating a shift in favor of the oxidized form of those thiols. In HELLP syndrome, levels of oxidized and free cysteine and levels of oxidized homocysteine were higher than normal (44 [33-63] versus 29 [9-91], P <.001, and 102 [82-133] versus 69 [33-215], P <.001; 1.0 [0.3-2.9] versus 0.4 [0.01-1.6], P <.001, respectively). No significant differences were found in oxidized glutathione levels in women with preeclampsia (22 [5-49] versus 17 [2-60], P =.06) or free levels in preeclamptic women with HELLP syndrome (757 [624-993] versus 842 [539-1516], P =.09) as compared with normotensive pregnant women. The ratios of free to oxidized cysteinylglycine and glutathione were higher in women with HELLP syndrome than in those with preeclampsia (5.4 [3.3-12.7] versus 4.1 [2.3-11.6], P =.02, and 56 [28-124] versus 45 [16-166], P =.02, respectively). Conclusion: Significantly lower ratios of free to oxidized cysteine, homocysteine, and cysteinylglycine in preeclampsia might indicate oxidative stress. (Obstet Gynecol 2001;97: 272-6. (C) 2001 by The American College of Obstetricians and Gynecologists.).