Maternal serum trimethylamine-N-oxide is significantly increased in cases with established preeclampsia

Purpose: To compare the levels of trimethylamine-N-oxide (TMAO) in sera of normal and preeclamptic pregnancies and to explore whether serum TMAO level was associated with the severity of preeclampsia. Materials and methods: Eighty-six pregnant women in the third trimester were enrolled in this case control study. Levels of TMAO were quantified by a novel liquid chromatography/tandem mass spectrometry-based method in fasting serum samples from 43 preeclamptic women and 43 normotensive controls. Clinical characteristics, serum biomarkers of inflammation (IL-1 beta) and biomarkers of endothelial dysfunction (sVCAM-1, sFlt-1) were assessed. Results: TMAO levels were significantly higher in women with preeclampsia than those with normal pregnancy. The serum levels of TMAO were positively correlated with systolic blood pressure (r = 0.602, P < 0.001), urinary protein levels (r = 0.557, P < 0.001) and the serum levels of IL-1 beta (r = 0.633, P < 0.001), sVCAM-1 (r = 0.719, P < 0.001) as well as sFlt-1 (r = 0.763, P < 0.001) in patients with PE. Conclusions: Elevated TMAO levels are associated with higher risk of preeclampsia and correlate with increased systemic inflammation and endothelial dysfunction. Further validation of these findings with more robust multicenter prospective and longitudinal characterization of maternal serum TMAO in pregnancy may be carried out in subsequent investigations to determine its suitability as a predictive biomarker for preeclampsia.