Measurement of trimethylamine-N-oxide by stable isotope dilution liquid chromatography tandem mass spectrometry

• Published in: Analytical biochemistry Vol. 455; pp. 35 - 40
• Main Authors: Wang, Zeneng, Levison, Bruce S., Hazen, Jennie E., Donahue, Lillian, Li, Xin-Min, Hazen, Stanley L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.2014
• Subjects: Adult; Aged; blood; Cardiovascular disease; Chromatography, Liquid - methods; death; Deuterium; environmental factors; Fasting; Female; freeze-thaw cycles; Humans; Indicator Dilution Techniques; isotope dilution technique; Limit of Detection; liquid chromatography; Male; Mass spectrometry; Methylamines - blood; Middle Aged; myocardial infarction; Reference Values; Reproducibility of Results; risk factors; Spectrometry, Mass, Electrospray Ionization - methods; stable isotopes; storage temperature; stroke; tandem mass spectrometry; Tandem Mass Spectrometry - methods; Trimethylamine-N-oxide; Cardiovascular disease; Mass spectrometry; Trimethylamine-N-oxide
• ISSN: 0003-2697; 1096-0309; 1096-0309
• DOI: 10.1016/j.ab.2014.03.016

Trimethylamine-N-oxide (TMAO) levels in blood predict future risk for major adverse cardiac events including myocardial infarction, stroke, and death. Thus, the rapid determination of circulating TMAO concentration is of clinical interest. Here we report a method to measure TMAO in biological matrices by stable isotope dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) with lower and upper limits of quantification of 0.05 and >200μM, respectively. Spike and recovery studies demonstrate an accuracy at low (0.5μM), mid (5μM), and high (100μM) levels of 98.2, 97.3, and 101.6%, respectively. Additional assay performance metrics include intraday and interday coefficients of variance of <6.4 and <9.9%, respectively, across the range of TMAO levels. Stability studies reveal that TMAO in plasma is stable both during storage at −80°C for 5years and to multiple freeze thaw cycles. Fasting plasma normal range studies among apparently healthy subjects (n=349) show a range of 0.73–126μM, median (interquartile range) levels of 3.45 (2.25–5.79)μM, and increasing values with age. The LC/MS/MS-based assay reported should be of value for further studies evaluating TMAO as a risk marker and for examining the effect of dietary, pharmacologic, and environmental factors on TMAO levels.