Measurement of trimethylamine-N-oxide by stable isotope dilution liquid chromatography tandem mass spectrometry.
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.
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA. Electronic address: wangz2@ccf.org.
Zeneng
Z
Wang
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Bruce S
BS
Levison
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Jennie E
JE
Hazen
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Lillian
L
Donahue
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Xin-Min
XM
Li
Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Stanley L
SL
Hazen
D000328:Adult; D000368:Aged; D002853:Chromatography, Liquid / Q000379:methods*; D003903:Deuterium; D005215:Fasting; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D057230:Limit of Detection; D008297:Male; D008744:Methylamines / Q000097:blood*; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
D008744:Methylamines; D003903:Deuterium; C005855:trimethyloxamine
Cardiovascular disease; Mass spectrometry; Trimethylamine-N-oxide