title: A simple liquid chromatography-tandem mass spectrometry method for measuring metanephrine and normetanephrine in urine.
abstract: BACKGROUND
  Measuring urinary fractionated metanephrines is one of the initial tests in the diagnosis of pheochromocytoma. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) represents the most specific and accurate technology for this purpose. The goal of this work was to develop a simple LC-MS/MS method for measuring metanephrines in urine.
  
  
  METHODS
  Each urine sample was complexed with diphenylboronic acid, and purified on a Bond-Elute Plexa cartridge. The extract was concentrated and analyzed on a short Atlantis T3 column in 8.5 min. Metanephrines and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring.
  
  
  RESULTS
  Ion suppression was observed, but was compensated for by the respective internal standard. The analytical measurement range was 0.2-27.4 μmol/L and 0.3-14.6 μmol/L for metanephrine and normetanephrine, respectively. The intra-assay and total coefficient of variation throughout the linear ranges was 2.03%-2.11% and 2.20%-3.80% for metanephrine, and 4.50%-8.09% and 9.00%-10.00% for normetanephrine, respectively. Comparison with a commercial HPLC method using patient samples (n=65) by Passing-Bablok regression showed a slope of 1.000 and 1.014, y-intercept of -0.080 and -0.067, a correlation coefficient of 0.8830 and 0.9022, and a mean difference of 14.0% and -0.43% for metanephrine and normetanephrine, respectively.
  
  
  CONCLUSIONS
  This simple method for urine metanephrines is suitable for clinical use.
authors.affiliation: Department of Clinical Pathology, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Gabler
authors.forename: Abby
authors.initials: A
authors.lastname: Miller
authors.forename: Sihe
authors.initials: S
authors.lastname: Wang
mesh_terms: D001897:Boronic Acids / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D008676:Metanephrine / Q000737:chemistry / Q000302:isolation & purification / Q000652:urine*; D009647:Normetanephrine / Q000737:chemistry / Q000302:isolation & purification / Q000652:urine*; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D001897:Boronic Acids; D009647:Normetanephrine; D008676:Metanephrine