title: Mass spectrometric quantification of salivary metanephrines-A study in healthy subjects.
abstract: BACKGROUND
  Determination of metanephrine (MN), normetanephrine (NMN), and 3-methoxytyramine (3-MT) in saliva may offer potential diagnostic advantages in diagnosing pheochromocytoma.
  
  
  METHODS
  In this preliminary study, we determined metanephrine concentrations in saliva of healthy subjects and the relationship with simultaneously measured plasma metanephrines. We also studied the possible influence of pre-analytical conditions such as a collection device, awakening, posture, and eating on the salivary metanephrine levels.
  
  
  RESULTS
  Eleven healthy subjects were included. Fasting blood and saliva samples were collected in seated position and after 30min of horizontal rest. Plasma and salivary MN, NMN, and 3-MT concentrations were determined using a high-performance liquid chromatography tandem mass spectrometric technique (LC-MS/MS) with automated solid phase extraction sample preparation. Metanephrines were detectable in saliva from all participants both in seated and supine position. No significant correlations were observed between the MN, NMN, and 3-MT concentrations in saliva and plasma in seated or supine position. Furthermore, there was no difference between MN, NMN, and 3-MT samples collected with or without a collection device.
  
  
  CONCLUSIONS
  Metanephrines can be detected in saliva with LC-MS/MS with sufficient sensitivity and precision. Our findings warrant evaluation of salivary metanephrine measurement as a novel laboratory tool in the work-up of patients suspected of having a pheochromocytoma.
authors.affiliation: Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: t.osinga@umcg.nl.
authors.forename: Thamara E
authors.initials: TE
authors.lastname: Osinga
authors.affiliation: Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: a.n.a.van.der.horst@umcg.nl.
authors.forename: Anouk N A
authors.initials: AN
authors.lastname: van der Horst-Schrivers
authors.affiliation: Department of Laboratory Medicine (EA61), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: h.j.r.van.faassen@umcg.nl.
authors.forename: Martijn
authors.initials: M
authors.lastname: van Faassen
authors.affiliation: Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: m.n.kerstens@umcg.nl.
authors.forename: Michiel N
authors.initials: MN
authors.lastname: Kerstens
authors.affiliation: Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: r.p.f.dullaart@umcg.nl.
authors.forename: Robin P F
authors.initials: RP
authors.lastname: Dullaart
authors.affiliation: Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 1-3140, 10 Center Drive, Bethesda, MD 20892, USA. Electronic address: karel@mail.nih.gov.
authors.forename: Karel
authors.initials: K
authors.lastname: Pacak
authors.affiliation: Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: t.p.links@umcg.nl.
authors.forename: Thera P
authors.initials: TP
authors.lastname: Links
authors.affiliation: Department of Laboratory Medicine (EA61), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: i.p.kema@umcg.nl.
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008676:Metanephrine / Q000097:blood / Q000378:metabolism*; D008875:Middle Aged; D012016:Reference Values; D012463:Saliva / Q000378:metabolism*; D055815:Young Adult
chemical_list: D008676:Metanephrine
keywords: LC–MS/MS; Metanephrines; Paraganglioma; Saliva