title: Comprehensive detection of disorders of purine and pyrimidine metabolism by HPLC with electrospray ionization tandem mass spectrometry.
abstract: BACKGROUND
  Clinical presentation and disease severity in disorders of purine and pyrimidine metabolism vary considerably. We present a method that allows comprehensive, sensitive, and specific diagnosis of the entire spectrum of abnormalities in purine and pyrimidine metabolism in 1 analytical run.
  
  
  METHODS
  We used reversed-phase HPLC electrospray ionization tandem mass spectrometry to investigate 24 metabolites of purine and pyrimidine metabolism in urine samples from healthy persons and from patients with confirmed diagnoses of inherited metabolic disorders. Urine samples were filtered and diluted to a creatinine concentration of 0.5 mmol/L. Stable-isotope-labeled internal standards were used for quantification. The metabolites were analyzed by multiple-reaction monitoring in positive and negative ionization modes.
  
  
  RESULTS
  Total time of analysis was 20 min. Recovery (n = 8) of a compound after addition of a known concentration was 85%-133%. The mean intraday variation (n = 10) was 12%. The interday variation (n = 7) was < or =17%. Age-related reference intervals were established for each compound. Analysis of patient urine samples revealed major differences in tandem mass spectrometry profiles compared with those of control samples. Twelve deficiencies were reliably detected: hypoxanthine guanine phosphoribosyl transferase, xanthine dehydrogenase, purine nucleoside phosphorylase, adenylosuccinate lyase, uridine monophosphate synthase, adenosine deaminase, adenine phosphoribosyl transferase, molybdenum cofactor, thymidine phosphorylase, dihydropyrimidine dehydrogenase, dihydropyrimidinase, and beta-ureidopropionase.
  
  
  CONCLUSIONS
  This method enables reliable detection of 13 defects in purine and pyrimidine metabolism in a single analytical run.
authors.affiliation: Division of Metabolic Diseases, Department of General Pediatrics, University Children's Hospital Heidelberg, Heidelberg, Germany. Susen.Hartmann@med.uni-heidelberg.de
authors.forename: Susen
authors.initials: S
authors.lastname: Hartmann
authors.forename: Jürgen G
authors.initials: JG
authors.lastname: Okun
authors.forename: Christiane
authors.initials: C
authors.lastname: Schmidt
authors.forename: Claus-Dieter
authors.initials: CD
authors.lastname: Langhans
authors.forename: Sven F
authors.initials: SF
authors.lastname: Garbade
authors.forename: Peter
authors.initials: P
authors.lastname: Burgard
authors.forename: Dorothea
authors.initials: D
authors.lastname: Haas
authors.forename: Jörn Oliver
authors.initials: JO
authors.lastname: Sass
authors.forename: William L
authors.initials: WL
authors.lastname: Nyhan
authors.forename: Georg F
authors.initials: GF
authors.lastname: Hoffmann
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007223:Infant; D011686:Purine-Pyrimidine Metabolism, Inborn Errors / Q000175:diagnosis* / Q000652:urine; D011687:Purines / Q000652:urine*; D011743:Pyrimidines / Q000652:urine*; D012016:Reference Values; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D011687:Purines; D011743:Pyrimidines