title: Assay of serum allantoin in humans by gas chromatography-mass spectrometry.
abstract: BACKGROUND
  The small amount of allantoin present in human serum results from free radical (FR) action on urate and may provide a stable marker of free radical activity in vivo. We describe a gas chromatography-mass spectrometry (GC-MS) assay for serum allantoin and report a reference range in healthy individuals.
  
  
  METHODS
  Fasting blood samples were obtained from 134 healthy middle-aged volunteers (56 men, mean age 55, range 45-72; 78 women, mean age 55, range 50-72) Allantoin was assayed using 15N(2) allantoin as an internal standard. After isolation from aqueous standards or serum by extraction onto an anion exchange column (AG-MP1), allantoin was derivatised with N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA). Derivatives were injected onto an HP-1 column and analysed using a Mass Selective Detector with Single Ion Monitoring at 398 and 400 m/z.
  
  
  RESULTS
  The distribution of serum allantoin concentrations in men and women was non-Gaussian and log transformation was used for the analysis of data. Women (10.8 +/- 1.7 micromol/l (mean +/- S.D.)) had significantly lower serum allantoin levels than men (13.4 +/- 1.6 micromol/l, p=0.015). Reference ranges (95% CI) for middle-aged healthy subjects were 7.4-46.8 micromol/l (men) and 3.7-31.2 micromol/l (women).
  
  
  CONCLUSIONS
  Gas chromatography-mass spectrometry provides a reliable and accurate method for the determination of serum allantoin.
authors.affiliation: Department of Clinical Chemistry, Imperial College School of Medicine, Charing Cross Campus, London, UK.
authors.forename: Darrell V
authors.initials: DV
authors.lastname: Pavitt
authors.forename: Sue
authors.initials: S
authors.lastname: de Fonseka
authors.forename: Nisrin
authors.initials: N
authors.lastname: Al-Khalaf
authors.forename: Janice M
authors.initials: JM
authors.lastname: Cam
authors.forename: David A
authors.initials: DA
authors.lastname: Reaveley
mesh_terms: D000368:Aged; D000481:Allantoin / Q000097:blood*; D001161:Arteriosclerosis / Q000097:blood; D015415:Biomarkers; D002138:Calibration; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D015415:Biomarkers; D005609:Free Radicals; D008055:Lipids; D000481:Allantoin