title: Urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a specific marker of oxidative stress, using direct, isocratic LC-MS/MS: Method evaluation and application in study of biological variation in healthy adults.
abstract: BACKGROUND
  Urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a specific biomarker of oxidative stress. We evaluated a modified LC-MS/MS assay for urine 8-oxodG and determined biological variation in healthy adults.
  
  
  METHODS
  Untreated urine was injected into an isocratic LC-MS/MS system (positive-ion MRM mode). Urine 8-oxodG in 51 healthy volunteers was measured; within- and between-day variations in 23 healthy volunteers were investigated.
  
  
  RESULTS
  Dose-response was linear to 452 nmol/l; limit of detection=2.3 nmol/l; within-run and between-run CVs were <3.0% and <4.7%, respectively; recovery=97%-101%; accuracy=97.7-103.5%. Urine 8-oxodG (median, mean [SD]): 1.70, 1.70[0.60]nmol/mmol creatinine (n=51). Men had higher (p=0.027) concentrations than women matched for age and body mass index: mean [SD]: 1.90[1.60]; n=26 vs. 1.50[0.55]; n=25. Within- and between-day variations were wide but random. No significant differences were seen overall across time-points within 1 day or at the same time-point across 5 consecutive days.
  
  
  CONCLUSIONS
  The method has advantages of speed and relative simplicity as it does not require sample pre-treatment for 8-oxodG extraction, the use of internal standard or gradient LC elution and has high linearity, specificity, precision and recovery. Biological variation in urine 8-oxodG is wide, but no within- or between-day differences at the group concentration were seen in healthy adults.
authors.affiliation: Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
authors.forename: Kam-fai
authors.initials: KF
authors.lastname: Lee
authors.forename: Wai-yuen
authors.initials: WY
authors.lastname: Chung
authors.forename: Iris F F
authors.initials: IF
authors.lastname: Benzie
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D018384:Oxidative Stress; D012016:Reference Values; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D015415:Biomarkers; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine