title: Urinary 8-hydroxydeoxyguanosine is elevated in patients with nephrolithiasis.
abstract: 8-hydroxydeoxyguanosine (8-OHdG) is an oxidatively modified guanosine, which has been widely used as an oxidative DNA damage marker in various diseases. The present study aimed to determine urinary 8-OHdG in nephrolithiasis patients and evaluate its clinical significance. Thirty-six nephrolithiasis patients and 30 healthy subjects were recruited. Urine volume, creatinine, malondialdehyde, beta-N-acetylglucosaminidase (NAG) activity and proteins were measured in 24 h urine samples. Urinary 8-OHdG was determined by competitive enzyme-linked immunosorbent assay. Mineral composition of stones was analyzed using Fourier-transformed infrared spectroscopy. Nephrolithiasis patients excreted urinary 8-OHdG significantly higher than healthy controls. Urinary 8-OHdG levels compared among patients with calcium oxalate, struvite and uric acid stones were insignificantly different. The urinary NAG activity correlated positively with urinary 8-OHdG. Multiple linear regression showed that urinary NAG activity was an independent predictor of urinary 8-OHdG level. Receiver operating characteristic analysis revealed that the urinary 8-OHdG test was adequate for diagnosing nephrolithiasis. At 10 mug/g creatinine cutoff, the 8-OHdG test imparted high specificity (96.67%) and a positive predictive value (91.67%). In conclusion, this is the first report of elevated urinary 8-OHdG excretion in nephrolithiasis patients indicating increased oxidative DNA damage. Increased renal tubular damage was independently associated with elevated urinary 8-OHdG. Elevated urinary 8-OHdG levels adjunct with metabolic profile may be useful for identifying people at risk of stone development.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Bangkok 10330, Thailand.
authors.forename: Chanchai
authors.initials: C
authors.lastname: Boonla
authors.forename: Rattiporn
authors.initials: R
authors.lastname: Wunsuwan
authors.forename: Kriang
authors.initials: K
authors.lastname: Tungsanga
authors.forename: Piyaratana
authors.initials: P
authors.lastname: Tosukhowong
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D004249:DNA Damage / Q000502:physiology*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000503:physiopathology / Q000652:urine*; D018384:Oxidative Stress / Q000502:physiology*
chemical_list: D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine