Longitudinal study of urinary 8-hydroxy-2 '-deoxyguanosine excretion in healthy adults

Numerous studies have investigated the urinary excretion of 8-hydroxy-2'-de oxyguanosine (8-OHdG) as a biomarker for the assessment of oxidative DNA da mage in humans. In this study, we performed six consecutive series of measu rement of urinary levels of 8-OHdG in 68 healthy probands, in order to prov ide information on the intra- and inter-individual variability of 8-OHdG an d to estimate the influence of smoking, age, sex, body weight and body mass index (BMI) on the excretion of 8-OHdG. The intraindividual coefficient of variation (CV) of urinary 8-OHdG/24h ranged from 0.18 to 1.06 (mean CV = 0 .48). Women excreted significantly lower amounts of 8-OHdG/24h than men, bu t the difference lost its significance when the body weight or urinary crea tinine were used as covariates. By multiple linear regression analysis sign ificant correlations between the mean individual levels of 8-OHdG/24h excre tion and urinary creatinine (r(P)=0.61), and cotinine (r(P) = 0.27) have be en observed, whereas no statistically significant effect of age, body weigh t and BMI was found. The 8-OHdG/creatinine ratio was found to be significan tly increased in 23 smokers (1.95 +/-0.40 mu mol/mol) opposed to 45 non-smo king probands (1.62 +/-0.50 mu mol/mol), which is in good agreement with pr eviously published data. No effect of passive smoking on the excretion of 8 -OHdG was found. From our data we conclude that the intraindividual variabi lity of urinary 8-OHdG excretion has been underestimated so far, indicating that values of 8-OHdG measured by single spot monitoring are not represent ative for individual base levels.