Demographic and laboratory determinants of 8-hydroxy-2′- deoxyguanosine (8-ohdg) urinary concentration: preliminary results from gene environment interactions in respiratory diseases (GEIRD) study

Background. The 8-hydroxy-2’-deoxyguanosine (8-OHdG) is a biomarker of oxidative stress which seems to be involved in the pathogenesis of many respiratory diseases. aims. To identify demographic and laboratory determinants of the urinary concentration of 8-OHdG. Methods. Spot-urine samples of 166 adult non-smokers (20-64 yrs) without respiratory diseases and comorbidities, were collected between 2008 and 2012 in Verona, in the frame of the GEIRD study 1 , and stored at -80°C. 8-OHdG was measured by ELISA assay. Creatinine-normalized urinary 8-OHdG concentration was analyzed by a linear regression considering age, gender, kit lot number and storage duration of urine samples as determinants. Values of the biomarker were log transformed to obtain normal distribution. results. The median of 8-OHdG/creatinine and of storage duration was 3.48 ng/mg (range:0.06-38.36) and 376 days (range: 36-762), respectively. 8-OHdG/creatinine was significantly and negatively associated with both storage duration (p<0.001) and kit lot number (p= 0.001), while it did not vary according to age and gender. When the storage duration effect was accounted for, the residual 8-OHdG concentration attributable to the kit was still statistically significant (p <0.05). Conclusions. The 8-OHdG/creatinine concentration decreases with increasing storage duration of urine samples, and varies according to the kit used. These laboratory features should be taken into account when analyzing biomarkers of oxidative stress.