Grew, Ida Sophie2; Cejvanovic, Vanja3; Broedbaek, Kasper1; Henriksen, Trine4; Petersen, Morten1; Andersen, Jon T1; Jimenez-Solem, Espen1; Weimann, Allan1; Poulsen, Henrik E1
1 KLINISK FARMAKOLOGISK AFDELING, Bispebjerg and Frederiksberg Hospital, The Capital Region of Denmark2 University of Copenhagen3 Institut for Klinisk Medicin4 Klinik for Plastikkirurgi, Brystkirurgi og Brandsårsbehandling, HovedOrtoCentret Rigshospitalet, Rigshospitalet, The Capital Region of Denmark
Aims. Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) are biomarkers of oxidative stress with clinical potential in a variety of diseases. As part of their clinical validation, this study aimed to investigate whether the urinary excretion of 8-oxodG and 8-oxoGuo undergoes diurnal variation and to evaluate the validity of 6-hour sampling as well as creatinine corrected spot urine sampling. Methods. A total of 23 healthy study subjects collecting their 24-h urine in four fractions covering 6 hours each. Urinary 8-oxodG and 8-oxoGuo levels were quantified using a modified version of UPLC-MS/MS. Results. No significant difference in excretion levels between the 12-h diurnal and 12-h nocturnal state or between the four 6-h periods during the day was found for either biomarker. A strong linear relationship between the excretion levels in each of the 6-h periods and the 24-h excretion level was shown for both biomarkers. Creatinine correction of the 6-h levels reduced the biological variation of the excretion levels and weakened the linear relationship with the uncorrected 24-h excretion level for both biomarkers. The correlations were strengthened when the 24-h excretion level was expressed per kg body weight. Conclusion. The results showed that 8-oxodG and 8-oxoGuo did not undergo diurnal variation in the study population overall and hence that the time of sampling is not crucial. Furthermore, 6-h sampling can be used as a substitute for 24-h sampling, and creatinine corrected sampling may be rational due to the reduction in biological variation of the biomarkers and the reasonable correlation with body weight-adjusted 24-h levels.
Scandinavian Journal of Clinical and Laboratory Investigation, 2014, Vol 74, Issue 4, p. 336-343