title: Hydrogen peroxide in urine as a potential biomarker of whole body oxidative stress.
abstract: The level of hydrogen peroxide (H2O2) in urine has been suggested as a potential biomarker of whole body oxidative stress, but issues of stability, reproducibility and biological variation have not been investigated to date. In this study, we used a refined protocol, which demonstrated improved sensitivity and precision, to determine the stability of H2O2 in urine, and to measure its concentration in apparently healthy subjects. We also investigated intra-individual variation within and between days. Results showed that H2O2 in urine is stable for up to 48 h at 4 degrees C, however, storage of urine at room temperature was associated with up to 50% increase in H2O2 concentration over a few hours. Total H2O2 in freshly voided urine from 55 healthy, fasting subjects ranged from 0.84 to 5.71 microM, or 90-1164 micromol H2O2/mol creatinine. Intra-individual variation was wide. Even when concentration corrected and collected at the same time of day, 2- to 3-fold variation was seen over 4 consecutive days, and over the course of a single day the creatinine-corrected H2O2 also varied significantly. We suggest that this large biological variation limits the usefulness of urine H2O2 as a biomarker of oxidative stress, the exception being when the effects of disease, therapy or diet induce very large changes in its concentration.
authors.affiliation: Ageing and Health Section, School of Nursing, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, People's Republic of China.
authors.forename: J W M
authors.initials: JW
authors.lastname: Yuen
authors.forename: I F F
authors.initials: IF
authors.lastname: Benzie
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000652:urine*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress
chemical_list: D015415:Biomarkers; D006861:Hydrogen Peroxide