It is currently unclear for the necessary of pre‐heating urine samples for the accurate determination of 8‐oxo‐7,8‐dihydroguanosine (8‐oxoG) and 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxodG). Thus, we conducted this study to evaluate the effect of pre‐heat (i.e., to 37°C) on the accurate measurement of 8‐oxoG and 8‐oxodG in frozen urine samples.
Random urine samples from six healthy volunteers, six patients with renal dysfunction, and six patients with systematic diseases such as diabetes were collected, split, and stored at −80°C for up to 1 month. The frozen samples were thawed at room temperature (RT) or 37°C for different time, 10‐fold diluted with ddH2O containing 1% formic acid, and determined by self‐established LC–MS/MS method coupled with an ACQUITY™ Primer HSS T3 column.
For both apparently healthy volunteers and patients with kidney dysfunction or other systematic diseases, no significant difference between thawing the frozen urine samples at RT and 37°C was found for the accurate determinations of urinary 8‐oxoG and 8‐oxodG with this pre‐treatment and determination method.