This study investigated the detection of 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker of oxidative DNA damage using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in peripheral leukocyte DNA. Elevated 8-OHdG levels have been linked to various conditions, including cardiovascular diseases and metabolic disorders, making it a valuable marker for assessing oxidative stress.