Measuring oxidative stress involves assessing biomarkers of oxidative damage and antioxidant levels in the body. Tests may include measuring levels of malondialdehyde (MDA), 8-oxo-deoxyguanosine (8-oxo-dG), and antioxidant enzymes like superoxide dismutase (SOD). However, these tests are not routinely used in clinical practice due to variability and complexity.