There are several markers that can be indirect indicators of oxidative stress count that have been mentioned, for example measuring the outputs of the oxidative stress process, some of which include:
Measurement of Malondialdehyde, 4-Hydroxynonenal, 3-nitrotyrosine, Methemoglobin, Hydroxyguanosine, Methionine sulphoxide and others
There are many biomarkers of oxidative stress, e.g. content of ROS using DCFH-DA, H2O2, and enzymes activity of GST (glutathione-S-transferases), SOD, GPx, CAT.