The sensitivity of measuring thiobarbituric acid reactive substances (TBARS) has made this assay the method of choice for screening and monitoring lipid peroxidation, which is a major indication of oxidative stress.

Malondialdehyde (MDA) forms a 1:2 adduct with thiobarbituric acid; the adduct can be measured by fluorometry. Biological specimens contain a mixture of TBARS, including lipid hydroperoxides and aldehydes. In practice, TBARS are expressed in equivalent numbers to MDA.