Both DNA and RNA are damaged by oxidation during aging and in a variety of disease states including cancer. The repair processes that are initiated to correct this damage release multiple oxidized guanine species into the urine. Cayman Chemical has developed this immunoassay for the measurement of DNA/RNA oxidative damage that detects all three oxidized guanine species; 8-hydroxy-2'-deoxyguanosine from DNA, 8-hydroxyguanosine from RNA, and 8-hydroxyguanine from either DNA or RNA. Some commercial vendors offer immunoassays that detect only 8-hydroxy-2'-deoxyguanosine, and not the other two molecules. The advantage of the Cayman kit is that it captures a more complete set of biologically relevant products of oxidative damage than do assays that are restricted to analysis of only 8-hydroxy-2'-deoxyguanosine. However, because Cayman's kit recognizes more than 8-hydroxy-2'-deoxyguanosine, it is not valid to compare the results from the Cayman ELISA Kit to an LC/MS analysis of 8-hydroxy-2'-deoxyguanosine. The ELISA value will always be significantly higher than LC/MS because the ELISA also detects 8-hydroxyguanosine and 8-hydroxyguanine.