8-OHdG (8-hydroxy-2-deoxyguanosine)

Marker of oxidative damage to DNA building blocks – it shows how much oxidised guanosine is removed and excreted by the body. Is looked at in the diagnostics of oxidative stress and cellular ageing.

What 8-OHdG shows

Reactive oxygen compounds, above all the hydroxyl radical, also attack the genetic material. The DNA building block guanine is the most easily oxidised; this produces 8-oxoguanine, as a nucleoside 8-hydroxy-2'-deoxyguanosine (8-OHdG). The cell recognises this damage: repair enzymes such as OGG1 cut the altered base out of the DNA, and the enzyme MTH1 removes oxidised building blocks from the pool before they are incorporated at all. The breakdown products, including 8-OHdG, enter the blood and are excreted unchanged in urine. The amount in urine therefore reflects how much oxidative DNA damage arises and is removed throughout the body; the DNA of the mitochondria, which lies close to the respiratory chain, also contributes.

Low 8-OHdG – what does it mean?

A low value shows that few DNA building blocks are being oxidised: the antioxidant protective systems – superoxide dismutase, catalase, glutathione and the selenium-containing glutathione peroxidases – neutralise reactive oxygen compounds before they reach the genetic material. Because the value also depends on repair activity, it is considered together with other markers of oxidative stress.

High 8-OHdG – what happens in the body?

A high value shows that more DNA building blocks are being oxidised and repaired. If 8-oxoguanine remains in the DNA until the next cell division, it can pair with the wrong partner during copying, so that permanent changes in the genetic material arise. The DNA of the mitochondria is particularly sensitive: damage to it impairs the respiratory chain, which can then release even more reactive oxygen compounds. More oxidative DNA damage arises with chronic inflammation, smoking, air pollutants, UV and ionising radiation, persistently high blood sugar and low antioxidant reserves; studies have observed raised values in diabetes and cardiovascular disease, among others.

The interpretation is given in your report.