Address for correspondence

Under homeostatic conditions, an equilibrium state between amounts of free radicals formed and their scavenging is observed. Free radicals are destructive only when present in excess. Pathological changes within cells and tissues can result from a persistent excess of free radicals. Living organisms are increasingly exposed to oxidative stress, resulting in oxidative DNA modifications. One such modification is 8-hydroxy-2’-deoxyguanosine (8-OHdG). It is considered a biomarker of oxidative stress and oxidative DNA damage. It has been found both in physiological fluids and in cells. This paper presents methods found in the literature for determining 8-OHdG expression in various kinds of biological material – blood, urine or liver homogenates. Methods for determining the biomarker expression have been grouped into direct and indirect methods, and the various levels of 8-hydroxy-2’-deoxyguanosine that can be determined by the different techniques are presented. The basic pros and cons of the various techniques are also discussed.