Plasma reactive oxygen species levels are correlated with severity of age-related hearing impairment in humans.

To investigate the relationship between plasma reactive oxygen species (ROS) levels and severity of age-related hearing impairment in humans. We recruited 302 adult subjects aged 40-77 years with normal or symmetrical sensorineural hearing loss. The association of plasma ROS levels on pure tone average of low frequencies (PTA-low) and pure tone average of high frequencies (PTA-high) were analyzed. Luminol-dependent chemiluminescence signals, which reflect hydrogen peroxide (H(2)O(2)), hypochlorite (HOCl/OCl(-)) and hydroxyl radicals (•OH) levels, showed significant positive association with PTA-low and PTA-high after adjusting for age, gender, central obesity, systemic diseases, and health-related habits (smoking, drinking, antioxidant intake). Lucigenin-dependent chemiluminescence signals, which mainly reflect superoxide anion (O(2)•(-)) levels, showed significant positive association with PTA-low, but not with PTA-high after adjusting for other variables. We concluded that plasma ROS levels were associated with severity of age-related hearing impairment in humans. Various ROS may differently affect auditory dysfunctions.