Objective: Zinc is a structural component of superoxide dismutase (Cu/Zn-SOD) that has a vital antioxidant role. It is among the first line of defense in detoxification of products resulting from oxidative stress. It has been recently observed that reactive oxygen species (ROS), which is the product of the oxidative stress, are implicated in the pathology of the inner ear and the peripheral and central auditory pathways. Hence, this work was designed to find out the prevalence of hypozincemia in patients with tinnitus. Also to assess the correlation between zinc levels to superoxide dismutase activity in blood and to tinnitus loudness in one hand and to investigate the effect of Zn supplementation on the severity of tinnitus on the other hand.
Study Design: Randomized, prospective, placebo-controlled study.
Materials and Methods: This study included 168 patients suffering from bilateral tinnitus of variable duration. Only, 39 (23.2%) of patients had a low serum level of zinc (less than 70 μg /dl). This group of hypozincemia was classified into study and control groups. All subjects in this study were submitted to hearing evaluation, detailed history of tinnitus and tinnitus questionnaire using the developed Arabic version of tinnitus handicap inventory (THI). Zinc levels in serum and plasma levels of superoxide dismutase (SOD) were determined for all patients one day before zinc supplementation, 3 months and 6 months after treatment.
Results: 23.2% of patients with tinnitus had low serum level of zinc. No significant improvement of hearing sensitivity occurred in both study groups; placebo and zinc group. After zinc treatment, 60% of patients with hypozincemia in the study group improved not only in serum zinc level but also in plasma level of SOD significantly within 3 months after treatment by zinc. The improvement of subjective tinnitus despite of being significant statistically, it didn’t reach to complete cure from tinnitus in any patient.
Conclusions: 60% of patients with hypozincemia were improved after zinc supplementation not only in serum zinc level and SOD but also in subjective symptoms of tinnitus.