Relationship between serum ferritin level and amikacin ototoxicity.

OBJECTIVES Aminoglycosides are highly effective against bacteria but have serious side-effects including ototoxicity and nephrotoxicity. One of the theories in aminoglycosides ototoxicity is that Iron-aminoglycoside complex causes ototoxicity by creating free radicals. Based on this theory, the relationship between serum iron level and amikacin ototoxicity was studied to determine whether more iron results in more ototoxcity. METHODS This prospective cohort study was conducted from August 2005 to October 2008. Patients with amikacin prescription and different serum-ferritin levels were examined. Burned patients with amikacin prescription were divided into Group1 (89 patients; serum-ferritin >150) and Group2 (92 patients, serum-ferritin <150). Their hearing thresholds and red-blood-cells indices were compared using t- and paired t-test. RESULTS In comparing the two groups, thresholds of Group1 were higher than Group2 at all frequencies, and the difference was statistically significant (p<0.001). The maximum threshold shift in Group1 was greater than 20 dB and in Group2, it was less than 10 dB, at 8000Hz. Again, this result was statistically and clinically significant (p<0.001). Finally, the mean corpuscular volume (MCV)was higher in Group1 than Group2, and (p=0.001). CONCLUSION The results suggest that the level of iron is related to aminoglycoside ototoxicity. More iron can create more ototoxicity, and iron deficiency may inhibit aminoglycoside ototoxicity. An increase in MCV may be due to higher serum ferritin and an indication of more ototoxicity.