Effects of acute thyroxine depletion on hearing in differentiated thyroid carcinoma patients

Abstract

Introduction: Radioiodine ablation refers to the destruction of functioning remnants of normal thyroid tissue or metastatic foci remaining after thyroidectomy. Effective thyroid ablation requires adequate stimulation of thyroid-stimulating hormone. Our aim in this study was to evaluate the hearing changes of patients before ablation therapy in the iatrogenic hypothyroid period, which has been constituted with the purpose of treatment success and following the ablation therapy in the euthyroid period 1 month after the thyroid hormone (TH) replacement therapy was initiated. Materials and Methods: Patients who were diagnosed with thyroid cancer, treated with total/near-total thyroidectomy and referred for 131 I therapy or low-dose 131 I whole body scan were included in our study. Hearing tests as high-frequency audiometry, autoacoustic emission and tympanometry were made during hypothyroid and euthyroid periods on all the patients included in the study. Results: In the present study were enrolled 75 patients with a mean age of 46.6 ± 12 years (range: 19-69 years). In hypothyroid period, while there was not any hearing-loss in 124 of 150 (82.7%) ears of 75 patients; mild hearing-loss in 18 (12%) ears, moderate hearing-loss in 7 (4.7%) ears and severe hearing-loss in 1 (0.07%) ear were detected. In euthyroid period, while there was not any hearing-loss in 132 of 150 (88%) ears; there were mild hearing-loss in 11 (7.3%), moderate hearing-loss in 6 (4%), and severe hearing-loss in 1 (0.07%) ear. However, there could not be found any significant difference between hearing levels of patients before and after treatment ( P = 0.317). Conclusion: Although THs play an important role in the physiology of hearing, the hypothyroidism made in 4 weeks period causes serious damages on hearing functions of patients. However, with regard to temporary hearing losses that hearing levels could improved with treatment, we believe that hearing should also be questioned in the follow-up of patients with differentiated thyroid cancer.