Hearing Impairment and Audiological Alterations in Euthyroid Hashimoto's Thyroiditis.

INTRODUCTION

Hearing loss may be associated with autoimmune diseases, but it was less studied in Hashimoto's thyroiditis (HT). We aimed to evaluate hearing impairment and audiological alterations in adults with euthyroid HT.

METHODS

Adult patients with euthyroid HT (normal thyroid functions, positive antithyroid peroxidase (anti-TPO)/anti-thyroglobulin, and sonographic findings) were compared with controls. We excluded pregnant or older patients (>40 years), those with a history of otological/audiological disease or surgery, otitis media, acoustic trauma, chronic illnesses, use of alcohol, cigarette, medications, rheumatoid factor, antinuclear, antimitochondrial, antiparietal, antineutrophil cytoplasmic, anti-smooth muscle, or antigliadin antibodies, abnormal biochemical or otological findings. Tympanometry which indicates tympanic peak pressure (TPP, daPa), acoustic reflex testing (ART), pure-tone average (PTA), and transient evoked otoacoustic emission (TEOAE) were performed. We grouped the participants according to ART (positive/negative), TEOAE (normal/undetected), and PTA (≤20/>20 decibel).

RESULTS

Air conduction thresholds on the right ear at 500, 4,000, 6,000, and 8,000 Hz, PTA, and the left ear at 250, 4,000, 6,000, and 8,000 Hz were higher in euthyroid HT (n = 36) than in controls (n = 40) (p < 0.05). We found less negative TPP and a higher ratio of negative ART in euthyroid HT (p < 0.05). Euthyroid HT predicted undetected TEOAE and increased hearing threshold on the right ear at 500 and 8,000 Hz (p < 0.001). TEOAE detected audiological abnormality at a higher rate. Anti-TPO was positively correlated with TPP and air conduction thresholds, except the right ear at 8,000 Hz.

DISCUSSION/CONCLUSION: Hearing and audiological tests may be impaired in euthyroid HT. We recommend close monitoring of audiological functions in these patients. TE-OAE more specifically indicates audiological abnormality.