Evaluation of hearing functions in patients with euthyroid Hashimoto's thyroiditis

Acupuncture treatment for Hashimoto's thyroiditis: An exploratory randomized controlled trial

Background

Hashimoto's thyroiditis (HT) has a high incidence rate and unresolved clinical symptoms. Although Hand Yangming Meridian Penetrating Acupuncture has been used to treat thyroid diseases in China, there is no randomized controlled trial (RCT) on HT.

Methods

This exploratory RCT aims to preliminarily evaluate the efficacy, safety, and feasibility of Hand Yangming Meridian Penetrating Acupuncture in the treatment of HT. Included subjects were randomly assigned to the acupuncture group and the waiting treatment group at a ratio of 1:1. Subjects in the acupuncture group received 16 weeks of acupuncture treatment, followed by a 16-week follow-up observation phase. Subjects in the waiting group received thyroxine supplementation for 16 weeks, followed by 16 weeks of compensation treatment. Serum thyroid peroxidase antibody (TPOab) and thyroglobulin antibody (TGab) levels were the main indicators, and Thyroid-Related Patient-Reported Outcome short form (ThyPRO-39), MOS Item Short Form Health Survey (SF-36), and Hospital Anxiety and Depression Scale (HADS) scores were also recorded.

Results

In total, 58 subjects were included. After 16 weeks of treatment, there was no statistical difference in the changes in TPOab levels between the two groups, but the TGab level in the acupuncture group was significantly lower than in the waiting group (difference: -141.97 [95 % CI: -222.4 to -61.5], P = 0.011). Moreover, the total ThyPRO-39 and SF-36 scores were statistically different between the two groups (PThyPRO-39 < 0.001, PSF-36 = 0.005). There was no statistical difference in HADS between the two groups.

Conclusions

Hand Yangming Meridian Penetrating Acupuncture may be safe and feasible for HT hypothyroidism to improve symptoms and reduce TGab levels.

Trial registration number

This trial was registered at Acupuncture-Moxibustion Clinical Trial Registry: AMCTR-IOR-19000308 (ChiCTR1900026830, https://www.chictr.org.cn/searchprojEN.html).

Audiological evaluation (128-20,000Hz) in women with autoimmune thyroiditis: The role of antibodies vs. l-thyroxine deficiency

BACKGROUND AND AIM

Although sensorineural hearing loss may have different aetiologies, we focused on autoimmune hearing loss since it may be reversible with corticosteroid therapy; this entity is sometimes associated with systemic autoimmune diseases. Hashimoto's thyroiditis or chronic autoimmune thyroiditis shows antibodies and may be harmful to hearing thresholds regardless of hypothyroidism effect. To date this effect has not been sufficiently studied and never with extended high frequencies. The aim of this work is to study by age groups whether hearing thresholds in the human auditory range (128-20,000Hz) are affected in Hashimoto's disease.

MATERIALS AND METHODS

Two groups of 128 patients affected by Hashimoto's thyroiditis were included. First group: patients with pathological antithyroid antibodies who do not need L-thyroxine treatment. Second group: patients controlled with L-thyroxine substitutive treatment. Audiometric threshold study comparing between the groups of patients and a group of 209 controls was performed. All patients underwent complete otorhinolaryngological examination, antithyroid antibodies, TSH, T₃ and T₄ blood levels, tympanometry, conventional pure-tone audiometry, and extended-high-frequency audiometry.

RESULTS

All patients were women. Both groups showed worst audiometric thresholds than the control group; both study groups showed worse hearing than controls, this difference was statistically significant in all frequencies. In the 8-20kHz frequency range, this difference was more than 10dB, and in the 9-16kHz and 20kHz range this difference was more than 20dB. When separated by age groups, in younger subjects (20-29 years) these differences were found in all frequencies, except for conversational frequencies (500-4,000Hz); between 30 and 49 years the difference is statistically significant in all frequencies; and from 50 to 69 years differences are found, especially in the conversational frequencies.

CONCLUSIONS

This first work studying the human auditory range in the chronic autoimmune thyroiditis or Hashimoto's thyroiditis confirms that hearing loss related to the autoimmune disorder predominates at extended-high-frequencies initially. But ends up involving all frequencies in pure-tone conventional audiometry, then it may be detected in routine clinical tests. These results support the role of extended-high-frequencies audiometry to diagnose subclinical hearing loss in patients affected by Hashimoto's thyroiditis.

Audiological Patterns in Patients with Autoimmune Hearing Loss

INTRODUCTION

The aim of this study was to illustrate clinical and audiological patterns of hearing impairment in patients with autoimmune hearing loss (AIHL).

METHODS

Fifty-three patients with AIHL were retrospectively recruited, and a tapering schema of steroid treatment was administered in all these patients. The diagnosis of AIHL was essentially based on clinical symptoms, such as recurrent, sudden (sensorineural hearing loss [SSHL]), fluctuating, or quickly progressing (<12 months) SSHL (uni-/bilateral), in association with the coexistence of autoimmune diseases, high antinuclear antibodies (ANA) and the presence of human leukocyte antigen (HLA) B27, B35, B51, C04, and C07. Logistic regression analysis was applied to correlate the clinical data and laboratory features of AIHL with final outcomes.

RESULTS

The onset of AIHL was mainly progressive (49%), followed by SSHL (39.6%) or fluctuating (11.3%). The pure-tone audiogram showed more commonly a downsloping pattern (42.6% of ears), but also an upsloping, flat, cookie-bite, or inverse cookie-bite shape. Bilateral progressive AIHL was more frequently simultaneous (23 patients) than heterochronous (4 patients). Nineteen patients (35.8%) showed a favorable response to steroid therapy. The presence of recurrent, bilateral SSHL versus recurrent, unilateral SSHL had statistically negative effect on hearing recovery (OR = 0.042, p < 0.05). The heterochronous bilateral SSHL may have better prognosis than simultaneous bilateral SSHL (OR = 10.000, p = 0.099). The gender, age, concomitant autoimmune disease, high ANA, HLA alleles, tinnitus, and vestibular symptoms had no statistical effect on a favorable outcome of AIHL.

CONCLUSIONS

A bilateral, simultaneous, and progressive hearing loss combined with downsloping audiogram occurred more often in patients with AIHL. Bilateral simultaneous SSHL with recurrences represents the worse prognostic form of AIHL.

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.

Human Leukocyte Antigen (HLA) Influence on Prognosis of Autoimmune Hearing Loss

Background: To evaluate the effect of human leukocyte antigen (HLA) on hearing outcome in patients suffering from autoimmune hearing loss (AIHL). Materials and Methods: The diagnosis of AIHL was essentially based on clinical symptoms, such as recurrent, sudden, fluctuating, or quickly progressing (<12 months) sensorineural hearing loss (uni-/bilateral). The molecular typing of HLA alleles was achieved by using polymerase chain reaction procedures. Patients underwent a tapering schema of steroid treatment and audiometric features were recorded. A logistic regression model was used to identify which HLA typing alleles were statistically significant in patients’ response to treatment. Results: Forty patients with AIHL were found to be carriers of HLA B27, B35, B51, C4, C7, and DRB1*04 alleles. No statistically significant influence of HLA B27, B35, B51, C4, C7, DRB1*04 HLA alleles typing was detected for the prognosis of AIHL. In these patients, the onset of AIHL was mainly progressive (53.8%), 29.2% of them had moderate hearing loss, and most of the cases had both bilateral hearing loss (62.5%) and downsloping audiogram (40%). Conclusion: The presence of HLA B27, B35, B51, C4, C7, and DRB1*04 alleles had no significant effect on a favorable outcome of AIHL. However, larger samples of patients are necessary in order to improve the knowledge about the HLA influence on the clinical course of AIHL.

Dysphonia, arterial hypertension, diabetes mellitus, thyroid diseases, and noise complaints as probable factors associated with hearing loss among teachers

ABSTRACT Objective: to verify a possible association between hearing loss and dysphonia, arterial hypertension, diabetes mellitus, thyroid diseases, and noise complaints. Methods: a cross-sectional study involving 60 teachers, mean age 47.05 years. Pure-tone threshold audiometry was used to assess hearing, the voice questionnaire and voice acoustic evaluation were used for voice perception and quality, and the standardized questionnaire verified noise complaint and comorbidities. The statistical analysis was conducted with Mann-Whitney and Fisher's exact tests and multivariate linear regression. Results: there was a significant association between hearing loss and diabetes mellitus, hypertension, and thyroid disease (both p <0.0001), but there was no association between noise complaints and hearing loss in this population. The regression showed that dysphonia (p = 0.0311) and diabetes mellitus (p = 0.0302) are independent risk factors for hearing loss. A correlation was found between hearing loss and voice characteristics: roughness, breathiness, tension, and resonance. Conclusion: this study showed that hypertension and thyroid diseases are factors associated with hearing loss. In addition, dysphonia and diabetes mellitus are independent factors associated with hearing loss in teachers. These results show the need for policies aimed at promoting teachers’ health.

Association between SSNHL and Thyroid Diseases

The association between thyroid disease and sudden sensorineural hearing loss (SSNHL) has not been evaluated. We investigated the association of goiter, hypothyroidism, thyroiditis, and hyperthyroidism with sudden sensorineural hearing loss (SSNHL). Data from the Korean National Health Insurance Service-Health Screening Cohort were used. The 8658 SSNHL patients were matched in a 1:4 ratio with 34,632 controls for age, sex, and region of residence. Histories of goiter, hypothyroidism, thyroiditis, hyperthyroidism, and Levothyroxine medication were explored as possible factors influencing SSNHL development. Associations were estimated using conditional logistic regression analyses, adjusted for Levothyroxine medication use. Subgroup analyses were conducted according to age, sex, income, and region of residence. SSNHL patients had a higher rate of goiter occurrence (4.4% vs. 3.7 %, p = 0.001) and hypothyroidism (4.0% vs. 3.2 %, p < 0.001) than controls. Goiter and hypothyroidism were positively associated with SSNHL (adjusted OR =1.14 (95% CI =1.01–1.28), p = 0.043 for goiter and 1.17 (95% CI =1.03–1.33), p = 0.016 for hypothyroidism). In subgroup analyses, hypothyroidism or goiter was more prevalent in SSNHL patients than in controls. Lower-income subgroups showed associations of hypothyroidism and goiter with SSNHL. SSNHL patients were more likely to have goiter and hypothyroidism than normal individuals.

The Role of Anti-Endothelial Cell Autoantibodies and Immune Response in Acute Low-Tone Hearing Loss

OBJECTIVE

Immunity is associated with acute low tone hearing loss. However, the exact pathophysiology of immunity-mediated acute low tone hearing loss remains unknown. In this study, we evaluated the presence, therapeutic effectiveness, and immunopathological mechanisms of anti-endothelial cell autoantibodies (AECEs) in patients with acute low-frequency hearing loss.

MATERIAL AND METHODS

Forty-nine patients who were treated as inpatients having acute low-frequency hearing loss and additional symptoms, such as ear fullness, tinnitus, dizziness, or hyperacusis, were enrolled in this study. Serum samples from these patients were collected for laboratory serum autoimmunity detection, including AECAs, antinuclear antibodies, immunoglobulin, and circular immune complex. Therapeutic responses to combination therapy in short-term outcome and serum cytokine levels were compared between AECA-positive and AECA-negative patients.

RESULTS

Anti-endothelial cell autoantibodies-positive patients tended to show significantly less response to standard therapy compared with AECAs controls (P < .05). Moreover, some serum cytokine levels elevated in both AECAs- and AECAs+ groups. Positive ratio of interleukin-8 and concentrations of macrophage inflammatory protein-1α were found higher in AECAs+ groups (P < .05).

CONCLUSION

The results supported that AECAs might wield influence on the short-term outcome of acute low-tone hearing loss (ALHL) treatment. Furthermore, AECA-mediated acute low-frequency hearing loss possibly involved dysregulation of inflammation process and release of cytokines.

[Immune-mediated sensorineural hearing loss: prevalence and treatment strategies]

Autoimmune sensorineural hearing loss is a rare clinical entity which accounting for less than 1% in all cases with hearing loss. The prevalence of hearing loss in immune-mediated inner ear diseases, as shown in case reports or single-center statistics, varies widely. We reviewed the current literatures on the association between sensorineural hearing loss and autoimmune diseases, focused on the prevalence of hearing loss in different autoimmune diseases, treatments and challenges.

Is auditory brainstem response a prognostic factor in patients with sudden sensorineural hearing loss?

Background: Serum thyroid hormone levels are closely related to the normal functioning of the cochlea. However, the relationship between initial auditory brainstem response (ABR) results and levels of thyroid hormone remained unclear until we adopted ABR as a prognostic factor in Idiopathic sudden sensorineural hearing loss (ISSNHL) patients. Objective: This investigation aimed to elucidate the association between ABR and outcomes in patients with ISSNHL. Material and methods: Thirty-three patients presenting with unilateral ISSNHL underwent blood sampling and ABR tests on the day of admission. The mean latencies of the ABR results were compared among the groups which were classified by ISSNHL outcome, based on Siegel's criteria. The association between the ABR results and the thyroid hormone serum levels (TSH, T3, and free T4) were assessed. Results: The overall successful recovery rate was 60.6% (n = 20). The mean latencies of all the ABR parameters were not significantly different between the different treatment outcome groups (Mann-Whitney U test). Wave V latency, III-V interval and I-V interval were negatively associated with T3 serum levels. Conclusion: The results indicate that clinical caution should be exercised when conducting ABR tests without assessing thyroid hormone levels.

Untreated primary hypothyroidism with simultaneous rhabdomyolysis, pericardial effusion, and sudden sensorineural hearing loss: a case report

BACKGROUND

Hypothyroidism, one of the prevalent endocrine disorders worldwide, has a broad spectrum of clinical manifestations, from an asymptomatic condition to myxedema coma. Although the majority of patients with hypothyroidism have minor clinical symptoms, which are recovered with levothyroxine treatment, some patients occasionally do experience fatal complications. Here we report, for the first time, the case of a patient who had hypothyroidism with simultaneous occurrence of rhabdomyolysis with acute kidney injury, moderate pericardial effusion, and sudden sensorineural hearing loss.

CASE PRESENTATION

A 57-year-old man with a previous history of dyslipidemia and untreated hypothyroidism was admitted to the hospital due to shortness of breath, lethargy, lower extremity discomfort, and unilateral hearing loss. Laboratory results revealed rhabdomyolysis with acute kidney injury and severe hypothyroidism. We detected cardiomegaly without lung parenchymal infiltration on chest radiography and moderate pericardial effusion on transthoracic echocardiography. We performed pure tone audiometry and identified profound unilateral sensorineural hearing loss. Aggressive fluid resuscitation, levothyroxine treatment, and systemic and intratympanic steroid therapy alleviated the patient's severe hypothyroidism, rhabdomyolysis, and pericardial effusion; however, sensorineural hearing loss was not fully recovered.

CONCLUSIONS

Early recognition of life-threatening complications is important in patients with severe hypothyroidism to prevent adverse outcomes. This case suggests that hypothyroidism should be considered in patients who have rhabdomyolysis with acute kidney disease and pericardial effusion. Moreover, sudden sensorineural hearing loss should be kept in mind as a rare complication of hypothyroidism.

Phenomic Impact of Genetically-Determined Euthyroid Function and Molecular Differences between Thyroid Disorders

BACKGROUND

The thyroid plays a key role in development and homeostasis, but it has been difficult to establish causality with diseases and phenotypic traits because of several potential confounders.

METHODS

To determine the causal effect of euthyroid function, we conducted a two-sample Mendelian randomization study of euthyroid thyrotropin (TSH) and free thyroxine (FT4) levels with respect to 2419 traits assessed in 337,199 individuals from UK Biobank. Additionally, we investigated the molecular differences between hypothyroidism and hyperthyroidism using genome-wide data.

RESULTS

After multiple testing correction, sixteen traits appear to be affected by genetically-determined euthyroid TSH, including multiple thyroid-related traits, e.g., hypothyroidism (p = 2.39 × 10-17), height (p = 2.76 × 10-10), body fat distribution (impedance of whole body, p = 4.43 × 10-8), pulse rate (p = 2.84 × 10-8), female infertility (p = 4.91 × 10-6), and hearing aid use (p = 7.10 × 10-5). Moreover, we found a consistent genetic correlation between hypothyroidism and hyperthyroidism (rg = 0.45, p = 5.45 × 10-6) with several immune pathways shared between these diseases. Two molecular pathways survived multiple testing correction for specificity to hyperthyroidism, JAK/STAT signaling (p = 1.02 × 10-6) and Rac guanyl-nucleotide exchange factor activity (p = 4.39 × 10-6).

CONCLUSION

Our data shed new light on the inter-individual variability of euthyroid function and the molecular mechanisms of the two thyroid disorders investigated.

Autoimmune inner ear disease secondary to Hashimoto's thyroiditis: a case report

Autoimmune inner ear disease is an important yet incompletely understood cause of hearing loss which can present to different medical disciplines. Its diagnostic significance is indicated by the fact that it is a reversible medical condition if recognized early with an excellent response to immunosuppressive agents. Therefore, it should be considered in the differential diagnosis of hearing disorders especially in the context of another autoimmune disease such as Hashimoto’s thyroiditis.

Audiovestibular Symptoms in Systemic Autoimmune Diseases

Immune-mediated inner ear disease can be primary, when the autoimmune response is against the inner ear, or secondary. The latter is characterized by the involvement of the ear in the presence of systemic autoimmune conditions. Sensorineural hearing loss is the most common audiovestibular symptom associated with systemic autoimmune diseases, although conductive hearing impairment may also be present. Hearing loss may present in a sudden, slowly, rapidly progressive or fluctuating form, and is mostly bilateral and asymmetric. Hearing loss shows a good response to corticosteroid therapy that may lead to near-complete hearing restoration. Vestibular symptoms, tinnitus, and aural fullness can be found in patients with systemic autoimmune diseases; they often mimic primary inner ear disorders such as Menière's disease and mainly affect both ears simultaneously. Awareness of inner ear involvement in systemic autoimmune diseases is essential for the good response shown to appropriate treatment. However, it is often misdiagnosed due to variable clinical presentation, limited knowledge, sparse evidence, and lack of specific diagnostic tests. The aim of this review is to analyse available evidence, often only reported in the form of case reports due to the rarity of some of these conditions, of the different clinical presentations of audiological and vestibular symptoms in systemic autoimmune diseases.

Hearing loss in autoimmune disorders: Prevalence and therapeutic options

The objective of this study was to review our current knowledge relative to the correlation between sensorineural hearing loss (SNHL) and autoimmune diseases, focusing on the prevalence of hearing loss in different pathologies and possible therapeutic approaches. A review of the literature on hearing loss in different forms of autoimmune disease has been carried out, with emphasis on incidence and prevalence of SNHL. Therapeutic protocols have been assessed including both conservative medical and rehabilitative methods. Cochlear implant outcomes have been investigated. The prevalence of hearing loss in autoimmune and immune-mediated inner ear diseases, as referred by case reports or single-center statistics, is widely variable. More difficult is the evaluation of severe/profound SNHL, usually reported in relation to cochlear implantation. Though these patients represent ideal candidates for cochlear implantation, as they become deaf after years of hearing; the associated systemic disease, the specific damage on inner ear structures and the medication taken may influence the result of cochlear implantation. The main problem is the cochlear fibrosis or ossification that has been found to affect 50% of implanted ears in patients suffering from autoimmune and immune-mediated SNHL. Hence, in the presence of severe/profound SNHL earlier implantation may be indicated before post-inflammatory obliterative changes to the cochlea.

The effect of thyroid autoantibody positivity on the functions of internal ear

The objective of the study is to investigate if any significant difference exists in hearing thresholds and tympanometric examination results among patients whose thyroid antibody positivity was detected approximately 1 year or at least 5 years ago. Study population aged less than 40 years consisted of 17 patients who had thyroid antibody positivities for an average of 1 year (first group), 15 patients who were followed up for at least 5 years for thyroid antibody positivity (second group), and 18 volunteers (third group). Tympanometric examination results, stapes reflex, SRT, SD, and pure tone values were examined. When the second group and the third group were compared, significant results were obtained at hearing frequencies between 500 and 4000 Hz. When the first group and the third group were compared, only at 1000 Hz threshold significant results were obtained. During evaluation of hearing frequencies between 250 and 8000 Hz, significant results were not observed between the second group and the first group. When the first and the second groups were compared with the control group, significant results were obtained as for tympanometric examination findings and significant results were not observed between the second group and the first group. A significant difference was not detected as for the results of stapes reflex. Since thyroid antibody positivity affects the functions of internal ear, these patients should be more closely monitored. Since these effects become deeper in line with increased exposure to autoantibody positivity, variations in auditory responses should be more attentively monitored.

The association of obesity with hearing thresholds in women aged 18-40 years

An elevation in hearing thresholds and decrease in hearing sensitivity in adults, particularly due to aging, are quite common. Recent studies have shown that, apart from aging, various other factors also play a role in auditory changes. Studies on the association of hearing loss (HL) with obesity are limited in advanced age cases and present contradictions. In this study, the association between obesity and hearing thresholds in women aged 18-40 years has been assessed. Forty women diagnosed with obesity (mean age, 31.8 years) and 40 healthy non-obese female controls (mean age, 30.5 years) were included in this prospective study. Each subject was tested with low (250, 500, 1000 and 2000 Hz) and high (4000, 6000 and 8000 Hz) frequency audiometry. In the case and control groups, the average hearing thresholds at low frequencies were 16.03 ± 4.72 and 16.15 ± 2.72 (p = 0.885) for the right ear, respectively, and 16.15 ± 5.92 and 14.71 ± 3.18 (p = 0.180) for the left ear, respectively. The average hearing threshold levels at high frequencies were 20.70 ± 10.23 and 15.33 ± 3.87 (p = 0.003), respectively, for the right ear, and 22.91 ± 15.54 and 15.87 ± 4.35 (p = 0.007), respectively, for the left ear with statistical significance. This is the first report on the association of obesity with hearing threshold in women aged 18-40 years. We have demonstrated that obesity may affect hearing function, particularly that related to high frequencies. Hearing loss can be prevented by avoidance or control of obesity and its risk factors. Moreover, an auditory screening of obese cases at an early stage may provide early diagnosis of HL and may also contribute to their awareness in the fight against obesity.

Do antithyroid antibodies affect hearing outcomes in patients with pediatric euthyroid Hashimoto's thyroiditis?

OBJECTIVES

Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease in children. HT is a multifaceted disease with a variable clinicopathological presentation, including hearing impairment. It is known that hearing function is negatively affected in patients with thyroid disorders. The literature includes a very limited number of studies on hearing function in euthyroid pediatric patients with HT. The aim of this study was to determine the relationship between cochlear function and HT, independent of thyroid function.

MATERIALS AND METHODS

The study included 48 children and adolescents (42 females and 6 males) aged 9-18 years that were diagnosed as HT, and 30 gender- and age-matched healthy controls. Hearing was assessed via otoscopy, tympanometry, pure-tone audiometry, and measurement of distortion product otoacoustic emissions.

RESULTS

There weren't any significant differences in pure tone thresholds between the 2 groups based on pure-tone audiometry, except in the right ear at 6kHz and 8kHz. Distortion product otoacoustic emissions signal to noise ratios were significantly lower in the HT group than in the control group at 4 different frequencies (6kHz [left ear], 8kHz [left ear], 1.5kHz [right ear], and 6kHz [right ear]) (P<0.05). The signal to noise ratios at all frequencies were <6dB in 3% of left ears and 2.5% of right ears in the control group, versus 12.5% of left ears and 9.6% of right ears in the HT group. Distortion product amplitudes were significantly lower in the HT group than in the control group for both left and right ears at 1kHz, 1.5kHz, 3kHz, and 8kHz, and at 2kHz for left ears only (P<0.05).

CONCLUSIONS

The present findings show that cochlear function was lower in the HT group than in the control group. Accordingly, we think that hearing in patients with HT should be monitored periodically, even if their hearing thresholds are within normal limits. Thyroid autoimmunity appears to play an important role in a decrease in cochlear activity in pediatric HT patients.