ESPE Abstracts

Background: A high rate of hearing impairment has been reported in patients with congenital hypothyroidism (CH). However, this association has only been explored in a few studies with inconclusive findings.

Objectives: To assess the prevalence of hearing impairment among patients with CH and determine whether hearing impairment is related to delay in supplemental therapy, etiology of CH or other parameters.

Methods: Audiometry was undertaken prospectively for 65 patients with CH and 49 healthy patients aged 3 to 30 years. All patients with hearing impairments underwent otolaryngologist examination, and brain stem response audiometry was performed in patients with sensorineural loss.

Results: Hearing impairment was found in 18 patients (27.7%) with CH, among them 4 (6.2%) with sensorineural and 14 (21.5%) with mild conductive hearing loss. None of the controls had hearing loss. The etiology of CH in patients with sensorineural hearing was TPO mutation (two patients), ectopic sublingual thyroid (1) and thyroid agenesis (1). Among patients with conductive hearing loss, the etiologies of CH were ectopic gland (six patients), TPO mutation (4), thyroid agenesis (1), TSH resistance (1) and transient CH (2). In comparing patients with hearing loss to patients without hearing loss, no differences were found in time of diagnosis, initiation of L-T₄ therapy, screened TSH levels, gender, ethnicity or CH etiologies. Mean screened TT₄ levels were lower in patients with hearing loss (3.58 vs 5.21 μg/dl, respectively), but this difference was non-significant.

Conclusions: We found a high prevalence of hearing loss among patients with CH. Both sensorineural and conductive hearing loss were found, with a higher rate for the latter. Hearing loss was not related to the etiology of hypothyroidism or delayed initiation of therapy; nevertheless, it is possible that non-adherence to thyroid supplement therapy has a role in hearing impairment. Our findings indicate that every child with CH must undergo audiometry, and long-term hearing follow-up is required.