Hearing loss in those with Thyroid Hormone Resistance

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Hearing abnormalities have long been described in congenital

hypothyroidism, but their incidence is controversial.

Thyroid hormone receptor beta is now known to be restricted to the

cochlea; TR alpha is also present in the vestibule, and deaf-mutism

in a person in whom resistance to thyroid hormone was caused by a

homozygous deletion of the TR beta gene shows the importance of

thyroid hormone and TR beta in inner ear development.

Significant hearing loss, predominantly conductive, was noted in 21%

of persons with resistance to thyroid hormone and in no persons

without resistance. Frequent ear infections can explain the defect

in two thirds of the patients, but about one third of persons with

resistance who had hearing loss had no history of ear, nose,

and throat infections.