The Effect of Iodized Oil Administration on the Impaired Hearing of Iodine Deficient Schoolchildren

Hearing loss and auditory disturbances may be present in both iodine deficient and hypothyroid children. The aim of this study was to determine the effect of iodine supplementation on the auditory threshold in iodine deficient children. 54 schoolchildren of the Kiga village, an area of severe iodine deficiency were studied before and one and three years after injection of 480 mg iodized oil. Goiter was graded according to WHO classification. Serum T4, T3, TSH and thyroglobulin concentrations and urinary iodine levels were measured. Audiometry was performed with a pure tone audiometer. There was a significant rise in serum T4 and significant decrease in the prevalence and severity of large goiters, and in serum TSH and thyroglobulin concentrations, one and three years after intervention. Before iodine supplementation, hearing was abnormal in 44% of schoolchildren. Mean hearing threshold was 15.4±6.0 prior to, and decreased to 13.9±6.0 and 10.1±4.7, dB, one and 3 years after, intervention, respectively (P<0.001). Hearing thresholds above 15 dB were detected in 45, 14 and 10% of pupils prior to, and one and 3 years after intervention, respectively (P<0.001). It is concluded that iodine supplementation improves auditory thresholds in previously iodine deficient children.