Long-term sequelae of hearing impairment in congenital hypothyroidism

Rovet, Joanne; Walker, Wynsome; Bliss, B. P.; Buchanan, Lori; Ehrlich, Robert

doi:10.1016/s0022-3476(96)70329-3

Cited by 100 publications

(71 citation statements)

References 24 publications

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“…Transient hypothyroxinemia in the first week after birth is a risk factor for cerebral palsy in premature infants (89). Hypothyroidism during fetal and neonatal development may result in hearing impairment with an inability to distinguish particular sound frequencies (90), possibly resulting in future reading disabilities. Between 20 and 30% of hypothyroid neonates suffer residual hearing impairment despite early treatment (91).…”

Section: Iodine In Freshly Opened Containers Of Us Iodized Saltmentioning

confidence: 99%

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Dasgupta,

Liu,

Dyke

2008

Environ. Sci. Technol.

111

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Adequacy of iodine nutrition in the United States has lately been of concern. A major source of dietary iodine for the U.S. population is iodized salt. The U.S. Food and Drug Administration (USFDA) recommends 60-100 mg KI/kg salt, equivalent to 46-76 mg I/kg salt. All U.S. iodized salt contains 45 mg I/kg according to labels. We collected samples of table salt from freshly opened containers from U.S. volunteers. A sample was sent to us when the can was first purchased. Subsets of volunteers sent further samples when the salt container became halfempty through normal use and a further final sample when the container was nearly finished. We also looked at iodine distribution homogeneity within individual containers, loss of iodine from salt upon exposure to humidity and sunlight, and upon short-term heating (dry and in solution) as may be encountered in cooking. Measurements were made in 0.01% w/v salt solutions by induction coupled plasma-mass spectrometry with 72 Ge as an internal standard. The median and mean ((sd) I content in freshly opened top-of-the-can salt samples was 44.1 and 47.5 ( 18.5 mg/kg (n ) 88, range 12.7-129 mg I/kg) and geometric mean and standard deviation of 44.70 and 1.41. Fortyseven of 88 samples fell below the USFDA recommended I content while 6 exceeded it. The homogeneity in a single can of salt varied greatly: in 5 samples taken from the same container from different depths, the iodine content varied by as little as 1.2× (8.3% coefficient of variance (CV)) to as much as 3.3× (49.3% CV) from one container/brand to another. Iodine is significantly lost upon high humidity storage but light or dry heat has little effect. There is much recent literature on iodine sufficiency and uptake inhibitors; there is also much misinformation and disinformation. We review the relevant literature and discuss our results with reference to the United States.

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Section: Iodine In Freshly Opened Containers Of Us Iodized Saltmentioning

confidence: 99%

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Dasgupta,

Liu,

Dyke

2008

Environ. Sci. Technol.

111

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“…That in-utero and neonatal hypothyroidism result in impaired development of both hearing and mental function has been demonstrated in studies in various animal species, rodents in particular (Hebert et al, 1985;Goldey et al, 1995;Ruiz-Marcos et al, 1983). In congenital and acquired hypothyroidism in man, hearing deficits seem to be mostly of the sensorineural type, but conductive or mixed type deficits also occur (Rovet et al, 1996;Anand et al, 1989). This would imply multiple lesion sites, including the middle ear, cochlear and retrococlear sites.…”

Section: Discussionmentioning

confidence: 97%

Mild iodine deficiency is associated with elevated hearing thresholds in children in Benin

et al. 2001

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“…Debruyne et al (74) reported that of forty-five paediatric patients with congenital hypothyroidism, 20 % had some degree of deafness. Similarly, Rovet et al (75) reported that among a group of seventy-five children with congenital hypothyroidism, 20 % had persisting mild hearing impairment (either conductive, sensorineural, or both), whereas the prevalence was only 0·24 % in the general paediatric population. Moreover, these children scored lower on various language tests until late in childhood, indicating delayed speech acquisition and difficulties in comprehension.…”

Section: Various Investigators Have Reported An Association Between Tmentioning

confidence: 93%

Iodine deficiency, thyroid function and hearing deficit: a review

Melse‐Boonstra

Mackenzie

2013

Nutr. Res. Rev.

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Iodine deficiency affects an estimated 241 million school-aged children in the world. Little is known about iodine deficiency in relation to auditory function, except for the fact that deaf-mutism is one of the features of cretinism. In the present review, we documented the scientific knowledge on the role of iodine and hypothyroidism in the auditory system. We found that ear development and hearing function depend on thyroid hormones. Multiple pathways are involved in this, including both inner ear morphology as well as neurological processes. Conductive as well as sensorineural hearing loss is found in studies with animals that were rendered hypothyroidic. In humans, auditory impairment is reported frequently in relation to hypothyroidism, ranging from mild disturbances to severe handicap. Auditory impairment has been related more explicitly to congenital hypothyroidism than to acquired hypothyroidism. The critical period for thyroid function-related hearing maturation is the first and second trimesters of pregnancy. Although only a limited number of studies have directly investigated the relationship between iodine deficiency and auditory function, most studies point toward an association. However, evidence from good randomised controlled trials is lacking. Inclusion of auditory outcomes in iodine supplementation studies is therefore to be recommended, especially for trials in pregnancy. Hearing deficit is an invisible abnormality, but has major consequences for educational and social skills if not detected. In view of this, auditory impairment should be mapped in iodine-deficient areas in order to realistically estimate the magnitude of the problem.

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Long-term sequelae of hearing impairment in congenital hypothyroidism

Cited by 100 publications

References 24 publications

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Mild iodine deficiency is associated with elevated hearing thresholds in children in Benin

Iodine deficiency, thyroid function and hearing deficit: a review

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