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- How does selenium defi ciency and exposure to thiocyanate cause thyroid gland
atrophy in endemic iodine - defi cient areas?
Iodine defi ciency results in hypothyroxinemia and consequent increased TSH
drive leads to increased intrathyroidal hydrogen peroxide (H 2 O 2 ) production.
Glutathione peroxidase, a selenoprotein, protects thyroid gland from H 2 O 2 -
mediated injury to thyroid follicular cells. In the presence of selenium defi -
ciency, there is accumulation of intrathyroidal H 2 O 2 which results in follicular
cell damage and fi brosis. Thiocyanate not only competes with iodine for
sodium–iodide symporter in the thyroid gland but has also been shown to
induce follicular cell necrosis. - What is the treatment for endemic cretinism?
Endemic cretinism is a preventable disorder and optimal iodine supplementa-
tion prior to conception prevents the development of cretinism. Therefore,
effective strategies for iodine supplementation should be implemented in
iodine-defi cient areas. In myxedematous cretins, iodine therapy has been shown
to improve myxedematous features when initiated prior to the age of 3–4 years;
however L-thyroxine should be preferred in children with myxedematous cre-
tin. Neurocognitive defi cits do not improve either with iodine or L-thyroxine
therapy in myxedematous cretins. Rehabilitation is the mainstay of therapy in
neurological cretins.- How to supplement iodine for daily requirement?
Iodine is present in alluvium soil and seawater. Therefore, vegetations grown in
iodine-rich soil and food of marine origin are rich source of iodine. Because of
recurrent fl oods and consequent soil erosion, iodine is leached away from the
soil, and iodine defi ciency is prevalent in many parts of the world. To prevent
iodine defi ciency disorders in the community, iodine needs to be supplemented
through a vehicle which is widely consumed. This vehicle may be water, milk,
salt, wheat fl our, or bread. Common salt is universally and consistently con-
sumed; hence it is the preferred medium to deliver recommended daily allow-
ance for iodine. Potassium iodate (KIO 3 ), the most stable iodine compound, is
preferred to iodize common salt.- What are the precautions required for the optimal delivery of iodine from
iodized salt?
The following precautions should be observed while using iodized salt. Salt
should be purchased within 3 months from the date of manufacture and at the
time of purchase it should be crystal clear and white. It must be stored in a dry,
3 Thyroid Disorders in Children