Prevention of Iodine Deficiency Disorders in Children in India – the Way Forward

Abstract

Iodine is a critical micronutrient necessary for the physical development and optimal function of the thyroid gland and the central nervous system in children. Iodine deficiency disorders (IDD) encompass a continuum of disorders commencing from fetal life (ranging from infertility, abortion, stillbirth, and infant mortality) and extending through childhood (neurocognitive disability and hearing and speech impairment) into adult life (endemic goiter and hypothyroidism) [1]. Children living in iodine deficient areas generally have lower IQ levels than those in iodine sufficient areas [2]. IDD is a major public health problem in India and is one of the major micronutrient deficiencies globally. There are no tests to confirm whether a child has sufficient iodine in his/her body. When IDD is seen in a large population, it is managed by safeguarding that the food that family consumes contains appropriate levels of iodine with salt iodization. Most IDDs do not have a cure and prevention appears to be the best method for control and eradication. The Government of India made universal iodization mandatory in the year 2005. The National Iodine Deficiency Disorders Control Program (NIDDCP) was revamped in 2006 to monitor IDD [3].The monitoring under NIDDCP is done customarily by goiter surveys in schoolchildren along with estimation of urinary iodine for assessing iodine nutritional status and estimation of iodine content of the salt in households. Total goiter rate (TGR) >5% among schoolchildren and median urinary iodine <100 μg/L are considered to be markers of a public health problem. In developed countries like USA a much lower cut-off of 50 μg/L for median urinary iodine is used. With the introduction of universal iodization of salt the magnitude of IDD has declined, but the problem still persists [4]. Surveys confirm that IDD is not limited to sub-Himalayan regions and even costal belt across India is significantly affected. Problems with salt iodization, storage and transport of iodized salt, usage practices and inaccessibility are major barriers in the implementation of the program with nearly 20% of the households consuming salt with inadequate iodine [5]. The school health surveys commissioned under the NIDDCP constantly monitor the status of iodization and the TGR and the various factors impacting the program in all the states. Recent surveys have confirmed a declining trend in the prevalence of goiter in schoolchildren. Some districts have been declared as iodine sufficient whereas others continue to remain mildly endemic [6]. At the same time the prevalence has been unacceptably high in some districts. In the current issue of the journal, Shetty and colleagues highlight the current status of IDD in India with special reference to goiter prevalence and interrelated components from coastal district inKarnataka [7].The goiter surveys have shown that goiter is more prevalent in girls especially in the peripubertal age. It is probablymuch easier to observe and palpate an enlarged thyroid, as the child grows older [7, 8]. Many children with goiter had adequate salt iodine content and some children with significantly low salt iodine content did not have goiter. Clinical hypothyroidism is present in some children with grade 1 goiter suggesting etiologies other than IDD. Prevalence of goiter despite adequate iodine supplementation cautions that we should be on the look out for other micronutrient deficiencies affecting iodine metabolism. A recent study in children suggested selenium deficiency negatively affects the thyroid metabolism of iodine-replete children [9]. Higher prevalence in 10–12 y old children especially girls suggests the coexistence of autoimmune thyroiditis (AIT). Most studies have not evaluated thyroid hormones or anti-thyroid antibodies in school goiter surveys. These imply that the children with goiter need amore detailed clinical evaluation including assessment of growth and development as well as pubertal status. They also need follow-up with tests for thyroid hormone * P. S. N. Menon [email protected]