Prevelance of Thyroid Disorders in Childhood in India

Introduction A endocrine disorders most commonly encountered in the pediatric age group, disorders of the thyroid gland are most frequent with hypothyroidism being the commonest. Goiter (thyromegaly) with or without alterations in thyroid function is not uncommon but hyperthyroidism is less frequent. The most pronounced effect of thyroid dysfunction in this age group is on growth and development but it also leads to metabolic abnormalities similar to those in adults. Thyroid hormones increase oxygen consumption, stimulate protein synthesis, affect carbohydrate, lipid and vitamin metabolism, and influence activity of other enzyme systems and growth factors. In the brain they promote cell growth, cell differentiation and induce neurotransmitter function. Their deficiency in fetal life and early infancy can lead to irreversible impairment of neurocognitive function emphasizing the crucial role of thyroid hormones on developing brain. As thyroid hormone-dependent effects on tissue maturation are age related and organ or tissue specific, the clinical consequences of thyroid dysfunction relate to age of the infant or child. Hypothyroidism after the age of three years, when most of the thyroid hormone-dependent brain development is complete, results in slow growth and delayed skeletal maturation.1 However, permanent effect on cognition and neurological development is not commonly reported. If hypothyroidism remains unrecognized during early childhood, physical growth potential can also be affected. Hyperthyroidism can induce rapid linear and skeletal growth and maturation; it can lead to craniosynostosis in infancy and other systemic effects which are related to increased metabolic activity due to excess of thyroid hormones. Approximately 100mg of thyroxine (T4) is secreted by the thyroid gland daily and about 90mg of iodide (15mg/kg) is the recommended daily intake during infancy and childhood with higher requirements in preterms.