Prevalence of goitre and autoimmune thyroiditis in schoolchildren in Delhi, India, after two decades of salt iodisation.

Delhi lies in the sub-Himalayan plains and the existence of iodine deficiency is well established. Iodised salt was introduced in Delhi nearly two decades ago. The aim of the present study was to determine the status of iodine nutrition in school-aged children and the prevalence of autoimmune thyroiditis. A total of 4,320 schoolchildren (2,218 [51.3%] boys) aged 10-16 years were studied. Goitre was detected in 396 children, an overall goitre prevalence of 9.2%. Of the 396 children with goitre, 112 (28.3%) had evidence of autoimmune thyroiditis (AIT). The median urinary iodine (UI) excretion in the study population as a whole was 14.6 microg/dl. The median UI in the group of children with goiter was 13.3 microg/dl, whereas UI in children with goiter and evidence of AIT was 16.6 microg/dl (p <0.01). Of the 112 children with AIT, 77 (68.7%) were euthyroid, 23 (20.5%) had subclinical hypothyroidism, eight (7.2%) had hypothyroidism and the remaining four (3.6%) had hyperthyroidism. UI was high in goitrous children with AIT, and in children with thyroid dysfunction. Further studies are needed to clarify whether the higher UI in goitrous children with AIT is causally related to AIT or is due to the inability of the diseased thyroid to trap available iodine efficiently.