Thyroid status two decades after salt iodization: country-wide data in school children from India

Country-wide evaluation of thyroid disorders in school children following two decades of universal salt iodization (USI) has not been carried out till date. This study was planned with aim to assess thyroid status of school children two decades after the launch of USI programme.

Population survey.

We collected data from 25 schools in 19 cities across five different geographical zones of India. Those children who were evaluated for anthropometry, and goitre status by palpation formed 'total population'. Children who consented to give blood samples were defined as 'study population'.

Serum free T3, free T4, TSH, anti-TPO antibody and thyroid ultrasound.

A total of 38,961 children aged 5-15 years formed total population. Goitre rate was 15.5% while thyroid hypoechogenicity was found in 4404 (11.3%) children. In the study population (13,790 children), 2258 (16.4%) had goitre, 505 (3.7%) had positive anti-TPO antibody titres, 1001 (7.3%) had hypothyroidism (TSH > 5.2 μIU/ml) and 41 (0.3%) had thyrotoxicosis (TSH < 0.1 μIU/ml). Among goitrous children, 203 (9.0%) had anti-TPO positivity, 365 (16.1%) had hypoechogenicity of thyroid and either of these were present in 488 (21.6%) children.

Endemic goitre in school children persisted nationwide, despite more than two decades of USI programme. Thyroid autoimmunity only partially explains the increase in goitre prevalence.