(P25-029-25) Benefits and Concerns of Universal Salt Iodisation USI) in Indian Children Four Decades Following Iodisation Program in India

Objectives: Assess Goitre Prevalence, thyroid functions, thyroid autoimmunity and iodine intake among children four decades after launch of USI program in India.

Methods: This cross-sectional study evaluated 6906 children aged 10-18 years from six regions across India. Consent for blood tests was obtained in 4192 subjects. Urinary iodine excretion (UIE) and salt iodine estimation was carried out 1in 4 subjects. Total T3, T4, TSH, and anti-TPO Ab were measured using the Chemiluminescent Immunoassay (CLIA) technique. Spot UIE was determined spectrophotometrically using the Sandell-Kolthoff reaction to estimate daily iodine intake.

Results: The mean age of children was 13.8±2.1 years with boys to girls ratio of 1:1. The prevalence of goitre was 10.8% (grade1=10.7%) with significantly higher prevalence in girls than in boys (14%vs 7.7%, p< 0.001). Subclinical hypothyroidism and overt hypothyroidism was detected in 12.4% & 0.9% respectively with goitrous subjects having prevalence of hypothyroidism than non-goitrous (17.2% vs 11.1%, p< 0.001). Importantly, no significant difference was seen in the prevalence of hypothyroidism between boys and girls. TPO⁺ AB was observed in 10.5% of children with higher prevalence in girls than boys (13.8% vs 7.1%, p< 0.001) and in goitrous than in non-goitrous subjects (22.5% vs 11%, p, < 0.001). the median UIE value of 140.8 ug/L (IQR: 87.12-208.24) and the median iodine content in salt samples of 27.49 ppm (IQR: 23.26-31.72) were within normal ranges.

Conclusions: Persistent mild endemic goitre despite adequate iodine prophylaxis was observed in children even after four decades of USI. However, marked decline in goitre prevalence from 23.5% to 10.8%, reduction in gland size and adequate iodine prophylaxis over the last 3 decades affirms the beneficial impact of USI. Significant increase though, in the overall prevalence of subclinical hypothyroidism from 6.81 to 12.4% and likewise increase in anti-TPO Ab from 4.9 to 10.5% in the present study when compared with an earlier country wide study in the 2^nd decade, remains an unexplained concern.

Funding Sources: Indian Council of Medical Research