Published Sep 25, 2026 | 10:59 AM ⚊ Updated Sep 25, 2026 | 10:59 AM
About 90 percent of families reported using iodised salt.
Synopsis: A nationwide study of 8,903 Indian schoolchildren found goitre prevalence has fallen to 10.3 percent after four decades of universal salt iodisation. However, prevalence varied across study centres, from 7.3 percent in Pune to 12.8 percent in Puducherry. Researchers also found adequate iodine levels, but persistent thyroid autoimmunity and subclinical hypothyroidism.
India rolled out universal salt iodisation decades ago to fight goitre. The strategy worked. Goitre among schoolchildren fell from 23.5 percent in 2003 to 10.3 percent today.
But a new study has found that while goitre prevalence went down, thyroid autoimmunity doubled.
Researchers screened 8,903 children aged 10 to 18 across eight regions of India, from Srinagar to Puducherry. They published their findings in The Lancet Regional Health – Southeast Asia, under the ICMR-SALT-T 1 programme.
“Iodine nutrition, thyroid function, and thyroid autoimmunity four decades after Universal Salt Iodisation in India: a cross-sectional study among schoolchildren,” reads the study’s title.
India launched the National Goitre Control Programme in 1962, spurred by the Kangra Valley experiment of 1956, which proved iodised salt controlled goitre in the Himalayan belt.
The Centre renamed and expanded the effort in 1992, rebranding it the National Iodine Deficiency Disorders Control Programme, built around universal salt iodisation.
Goitre prevalence dropped from 23.5 percent in 2003 to 17.6 percent in 2012, then to 10.3 percent in this latest survey.
“The significant reduction in goitre rate from 23.5% to 17%–10.3% and goitre size in adolescent school children of India over the last 3 decades suggest positive long-term impact of USI, despite persistence of mild persistence of goitre,” the authors write.
Urinary iodine concentration among children tested came to a median of 133.2 micrograms per litre, a figure the World Health Organization classifies as adequate for population iodine nutrition.
About 90 percent of families reported using iodised salt, and 89 percent of tested salt samples carried more than 15 parts per million of iodine.
“This is a huge progress comparing 2008 UNICEF report that stated that only 51% of the nation’s households were consuming adequately iodised salt,” the study notes.
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Researchers tested 5,726 children for anti-thyroid peroxidase antibodies, a marker of autoimmune activity against the thyroid gland. They found 10.4 percent tested positive, up from 4.4 percent recorded two decades earlier.
“There is significant increase in overall prevalence of autoimmunity as assessed by anti-TPO positivity from 4.4% two decades following USI to 10.3%,” the authors state.
Girls bore a larger share of this burden. They carried more than twice the odds of testing positive compared with boys.
Furthermore, children with goitre showed more than twice the odds of anti-TPO positivity compared with those without.
“Several hypotheses has been proposed to explain rise in autoimmunity seen with iodine supplementation and include increased immunogenicity of thyroglobulin, increased MHC-II expression, altered cytokine expression and modulation of the microbiota-gut-thyroid axis,” the authors write.
“Its cross-sectional design precludes causal inference between iodine status, goitre, thyroid dysfunction, and autoimmunity.”
Among 5,512 children tested for thyroid function, 13 percent showed subclinical hypothyroidism, a state where thyroid-stimulating hormone rises while thyroxine remains within range.
The authors put subclinical hypothyroidism at 4.3 percent after the first decade of the programme, and 6.8 percent after the second, though they caution against a direct comparison because age brackets shifted between surveys.
“Whether SCH seen with a prevalence of 2.9%–14.1% among adolescent children in various studies is clinically relevant and warrants treatment is not known and need to be explored in further studies,” the study states.
Overt hypothyroidism stayed rare, appearing in 1.4 percent of children with goitre and 0.3 percent of those without. Hyperthyroidism barely registered in either group.
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Earlier nationwide studies had linked goitre to poverty, with children from poorer households facing greater prevalence than those from wealthier ones.
“The disappearance of difference in the present study may be the result of improved nutrition in poor children, provided mid-day meals as a government initiative; and improved reach of iodised salts to poor households,” the authors write.
Two separate state interventions, salt iodisation and school meal provision, appear to have converged on the same outcome, narrowing a divide that persisted for years.
Goitre prevalence swung widely between the eight study centres, from 7.3 percent in Pune to 12.8 percent in Puducherry. Researchers flagged considerable heterogeneity between sites, a statistical signal that local conditions still shape outcomes despite a uniform national policy.
Children classified as obese carried significantly higher odds of both goitre and subclinical hypothyroidism than those with normal weight.
“An additional consideration is the transient changes in thyroid function seen at puberty and rising prevalence of childhood obesity,” the authors note, pointing to obesity levels in the study population that ran above the pooled prevalence reported in a recent meta-analysis.
The study places India’s achievement against a backdrop where even wealthier nations struggle with iodine intake. The authors point to the United Kingdom and Australia, both reconsidering salt iodisation policy amid renewed deficiency concerns.
“This indicates the impact of USI, given the situation that even developed countries like the UK and Australia are facing the problem of iodine deficiency and reconsidering the need for salt iodisation programme,” the study states.
Comparable rises in autoimmunity surfaced elsewhere too. A survey in Italy recorded an increase after 15 years of iodisation, and a study from China reported a similar anti-TPO positivity figure after two decades of follow-up. Other regions tell a different story: population studies from Tasmania and north-east Germany found no comparable shift.
The authors call for continued monitoring, alongside quality checks on the iodisation programme itself.
“USI, being a cost-effective, time-tested public health intervention needs continuation with quality control,” the authors write.
“USI and low salt intake in diet are not conflicting strategies and both should go hand-in-hand, while increasing awareness about the low iodine content of rock salt, which is in currently in vogue.”
The researchers list several constraints on their findings. The sample came from schools, using non-probability sampling, which limits how far the results extend to the national population. School selection followed government and administrative permissions rather than random selection.
The age bracket also narrowed compared with earlier surveys, which included children from age six, while this round started at age ten, complicating direct comparison across the three decades.
Urinary iodine testing relied on a single spot sample from a subset of participants, a method that captures a snapshot rather than sustained intake. Goitre assessment relied on physical examination rather than ultrasound, since field ultrasound use falls outside current government permissions.
“Potential confounders such as other dietary iodine sources, goitrogen exposure, micronutrient status, and pubertal effects were not comprehensively assessed,” the authors add.
Despite these limits, the researchers frame the work as a rare nationwide dataset on a subject that receives little sustained tracking in India.
“In the fourth decade of USI, Indian school-children demonstrate overall adequate iodine nutrition and high household coverage of iodised salt,” the study concludes. “Despite this, mild residual endemic goitre persists almost entirely comprising WHO grade I goitre. High rates of thyroid autoimmunity and thyroid dysfunction need future follow up studies.”
(Edited by Dese Gowda)
