This study was conducted at Damoh district of MP from May to June 2016 among school-going children aged 6-12 years. Ethics approval was obtained from the Institutional Ethics Committee of the All India Institute of Medical Sciences, Bhopal, India. The written assent was obtained from children and consent was obtained from their legal guardians after explaining them the purpose of study.

Thirty schools were selected from Damoh district by cluster sampling technique, using the method of Probability proportionate to size sampling in each school. A sample of 90 children (45 boys) were selected from each school. Thus a total of 2700 children were clinically examined for goiter by technical persons specially trained for the survey [7,8]. The household of every fifth child selected from the sample of 90 children in the earlier steps, was visited for collection of salt sample. These salt samples were tested qualitatively on the spot with MBI kits (MBI Kits Intt., Chennai) and iodine concentration was recorded. On-the-spot urine samples were collected from every alternate child from those 18 selected children in the previous step, for the estimation of UIE level by wet digestion method from each school, and the samples were transported to an accredited laboratory at Human Nutrition Unit, AIIMS, New Delhi. Socio-demographic information, goiter examination and on-the-spot urine samples were obtained during school visits and salt samples for estimation of iodine were obtained by visiting corresponding houses of the selected children. 150 households and 30 shopkeepers were interviewed with the help of pre-designed semi-structured interview guide to understand the knowledge and practices on iodized salt during house visit to collect the salt samples.

Data were entered into Microsoft Excel 2010 and analyzed using Epi Info version 7.2.1.0. The key analytic outputs were presence of Goiter (Grade I and II), house-hold with ‘inadequate iodized salt’, and child with ‘insufficient UIE’. The UIE <200 µg/L was considered as ‘insufficient, and <15 ppm of Iodine in household salt was considered as household with ‘inadequate iodized salt’ [1,9].

A total of 2700 primary school children (aged 6-12 years) were examined for TGR. Overall, its prevalence was 2.08%, with Grade I as (45) 1.67% and Grade II as (11) 0.41%. About one-fourth (27.6%) households were consuming inadequately iodized salt. Out of 270 urine samples, median UIE level was 175 µg/L, and 25.9% children had insufficient UIE in their samples. The frequency of insufficient UIE was more in older children (age 10-12 years), females, children of Hindu religion, OBC and SC caste (Table I). All the households interviewed (150) were using packed salt, and all 30 shopkeepers interviewed were selling packed salt. Majority of families [117 (78%)] and shopkeepers [20 (66.7%)] were aware about iodized salt.

On the basis of UIE level, the proportion of children with mild, moderate and severe iodine deficiency were (45) 17%, (23) 8% and (2) 0.7%, respectively. Total (76) 28% children were found to be ‘Adequate’ in Iodine Nutrition. The proportion of children with more than adequate Iodine intake was (27) 10%, and (97) 36% of children had toxic levels of iodine in urine.

The present study found a TGR of 2.08% in Damoh district, MP, which suggests that this district is no more an endemic area for IDDs [6]. About one-fourth population is having ‘Iodine deficiency’ but at the same time about half (46%) of the population had more than adequate iodine intake.

Studies from different parts of globe have also reported iodine toxicity associated with USI [10-12]. The limitations of the study were that the clinical evaluation of goiter might have led to misclassification of grades of goiter, and that we could not compare the prevalence of IDDs of district with previous years as this information was not available.

On the basis of present study, we emphasize on repeat surveys to assess IDDs and the impact of iodized salt once in every 5 years in the districts. There has to be inbuilt mechanism in the program to monitor iodine toxicity.

Acknowledgements: Department of Education for the support during data collection. Prof Umesh Kapil, Human Nutrition Unit, AIIMS, New Delhi for providing laboratory support for urinary iodine analysis.

Contributors: All authors have contributed, designed and approved the study.

Funding: Department of Public Health and Family Welfare, Government of Madhya Pradesh; Competing interest: None stated.