An Assessment of Iodine Deficiency in School Age Children in Chitradurga District of Karnataka State – A Cross-Sectional Study

Introduction

Iodine deficiency is one of the important nutrition problems in India. The deficiency of this micronutrient leads to a wide spectrum of disorders from the intrauterine life extending through childhood and adult life with serious health and social implications¹ . Lack of Iodine in the diet leads to visible and invisible spectrum of health consequences collectively called Iodine Deficiency Disorders (IDDs)² . Iodine Deficiency Disorder (IDD) constitutes the single largest cause of preventable brain damage worldwide leading to learning disabilities and psychomotor impairment³.

People living in areas affected by severe iodine deficiency may have an intelligence quotient (IQ) of up to 13.5 points below that of those from comparable communities in areas where there is no iodine deficiency³ . It was estimated that 1.9 billion people from 130 countries are at risk of developing IDD. Globally, India has the largest number of children born vulnerable to iodinedeficiency⁴. In India, IDD has been identified as a public health problem with 200 million people at risk⁵.

When iodine intake falls below recommended levels, the thyroid may no longer be able to synthesize sufficient amounts of thyroid hormone. The resulting low level of thyroid hormones in the blood (hypothyroidism) is the principal factor responsible for damage to the developing brain and other harmful effects known collectively as “iodine deficiency disorders”.

Two major factors responsible for IDD are inadequate iodine intake and inadequate iodine utilization. The inadequate iodine intake may be secondary to low iodine content of the soil or inadequate iodine consumption in the diet⁶.

Iodine Deficiency Disorders are among the easiest and least expensive of all nutrient disorders to prevent. The addition of a small, constant amount of iodine to the salt that people consume daily is all that is needed. The elimination of IDD is a critical development issue, and should be given the highest priority by governments and international agencies³.

Considering this, the Government of India has started National Iodine Deficiency Disorders control program in 1992 to promote nationwide use of iodized salt. Under this program, iodized salt containing 15 ppm of iodine is made available to the beneficiaries. Most of the iodine absorbed in the body eventually appears in urine, so urinary iodine concentration is a good marker for estimating very recent dietary iodine intake⁷.

One of the objectives of NIDDCP is to conduct surveys to assess iodine deficiency disorders and the impact of iodized salt after every 5 years in the districts. As a part of IDD survey being conducted in various districts of Karnataka, IDD survey was conducted in Chitradurga District during February-March 2020 by Bangalore Medical College and Research Institute, Bengaluru under the guidance of Deputy Director (Nutrition), IDD cell,Directorate of Health and Family Welfare services. This study was conducted to study the prevalence of Goitre in children aged 6-12 years, to analyze the salt iodine level at consumer level and to determine the median Urinary Iodine Excretion among these children.

Materials and Methods

Chitradurga, a place with historical significance which is located to the North West 200 kms away from Bengaluru. It comprises taluks like Chitradurga, Molkalmur, Holalkere, Hiriyuru, Challakere and Hosadurga. The district has 22 Hoblies which comprises of 1063 villages looked after by 189 Gram Panchayaths.

As per the District IDD Survey Guidelines provided, a cross sectional survey was conducted in 30 villages/ wards of Chitradurga district during the time period of February-March 2020. All the doctors and field investigators which included the health staff were trained rigorously before the commencement of survey regarding clinical examination of goitre, salt and urine sample collection and transport. Initially, list of all the primary schools (government, private, aided) in Chitradurga district was collected from the DDPI of Chitradurga District. From the list, 30 primary schools were selected by Disproportionate Stratified random sampling with taluka as the stratifying unit. Necessary precautions were taken to avoid selection of 2 schools from the same village/ward. Consent was obtained from the school management to conduct the survey.

The respective BEO and ADPI were informed regarding the survey before visiting each school. Consent was obtained from the school management to conduct the survey. The school authorities were informed to request all the children aged 6-12 years to bring salt samples from their residence (3-4 teaspoon of salt in a plastic cover) on the day of survey.

On the day of survey, 90 children (45 boys and 45 girls) aged 6-12 years were selected by disproportionate stratified random sampling (class studying as the stratum) for clinical examination of goitre by doctors. All the children in the study group were physically examined by senior resident for the presence of goitre using WHO Classification.

Grade 0 – No palpable or visible goitre

Grade 1 – Palpable but not visible goitre

Garde 2 – Palpable and Visible goitre

20 salt samples (for laboratory Iodine level estimation) and 10 urine samples [3-5ml for estimation of Urinary iodine excretion] per school were collected by systematic random sampling of the above 90 children.

After the survey, a Health awareness session on IDD and also on the local context was given by a doctor to all the children present during the school visit in the schools wherever possible.

The salt samples collected were transferred into independent Ziplock covers, to avoid evaporation. Because this process artificially increases the concentration. Household salt samples were analysed for its iodine content using standard iodometric titration method.

The urine samples collected were transported in cold temperature conditions and were stored in refrigerator until they were analysed (within 24hrs of collection). Assessment of urinary iodine was done by an assay based on the Sandell-Kolthoff reaction. Based on the estimated levels of Urinary iodine excretion, children were classified into groups as described:

<20μg/L – Severe iodine deficiency

20-49μg/L- Moderate iodine deficiency

50-99μg/L – Mild iodine deficiency

≥100μg/L – Iodine replete state

A total of 2900 children comprising 1442 males and 1558 females were enrolled for the study. The investigators, interns, postgraduates were trained regarding the examination and grading of goitre, collection of salt samples and urine samples from the selected children. 650 Salt samples and 296 Urine samples were analysed.

Results

A. Demographic details:

A total of 2,900 children from 30 schools were screened for thyroid enlargement. A total 359 Urine samples were collected; of which only 296 were analysed for urinary iodine concentration. A total of 63 sample discarded due to low quantity, sediments or turbidity. Salts from 650 households were titrated for iodine content. 

B. Prevalence of goitre:

The overall prevalence of goitre was 10.3% of which 10% was Grade 1 and 0.3% was Grade 2 Goitre. Females (10.8%) had marginally higher prevalence of goitre than males (9.9%).

C. Urinary Iodine excretion estimation

A total of 296 urine samples were collected and analyzed for urinary iodine excretion (UIE). Range of UIE was 15-200 µg/L. Median UIE was found to be 150 µg/L implying IDD to be a public health problem in Chitradurga district. 269 (90.9%) of the study participants had normal UIE (>100 µg/L). Mild (50- 99µg/L), moderate (20-49µg/L) and severe (<20µg/L) iodine deficiency was seen in 17 (5.7%),8 (2.7%) and 2 (0.7%) of study participants respectively.

D. Household salt samples Iodine estimation

Analysis of iodine levels in 650 household salt samples showed that 640 (98.5%) samples were adequately iodized with iodine content of more than 15 ppm. Iodine concentration in 10 (1.5%) salt samples were less than 15 ppm.

Discussion

In this study, 50.28% girls and 49.72% boys participated, who belonged to age group of 6-12 years, the composition being age group of 6 to 9 years (1470, 50.68%) and 9 to 12 years (1430, 49.32%). The total goitre rate was 10.3%, the prevalence of grade 1 goitre being 10.0% (95% CI: 8.9-11.1) and grade 2 being 0.3% (95% CI: 0.1-0.6).

A study done in 2015 by Biradar et al in Ramanagar district goiter prevalence rate was 8.6%.⁹ And in Shimoga district survey in 2014 by Praveen et al, goiter prevalence was found to be 9.3%.¹⁰

A survey done by Sonavane R.S et al conducted in Gadag district in 2016 showed that the prevalence rate among 6-12 year children was 22.78%. Among this, 19.67% of children had grade 1 and 3.11% had grade 2 goitre, indicating that IDD is a severe public health problem in this district¹¹.In a survey at Bharuch district of Gujarat in 2012 by Chandwani H.R et al goitre prevalence was found to be 23.2% (grade 1 – 17.4%, grade 2 – 5.8%)¹²

In a survey done in 2005 at Belgaum district, prevalence of palpable and visible goitre was significantly high among females (21.8%) when compared to that of males (7.2%).¹³

And in survey done in Ramanagar district in 2015, females had higher prevalence compared to males in all the age groups but the difference was not statistically significant (0.437)⁹

After analysis of 296 urine samples, median UIE concentration was found to be 150.0 µg/L with a range 15 to 200.0 µg/L. The UIE below 100 µg/L was found in 5.7% (95% CI: 3.0-8.4). Proportion of children with a UIE between 50 and 20 µg/L was 2.7% (95% CI: 1.0- 4.4) and below 20 µg/L was 0.7% (95% CI: 0.0-1.7).

A study conducted in Gadag district showed that 39.63% of the salt samples had iodine concentration less than 15 ppm of which 15.93% had no iodine content in them showing that salt was iodized inadequately at the manufacturer level or due to loss of iodine during distribution process.¹¹

And in a survey done in 2015 in Ramanagar district 95.3% had iodine concentration ≥ 15 ppm at the household level.⁹

Analysis of level of salt iodized showed that 98.5% of the samples were adequately iodized with iodine content of >15 ppm (18.5% had 15-30 ppm and 80% had >30 ppm). As much as 1.5% of salt samples had iodine content between 5 and 15 ppm, showing inadequate iodination. None of the households was consuming salt with iodine content of <5ppm.

A study done at Gadag district, out of the 270 urine samples, it was found that 39.36% had moderate iodine deficiency and 38.88% had mild iodine deficiency. A study done in Himachal Pradesh in 2000 by Kapil et al, 3.5%,3.8%, 142% had urinary iodine excretion of <20, 20-49.9, 50-99.9 µg/L.¹³

Conclusion

The population in Chitradurga at present have iodine nutrition at par to the recommended, but continuous efforts from governmental and non-governmental organizations are needed to sustain the availability of iodized salt to keep iodine nutrition at optimum level.

The overall prevalence of goitre in the Chitradurga district is 10.3%. 98.5% of households were using adequately iodized salt (iodine concentration more than 15 ppm) and also the median Urinary Iodine Excretion (150.0 µg/L), which is more reliable in assessing the iodine deficiency disorder is within the normal limits.

Recommendations

1. Continue compulsory iodization of salt.
2. Intensified information, health education and communication activities through social media to school children, teachers and general public regarding the consumption of iodized salt and health problems of iodine deficiency.
3. The system of monitoring the quality of iodized salt provided to the beneficiaries should be strengthened and continued to progress towards the elimination of IDD.

Limitations of the study

1. In spite of the precautions taken (in form of intensive training to the investigating team), a small part of subjective bias in clinical examination for Goiter always exists.
2. It was not possible to analyze urine samples within 2 hours of collection because of longer travel duration between field and laboratory.
3. Presence of hormonal abnormalities related to thyroid may present as a neck swelling, which would lead to high goiter prevalence hence it needs to be differentiated from Nutritional thyroid disorder.

Acknowledgments

We would take this opportunity to acknowledge our deep sense of gratitude to the Director cum Dean of Bangalore Medical College & Research Institute, Bengaluru for permitting us to take up the IDD survey in the Chitradurga district.

We would also like to thank the State IDD cell, District Health Officer & District Surveillance Officers of Chitradurga district, wholeheartedly, for their support and guidance towards the survey.

We sincerely thank the Deputy Director of Public Instructions and Block Educational Officers of Chitradurga district whose support were instrumental in the smooth conduction of the survey.

The role of the Headmasters, teachers and the beloved students of all visited schools has been of tremendous importance and we are indebted to all of them for their help in completing the survey.

We extend our heartfelt gratitude to all the Faculties, Post graduates, Interns, Health Inspector students and office staff of Department of Community Medicine BMCRI, for all the support and co-operation for the survey.

Conflict of Interest

None.