|Year : 2022 | Volume
| Issue : 3 | Page : 231-237
Prevalence of iodine deficiency and urinary iodine excretion among school-going children in a Southern District of Karnataka – A cross-sectional study
Ramachandra Kamath1, Rajashree Kotabal1, K Kruthika1, Sharvanan E Udayar1, Jagadish Gangani2
1 Department of Community Medicine, Kodagu Institute of Medical Sciences, Government of Karnataka, Madikeri, Karnataka, India
2 Department of Community Medicine, Shri Atal Bihari Vajpayee Medical College and Research Institute, Government of Karnataka, Bengaluru, Karnataka, India
|Date of Submission||21-Apr-2022|
|Date of Decision||09-May-2022|
|Date of Acceptance||21-May-2022|
|Date of Web Publication||28-Dec-2022|
Dr. Sharvanan E Udayar
Department of Community Medicine, Kodagu Institute of Medical Sciences, Government of Karnataka, Madikeri, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Iodine deficiency is a major public health problem, which leads to impaired neurodevelopment, particularly in early life and is the single most preventable cause of mental retardation and brain damage in children and fortunately, it is preventable. Aims: To estimate the prevalence of goitre among school children in Kodagu District and to estimate the urine iodine excretion and salt iodine content in a subsample. Patients and Methods: A cross-sectional study was conducted among school children of 6-12 years in the Kodagu district. Sampling was done by population proportionate to size cluster sampling method with 2700 study participants, 540 salt samples and 270 urine samples. Results: Out of 2700 study participants, the prevalence of goitre was 15.50%. Students of Madikeri Taluk, rural area students, 11-year-old students, Consumption of Goitrogens among students show significant association with goitre after multivariate logistic regression analysis. Urinary iodine excretion test shows 0.36%, 1.80% and 12.99% of the participants had severe, moderate and mild iodine deficiency, respectively. Conclusion: The prevalence of goitre was high indicating that it is an endemic area. Activities such as periodic surveys, provision of iodised salt and intensified monitoring and further evaluation of the IDD programme is obligatory to reduce the goitre rate.
Keywords: Goiter, iodine deficiency, school children, urinary iodine
|How to cite this article:|
Kamath R, Kotabal R, Kruthika K, Udayar SE, Gangani J. Prevalence of iodine deficiency and urinary iodine excretion among school-going children in a Southern District of Karnataka – A cross-sectional study. J Med Evid 2022;3:231-7
|How to cite this URL:|
Kamath R, Kotabal R, Kruthika K, Udayar SE, Gangani J. Prevalence of iodine deficiency and urinary iodine excretion among school-going children in a Southern District of Karnataka – A cross-sectional study. J Med Evid [serial online] 2022 [cited 2023 Feb 1];3:231-7. Available from: http://www.journaljme.org/text.asp?2022/3/3/231/365879
| Introduction|| |
Iodine is a vital micronutrient for human nutrition. The deficiency of Iodine has been documented as a public health problem in India and is the single-most preventable cause of mental retardation and brain damage in children. Deficiency of iodine results in impairment of thyroid hormone synthesis, which in turn leads to hypothyroidism, and a series of functional and developmental abnormalities grouped under the heading of 'iodine deficiency disorders' IDD.
The prevalence of goitre increases with the severity of iodine deficiency and becomes endemic in populations where the intake of iodine is less than 10 μg/day.
Worldwide, around 740 million people are affected by goitre and 2.2 billion people reside in iodine-deficient regions, thus they are under risk of IDD. The surveys conducted by the Central and State health Directorate, ICMR, and Medical institutes define that the states where the prevalence of IDDs is more than 5% then that state is considered endemic to IDD.
Fortification of salt with iodine is the broadly accepted preventive strategy to battle against IDD. It has been made mandatory to iodise all forms of table salts in India to eliminate the deficiency of iodine. The government of India has relaunched National IDDs Control Programme (NIDDCP) in the year 1992 with the goal to reduce the prevalence of IDD to non-endemic level. It has been noticed that after the implementation of NIDDCP, India, has made considerable progress towards IDD elimination.
Enlargement of the thyroid gland is the common manifestation of IDD and goitre survey is used as diagnostic means to identify areas of IDD. School-age children are an especially functional population group for the assessment of IDD, both because of their physiological vulnerability and their ease of access through schools.
Iodine nutrition status in any population is generally detected by urinary iodine (UI) concentration, the goitre rate, serum thyroid-stimulating hormone and serum thyroglobulin. Among these, UI is most often used as parameter to determine iodine nutrition.
Many studies have been conducted to estimate the IDD problem in different parts of India but only a few studies have been conducted in southern Karnataka. Such studies will be very helpful for the expansion of intervention measures in iodine-deficient areas. Kodagu is located in the hilly region of the southern part of Karnataka. It is eminent that goitre is more prevalent in hilly regions and possibly due to iodine deficiency in the soil and water compared with plain areas. To find out the prevalence of goitre in the Kodagu district, a descriptive cross-sectional study was conducted among the (6-12 years) school-going students from the selected schools from all talukas of Kodagu district.
With this background, the current study was conducted to estimate the prevalence of goitre among school-going children in the Kodagu district and to estimate the urine iodine excretion (UIE) and salt iodine content in a subsample population.
| Materials and Methods|| |
The total population of Kodagu district is 5.5 lakh. The total population of 6–12 years is 54,733. A cross-sectional was conducted among school children of 6–12 years age group in the Kodagu district from November to December 2019. Sampling was done by population proportionate to size and the cluster sampling method was applied. Villages for the survey were selected using available data for all districts from Registrar General Office. These were listed in a table and the cumulative population was calculated. A sample of 30 villages was selected from the district and 90 children of the age group of 6–12 years from every school of the selected village were included as per the operational manual for the district IDD survey.
It was concurred to collect the baseline information and clinical examination for goitre among 2700 children. Among 2700 children every 5th child was included in the survey to collect the salt sample for the estimation of iodine content that accounts for 540 children and urine sample was collected among every alternate child in 540 children for the estimation of UIE which accounts for 270 children. Ethical clearance was obtained from the institutional ethics committee (Ref: KoIMS/IEC/15/20-21).
Medical examination of children between 6 and 12 years age group for goitre prevalence (n = 2700 children)
Testing of salt samples by volumetric analysis method for the estimation of iodine content (n = 540 salt samples)
Testing the urine samples by UIE method (n = 270 urine samples)
The assessment for the prevalence of goitre among school children was done using a pre-tested semi-structured and pre-validated questionnaire. Written consent was obtained from School headmaster/principal and parents before examination and salt/urine sample collection. Interview was done to collect the demographic data and also by consulting the appropriate school records and later clinically examined for the presence of goitre.
From the clinical point of view, the diagnosis of goitre based on inspection and palpation of the neck. The goitre is then classified into three grades.
- Grade 0 – No palpable or visible goitre/no goitre
- Grade 1 – A mass in the neck that is consistent with the enlarged thyroid, that is palpable but not visible, when the neck is in normal position. It moves upwards in the neck as the subject swallows. Nodular alteration (s) can occur even when the thyroid is not enlarged/goitre palpable but not visible
- Grade 2 – A swelling in the neck that is visible when the neck is in normal position and is consistent with an enlarged thyroid when the neck is palpated/goitre visible and palpable.
Estimation of urinary iodine excretion
Urine samples from 10% of the study population were collected and analysed for median UIE content using Titration by thiosulphate and The Sandell Kolthoff reaction.
Estimation of Iodine content in salt
Salt samples were collected from 20% of the study participants and the concentration of iodine was measured. The iodine content of iodised salt is estimated by a process called iodometric titration.
Severity as a public health problem will be assessed using the obtained goitre prevalence and median UIE levels.
The study tool was translated to the local language and back-translated in English to check for consistency and was validated on a 5% sample and suitable changes were made in the final pro forma.
Data were entered into Microsoft Excel data sheet and analysed using Statistical package for Social Sciences - version 22 software (IBM Inc.Armonk,New York,United states of America). Categorical data were represented in the form of frequencies and proportions. The Chi-square test or Fischer's exact test was used as test of significance for qualitative data. Multivariate logistic regression analysis was performed to calculate the adjusted odds ratio with a 95% confidence interval (CI). The value of P < 0.05 was considered statistically significant after assuming all the rules of statistical tests.
| Results|| |
The present study was conducted among 6–12 years age group school children of Kodagu district. The total study population comprises 2700 children among them equal proportion (1350) of boys and girls were included.
The total goitre rate in the present study was 15.50% indicating mild public health problems. Among a total 15.50% goitre prevalence, 14.8% of them had grade 1 goitre and 0.7% of them had grade 2 goitre.
In our study, the percentage of goitre was more among 11 years (21.8%) age group students, followed by 10 years (18.1%) old students compared to other age group students and this showed statistically significant. There was no major difference between the goitre rate among girls (15.6%) and boys (15.4%) and it does not show a significant association also [Table 1].
Our study showed a statistically significant association between the prevalence of goitre and factors such as, students from the rural area and from Madikeri taluk. Similar association was found with respect to the literacy status of the parents. Statistically significant results were noted among the students who consume goitrogens, rock salt and the salt which was stored near the fire [Table 2].
In the present study, 8.55% of the study participants consumed <15 Parts Per Million of iodine in their salt and 92.11% of the study participants consumed >15 Parts Per Million of iodine in their salt.
When we calculated the UIE among the study participants showed, 0.36% had UIE <20 (severe iodine deficiency), 1.80% had UIE 20 to 49 (moderate iodine deficiency), 12.99% had UIE 50 to 99 (mild iodine deficiency), 85.19% had urine iodine estimation 100 to 199 (optimal) [Table 3].
In the present study, after eliminating the concomitant variables, multivariate logistic regression analysis of the significant factors of goitre result shows that the presence of students of Madikeri Taluk (AOR: 5.896, 95% CI: 3.784 – 9.188), rural area students (AOR: 1.692, 95% CI: 1.346 – 2.127), 11 years old students (AOR: 1.598, 95% CI: 1.067 – 2.395), consumption of goitrogens (AOR: 1.371, 95% CI: 1.086 – 1.731), were significantly associated with goitre in school children [Table 4].
|Table 4: Multivariate logistic regression analysis of risk factors of goitre|
Click here to view
| Discussion|| |
The prevalence of goitre in our study was found to be 15.50%. Similar results (15.29%) were seen in a study done in the Baramulla district of Himalayan region among school children (6–12 years). A comparative study done among Mysore and Kodagu districts in 2014 showed that the overall prevalence of goitre in the Kodagu district was 19.01%. Results of the present study when compared to the study done in 2014 indicated that the population in the Kodagu district is possibly in the transition phase from iodine deficient to iodine sufficient nutrition.
In this study, 84.5% had Grade 0, 14.8% had Grade 1 and 0.7% had Grade 2 goitre. A similar study done in the Bharuch district of Gujrat among primary school children showed that the prevalence of goitre was found to be 23.2% with grade 1 – 17.4% and grade 2 – 5.8%. A study done in Baramulla district of Himalaya an region among school children (6–12 years) showed that the prevalence of Grade 1 goitre was more than 20-fold higher than Grade 2 goitre which was similar to our study results. The prevalence of grade 1 goitre was more than ten folds higher than grade 2 goitre in a goitre survey done among school age children (6-12 years) in Northern India.
In the present study, the prevalence of goitre was more among 11 years of age group students compared to other age group students and this shows a statistically significant association between age distribution and goitre. This may be due to as the age increases the goitre prevalence also increases. The highest prevalence of goitre was seen among school children of 12 years of age in the Northern Himalayan region. The prevalence of goitre was observed to be 13.8% with the highest rate was seen among school children of age 8–10 years in Northern India (45.8%). A study done in the Kashmir division reported that the prevalence of goitre in children aged 6–12 years was 18.9% where in 18.5% of children had grade 1 goitre and 0.4% had grade 2 goiter.
The prevalence of goitre among boys was 15.4% and among girls 15.6% and there was no significant association between gender and goitre. However in a study done in the Northern Himalayan region showed that females had a higher prevalence of goitre (17.58%). The relationship of goitre prevalence with gender was statistically significant. Another comparative study was done among two districts in south Karnataka showed higher prevalence among females than males, which was more evident in grade 2 goitre cases.
In the present study, the prevalence of goitre was more in Madikeri (20.3%) compared to other taluks which show statistically significant results and this could be due to its hilly territory with low levels of iodine in the soil and water. Furthermore, the inaccessibility of iodised salt in certain distant hilly regions. In contrast to this, a study done in the Kodagu district shows the highest prevalence of goitre in Somvarpet taluk (24.53%) and the lowest prevalence in Madikeri taluk (8.90%).
The present study demonstrated that the prevalence of goitre was more among students of rural areas (21.3%) compared to urban areas (12.8%) and this shows a significant association. A comparative study done in West Bengal shows similar findings.
The present study revealed that the prevalence of goitre was more among the students who were consuming crystalline salt (20.2%) compared to the students who were consuming powder salt (14.2%). Similar findings were noted in the study conducted in rural areas of Tamil Nadu where the prevalence of goitre was more among the students who were consuming non-iodised salt which was commonly crystalline salt.
In the current study, prevalence of goitre was more among illiterate parents compared to educated parents. This is consistent with the findings from the study done on schoolchildren of southern Ehiopia and the study done in Goba town, Southeast Ethiopia.
The occurrence of goitre in the present study was more among the students who consume more goitrogens compared to other students. This was consistent with the study done in the Anchar district, Eastern Ethiopia.
The present study showed that significant association between the storage of salt near the fire and away from the fire this may be due to iodine content in salt was lost due to inappropriate handling during storage that is keeping salt container near the fire and this is consistent with the results of a study done in Sri Lanka.
A study done in Tamil Nadu to track the progress the IDDs showed that the proportion of households consuming iodised salt was 65.7% and those using adequately iodised salt were 18.2%. In a study done in Ethiopia among school-going children showed that only 29% of the households had adequately iodised salt and 71% of the households were consuming inadequately iodised salt. However, in our study, 92.11% were consuming adequately iodised salt which is very contrast when compared to the above studies.
In the study 0.36% had severe iodine deficiency, 1.80% had moderate iodine deficiency, 12.99% had mild iodine deficiency and 85.19% had optimal. Similarly, study done among school children in Dhaka district of Bangladesh showed that only 16.79% of participating children had sufficient iodine nutrition status based on UI excretion. Among 83.21%, who had deficient iodine nutrition, 42.64% were moderately deficient, 22.26% mildly deficient and 18.30% severely deficient.
Strengths and limitations
Even though the study was well organised with an adequate sample size and majority of casual factors were taken into consideration to find out association, still it has a few limitations like palpation of the thyroid gland just not accurate enough to diagnose the goitre which could have introduced bias in the study and genetic factors which also play a major role in the causation of goitre were not taken into consideration.
| Conclusion|| |
The prevalence of goitre in our study was found to be 15.50% indicating that it is an endemic area, where goitre remains a significant public health problem. Our study confirms the presence of goitre as the age increases. Factors such as high altitude area, rural area and consumption of goitrogens shows responsible for the occurrence of goitre in school children. To eliminate IDDs, there is an obligatory need of periodic surveys to assess the magnitude of the IDD in context to the impact of the iodised salt intervention, providing iodised salt to the public, intensification, monitoring and evaluating the IDD programme, which are essential to achieve sustainable elimination of IDD in India. Effects of geographical locations, dietary factors, storing salt techniques, cooking techniques and interaction of iodine with other nutrients are some areas where further research can be done in future.
We sincerely thank our beloved Dean and Director, Dr. Cariappa KB, Kodagu Institute of Medical Sciences, Madikeri. We express our humble, sincere indebtedness to Dr. (Mrs.) Rajini, Deputy Director (Nutrition), Directorate of Health and Family Welfare Services, Bengaluru. Of special value in this work was the most appreciative support and co-operation of Medical Social Workers of Community Medicine, Statistician, Lab Technician, Kodagu Institute of Medical Sciences, Madikeri for their contribution.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]