Goiter remains as one of the major health problems particularly among the young children and pregnant women worldwide . Iodine is a crucial constituent of hormones formed by the thyroid gland and goiter is the most visible sequel of iodine deficiency in human life . Globally, two billion people are at risk of Iodine deficiency disorders (IDD) due to insufficient intake of iodine and about 266 million school-aged children are at risk of insufficient iodine intake related health problems .
Goiter is one of the most pathological manifestations of long term depletion of iodine storage in human body especially among children living in iodine deficient areas . It is caused mainly by inadequate intake of iodine containing foods and high consumption of goitrogenic foods such as cabbage, maize, sweet potato and millet. The goitrogenic foods contain thiocyanate and isothiocyanate that restrain thyroid iodide transport [4, 5]. Insufficient production of thyroid hormone in the body is also a risk factor for goiter formation, besides inadequate iodine intake .
Iodine deficiency during childhood would reduce cognitive, somatic growth and motor function [6, 7]. It has multiple adverse effects in humans, and these effects are best explained as iodine deficiency disorders. The most common outcome of iodine deficiency during childhood is developmental delay .
Despite the fact that the World Health Organization (WHO) stated goiter as the sole most preventable cause of mental retardation and brain damage its prevalence among the population of the world is still estimated to be 15.8% [4, 9]. The burden of goiter is more prevalent in low income countries like Ethiopia .
A complete review on Iodine deficient disorder which was conducted in 2012 reported that the Africa continent harbors the highest burden of goiter rate which was between 4.7 to 28% .
As a study shows about 62% of the total population of Ethiopia are at risk of Iodine deficiency disorder. In addition, an estimated 12 million school -age children in the country were exposed to in adequate iodine intake related health problems . Thus, Ethiopia is considered as one of the countries in the globe with most people vulnerable to in sufficient iodine intake.
This can be explained further by the 14% increase in the prevalence rate of goiter among the total population of Ethiopia between 1980 to 2009,i.e. from 26 to 40%. The high IDD related peri- natal death of about 50,000 per year in the country is another important indication for the severity and magnitude of IDD in the country [11,12,13].
Furthermore, the proportion of children with goiter ranged from 15 to 30% in different regions of the country. The accessibility of iodine that is supposed to have effect on the prevalence of iodine deficiency disorder in iodine deficient areas in Ethiopia are believed to be caused by many ecological and nutritional predictors. This could be further explained by the mountainous landscape of many of the regions in the country which could result in the washing away of important nutrients like iodine because of the likely occurrences of repeated erosions in the areas for many years .
As a result, crop growing of the areas could be either with very low or no iodine content. For instance, as the findings of a study conducted in Bale Zone of Oromia region on iodine content of edible salt, cereals and drinking water showed there was very low amount of iodine and high concentration of other goitrogenic minerals in drinking water of the area .
Among the most vulnerable population group, school age children are particularly important for the assessment of IDD due to their high vulnerability. Studies reported that the prevalence of goiter among school age children of a certain area is an indicator for the status of iodine consumption in the community [16,17,18,19,20,21,22].
Other studies conducted previously in different countries reported that the prevalence of goiter among school children aged from 6 to 12 years varies from country to country. For instance, it was reported as 19.8% in the Karnataka, India, 35% in Pakistan and 48.3% at Kashmir Valley, in India [16, 21, 22]. As a study conducted in 2007 reported the prevalence of goiter among school children aged 6–12 years in Ethiopia was 39.9% .
Universal salt iodization (USI) is one of the most cost effective development attempts that can have paramount importance in improving the economic and social development of a country. As the World Health Organization (WHO) report indicated, about70% of the population of the world had access to iodized salt at household level [7, 20]. But the Ethiopian Demographic Health Survey (EDHS) of 2011 report indicated that only 15% of the households had access to an adequate amount of iodized salt in the country [23, 24].
In addition, WHO recommended that if the Total Goiter Rate (TGR) which is equivalent to the number of goiters of grades 1 and 2 detected in a population divided by the total number of individuals examined is 5% and above among children aged 6–12 years, it is considered as public health significant problem [7, 13]. Moreover, the daily recommended dietary allowance of iodine for school aged Child or 6–12 years old in order to prevent goiter is about 120 μg [25, 26].
However, most of the people in Ethiopia including our study area, Chole district live in the mountainous areas that are more vulnerable to erosions and flooding as well as subsequent risk of prevalent iodine deficiency in the community.
Cognizant of the problem, the Government of Ethiopia had launched a five –year national plan to eradicate iodine deficiency and associated health problems by the year 2015 through the achievement of utilization of adequately iodized salt to 90% of the population in the country [10, 12, 23]. In addition, the Federal Ministry of Health designed a National Nutrition Program and Micronutrient Guideline, and endorsed a proclamation for ensuring the availability of iodized salt [12, 24], though significant changes have not been attained and updated data are still scarce [10, 24, 27, 28].
Furthermore, even though many efforts were undertaken to minimize the problem, goiter is still prevalent in Ethiopia mainly among children and women living in high land areas including our study area or Chole district. Assessing the burden of ID among the most at risk population segment or school children might have paramount significance to clearly understand the progress of the current interventions and also to plan for sound actions in the future based on timely and research- based evidence.
Therefore, this study was designed to fill the current research gap about the prevalence and associated factors of goiter among school children (6–12 years) in Chole District, Oromia region, Ethiopia.