Median Urinary Iodine Concentration and Associated Factors Among Children Age 6 to 59 Months in Central Highland of Ethiopia

Introduction: Mid Urine Iodine Concentration (MUIC) is one of the biomarkers that are typically used to measure the concentration of iodide found in plasma thyroxin in human being and used to predict the risk of Iodine nutrient deficiency at population level. This study aimed to assess MUIC and associated factors among children age 6 to 59 months in the Central highland area of Ethiopia after an over a decade of intervention of with iodized salt by Ethiopian Government.

reduced mental capacity, and goiter and in Africa alone; 260 million populations are under insufficient of iodine intake [2]. Iodine deficiencies potentially cause mental impairment and physical damage on children [3]. Iodine deficiency occurs in preschool children when iodine intake falls below the recommended levels /90μg [4]. Improving progress towards the sustainable elimination of IDD in Latin America and the Caribbean, East Asia and the Pacific regions showed that greater of 80% of the households have been consuming adequately iodized salt since 1990 [1]. World Health organization (WHO) recommended that the deficiency of iodine corrected by increasing iodine intake through fortified table salt that required four major components of implementing the strategies. Among these strategies are correction of iodine deficiency, surveillance including monitoring and evaluation, educate the public and inter-sectorial collaboration and advocacy and communication to mobilize public health authorities are frontline for the Control of IDD through the world [5].
According to WHO recommendation, urinary iodine (UI) as potential indicator with high acceptance for the assessment and monitoring for subclinical iodine deficiency [6]. However, median urinary iodine concentrations of 100-199 mg/l in samples from schoolchildren or adults indicate adequate iodine intake and optimal iodine nutrition [7]. Urinary iodine excretion reflects the average daily iodine requirement intake and is an important index for determining the concentration of iodide found in plasma thyroxin [6]. In Ethiopia, insufficient iodine intake remained pervasively high until 2011 when the country was recognized as the top burden of iodine-deficient in the world [1]. Ethiopia had developed strategies are currently insufficient to monitor and evaluate the national programs related to measuring progress towards the goal of eliminating iodine deficiency [3]. In the Ethiopia monitoring and evaluation of iodine deficiency is not done regularly. But a single finding showed that 99.17% of households (HHs) had met their requirement of iodine per person per day in central highland region in Ethiopia [8]. Concerning to knowledge and attitude of the HHs toward prevention of IDD and HH iodised salt utilization is required necessary to educate the public. Following the current report, this study intended to measure MUIC to determine the effect of iodised salt intervention since over a decade. The study intended to assess iodine status of children as a marker for the impact of intervention with iodized in eliminating IDD salt [8].

Study Design and Area
Community based cross sectional study was used to determine iodine deficiency using MUIC through ammonium persulfate analysis methods following evolution iodised salt intervention in Central highland region of Ethiopia in October to December 2018. The study area included Arsi and Bale provinces (Munesa, Asella, Limuna Bilalo, Digeluna Tijo, Honkolo Wabe) mountains areas and has an altitude of above 2400 meters and had history of annual mean rainfall of 2200 mm to 2350mm [9]. All children aged 6-59 months with their mothers from households registered were selected using systematic sampling to participate in the past survey of Knowledge and Attitude about Prevention of Iodine Deficiency Disorders (IDD) among Women in the study area in June 2018. Children aged 6-59 months from those women who were registered and participated in the previously survey of January to June 2018 were included in study.

Sample Size Estimation
Sample size was determined using G power computer software version 3.0 with the following assumptions:

Sampling Procedure
Multistage sampling method was used to select study subjects. Laboratory Procedure for iodine determination from mid urine a.
In first, for each specimen mixing urine procedure was made to suspend sediment. Demographic variables and nutritional status of children described and analysed using logistic regression models. AOR with 95% CI were computed to assess the presence and degree of association with the outcome variables. P-value less than 0.05 was used to declare a statistically significant association. Linear regression model was used to assess predictors for positive/ negative or no effect on children's MUIC and correlation was declared at beta coefficient (B) and 95% CI. All assumptions of linear regression analysis were considered as sign of model fitness.

Results
A total of 812 children participated in the study with a response rate of 98.9 % and 48.8% of study subjects were young children    Stunted growth (HFA Z score < -1) in children also had more than 2 times the risk of inadequacy of iodine nutrient compared to those children who had normal growth (AOR=2.35, 95%CI:1.44, 3.84).
Being female, stunted growth and using cow milk as the only option for complementary food were statistically significant predictors of risk for insufficient iodine nutrient among children.

Discussion
This study showed that the proportion of children that had adequate iodine nutrient was higher (88.2 %) than finding in the 2014 Cambodian Demographic Health Survey (CDHS) which was 36.3% [12]. Likewise, in the current finding the prevalence of mild (50 to 99 iodine nutrient insufficiency accounted to 11.8 % which was very lower compared to CDHS reported that 63.7% of children had UIC below 100 μg [12]. This difference could be from the time to the current finding was 11.8% [13]. On the other prediction of adequacy of iodine nutrient, of this study finding higher proportion children (88.2%) found with UIC between 100 and 200 μg/L compared with Norwegian children was 59% [13]. Therefore, estimating the success of long era iodised salt intervention in the population with holding adequate data through wide study area in diversified community and using applicable feasible-preferable method (A ammonium persulfate) in MUIC analysis were validated for accuracy of these findings [7]. In monitoring iodine status, median urinary iodine among young children remains the key defining indicator [14]. However, very few studies were conducted among young children age 6 to 59 months that are potentially risk group for iodine deficiency and indicator for the evaluation of the success for iodine intervention.
For instance, monitoring and evaluation has improved over the last decade, but many countries have still not implemented national monitoring systems and lack of literatures may be relay to the cost of MUIC analysis which rise a challenge for researchers working in developing countries. We thought that this finding will have a primary contribution of information on the MUIC among children age 6 to 59 months in Ethiopia which can be used for evaluating the effect of iodized salt intervention in this age group in Ethiopia (Table 3).

Conclusion
This study showed that the iodine status among children age 6 to 59 months was at good status. But few proportions of children had insufficient iodine status. Being female and stunted (short stature) were the major independent variables that predicted iodine insufficiency among these children. Future research should use for sensitive biomarkers including T3 and T$ to substantiate this finding.

Acknowledgement
We would like to express their gratitude to Jimma University for financial support and ethical approval. We extend our special grati-