1.1. Iodine deficiency disorders (IDD)

Iodine deficiency disorders (IDD) can cause delayed brain development, stunting and stillbirth, and affects humans throughout their life. IDD has been a focus for elimination by the World Health Organization (WHO) since it is a preventable disease through intervention of adequate iodine nutrition. Human residing in the mountain areas are prone to be iodine deficient since iodine is swiped down by rainfall towards the sea [1]. IDD is segregated into severe, moderate, mild IDD. Examples of symptom are goiter, retardation & cretinism (Figure 1). The iodine nutritional status of a population is usually determined from median urinary iodine of schoolchildren aged 8–10 years old [2]. Elimination of IDD may reflect the growth of more

Figure 1. Iodine deficiency disorders (IDD) symptoms, e.g. (A) goitre & (B) cretinism [image reproduced with permission of the rights holders, www.drsosha.com & Human Info NGO; credit is given to United Nations Administrative Committee On Coordination (Sub-Committee On Nutrition)].

intelligent generation to come since it was reported that babies with higher intelligent quotient (IQ) were born from mothers with adequate iodine nutrition during pregnancy [3]. Iodine deficiency may also affect the production of thyroid hormones since each of them need iodine to be covalently bound to the tyrosine backbone [4]. Lack of thyroid hormone production may lead to hypothyroidism and may affect many metabolisms in human body [5]. Thus, iodine is very vital to human growth and development.

#### 1.2. IDD elimination program

in fetuses and it is involved in the synthesis of thyroid hormones, one of the vital hormones in human body. Hence, with optimum iodine supplementation, it could lead towards more

Urinary iodine is the test in determining the baseline of a population's iodine nutrition before decision of implementing Universal Salt Iodization (USI) is made. It is also important to monitor the iodine nutrition of the population after USI has been implemented. Sampling for urinary iodine testing among school children is non-invasive and urinary iodine is a reliable biomarker for immediate iodine level in one's body. Although thyroglobulin is the biomarker for long-term iodine nutrition in a human, urinary iodine remains the chosen biomarker for the purpose of easier and cheaper way of estimation of iodine nutrition status worldwide. In ensuring the validity of urinary iodine tests results, quality control has to be implemented in the laboratory. In the subsequent sections of this chapter, the quality control plans and implementation are discussed for the benefit of urinary iodine laboratory managers and operators.

Iodine deficiency disorders (IDD) can cause delayed brain development, stunting and stillbirth, and affects humans throughout their life. IDD has been a focus for elimination by the World Health Organization (WHO) since it is a preventable disease through intervention of adequate iodine nutrition. Human residing in the mountain areas are prone to be iodine deficient since iodine is swiped down by rainfall towards the sea [1]. IDD is segregated into severe, moderate, mild IDD. Examples of symptom are goiter, retardation & cretinism (Figure 1). The iodine nutritional status of a population is usually determined from median urinary iodine of schoolchildren aged 8–10 years old [2]. Elimination of IDD may reflect the growth of more

Figure 1. Iodine deficiency disorders (IDD) symptoms, e.g. (A) goitre & (B) cretinism [image reproduced with permission of the rights holders, www.drsosha.com & Human Info NGO; credit is given to United Nations Administrative Commit-

intelligent population.

68 Quality Control in Laboratory

1.1. Iodine deficiency disorders (IDD)

tee On Coordination (Sub-Committee On Nutrition)].

IDD elimination program is carried out worldwide. Various interventions of iodine have been implemented including through iodized water and iodized salt. Intervention of iodized salt is the most cost-effective strategy in the elimination program. Iodized salt interventions require only investment of 5–10 cents/year per person [6]. In 20 years, iodization of salt had reduced the prevalence of IDD, whereby, in the year 1993, the number of 131 iodine-deficient had been reduced to only 31 countries in the year 2014. In 2014 also, 70% households had access to adequately iodized salt. Within the years 2009–2013, it was estimated that 50–86% of households are consuming adequately iodized salt, ranging from the least developed countries to East Asia and Pacific countries [7].
