Iodine deficiency assessment

One of the major determinant of success or failure of IDD elimination is certainly linked to the availability of a good health information system. The present review discuss some of the parameters of iodine deficiency assessment and some nutritional facts from Europe relevant both to the european as well as to the worldwide IDD elimination. 

Countries affected by iodine deficiency require to develop national programmes to assess the extent and severity of the problem. Once an IDD control programme is initiated monitoring and evaluation are required. There are three major components needed to meet this goal, namely determination of thyroid size and goitre prevalence, the determination of urinary iodine excretion, and the measurement of thyroid function, including serum TSH levels. 

Urinary Iodine Excretion (UIE) provides the best single measurement of iodine intake of the population and Should be used for initial and follow up assessment. For epidemiological studies, population and not individual levels are is required. To achieve this 40 casual samples from a particular group can be collected (may be collected from schoolchildren at the same time as the goiter is assessed). The values are expressed as a median. Median UIE in the population below 100 pg/1 indicate iodine deficiency. Thus median UIE 10 pg/1 means no deficiency, 50-99 pg/1 indicates mild, 20 9 pg/1 moderate, and <20 pg/1 severe IDD. 

WHO. WHO assessment of iodine deficiency disorders and monitoring their elimination. A guide for programme managers. 2nd ed. Geneva (Switzerland) World Health Organization 2001. 

Deficiency of iodine, a component of thyroid hormones, may result in goiter formation (see Chap. 73). However, not everyone with an iodine-deficient diet will develop a goiter. Thyroxine (T4) and triiodothyronine (T3) can be used to assess iodine status (see Table 135-8). Intravenous iodine supplements typically are not necessary except during long-term parenteral nutrition with minimal enteral intake. Iodine needs generally are met by cutaneous absorption of iodine from germicides (e.g., povidone-iodine) used in catheter care or consumption of iodized salt. " Use of povidone-iodine wiU likely decrease with the increased use of chlorhexidine for catheter care, and the need for iodine supplementation must be individualized. Iodine excess is rarely a clinical concern when thyroid function is normal. 

Anonymous (1994) World Health Organization. Indicators for Assessing Iodine Deficiency Disorders and Their Control through Salt lodization. Geneva WHO/UNICEF/ICCIDD. 

ViTn P, Martino E, Aghini-Lombardi E, et al. (1994) Thyroid volume measurement by ultrasound in children as a tool for the assessment of mild iodine deficiency. J Clin Endocrinol Metab 79 600-603. 

WHO (2001). Assessment of Iodine Deficiency Disorders and Monitoring their Elimination. A Guide for Programme Managers, 2nd edn., WHO/UNICEF/ICCIDD, Geneva, WHO (WHO/NHD/01.1). 

To assess a local populations iodine status, according to the WHO requirements, by measurement of Ul and estimation of nutritional iodine intake and TGP, we used a comprehensive scheme to evaluate iodine status (Brauer et al., 2005) in Leipzig, a previously iodine-deficient area (Gruning et al., 2001 Hampel et al., 1995). We combined the investigation of different sources of iodine and different... 

The validity of the duplicate portion technique may be problematic as the completeness of duplicate portions is often difficult to assess. However, the use of biochemical markers, such as plasma, serum and urine, may be incorporated into nutritional assessment studies to validate dietary surveys or confirm nutritional status. There are a number of different methods that can be used to assess iodine status and, in particular, for the determination of the severity of iodine deficiency. However, two main methods used for the assessment of iodine status are measurement of urinary iodine excretion and thyroid function tests (an indirect method of iodine sufficiency). 

Establishing links between acmal dietary iodine intake and iodine deficiency disorders relies on the availability of precise techniques to enable accurate estimation of nutritional intake. However, the evaluation of iodine intake is difficult, due to wide variations in the iodine content of food hence, obtaining an accurate assessment is not possible with food composition tables. This is particularly pertinent to vegans who consume a variety of unconventional foods not listed, or inconsistently listed, in such tables. 

Until the 1990s, total goiter prevalence (TGP) in school-age children was the primary indicator for the assessment of functional consequences of iodine deficiency in the population (WHO et al., 2001). Thyroid size was traditionally determined by palpation, but the reliability of this method is limited by high inter-observer and intra-observer variations. The measurement of thyroid size by ultrasound has therefore been an important step in the detection of mild-to-moderate iodine deficiency. International reference values for normal thyroid size are now available from iodine-sufficient children (Zimmermann et al., 2004). Because TGP is not a sensitive indicator of recent changes in iodine status in the... 

Until the 1990s, TGP in school-age children was the primary indicator for the assessment of functional consequences of iodine deficiency in the population. 

UI is now recommended by the WHO as the main indicator to assess iodine stams in a population, and to track progress toward the efimination of iodine deficiency. School-age children are the recommended population group for iodine intake surveillance. 

This chapter will discuss the physiology of iodine deficiency in pregnancy, in addition to outlining the magnitude of the problem and its assessment in clinical practice. 

The observations relating to iodine deficiency in pregnancy are firstly those concerned with maternal thyroid function and maternal goiter. Maternal urinary iodine (UI) excretion is the usual method of assessing iodine status in the population at risk or the individual, and is discussed below. Neonatal indicators of maternal iodine deficiency are goiter and neurointellectual impairment. 

Neonates, and especially preterm infants, are a population at risk of suffering the consequences of iodine deficiency because of the impact of neonatal hypothyroxinemia on brain development. We evaluate the possible association between mental development scores at different ages and iodine intake during the neonatal period. Sixty-seven preterm infants were subdivided into GA groups for data analysis. The mental development scores reported here are those of the Brunet-Lezine scale index for children (0-24 months of age). The children were tested at 6, 9, 12, 18 and 24 months of postnatal age, and results were corrected for their GA. The test assesses P, motor abilities and postural... 

WHO, UNICEF and ICCIDD. (2001). Assessment of the Iodine Deficiency Disorders and Monitoring Their Elimination (WHO/ NHD/01.1), WHO, Geneva, Switzerland, pp. 1—107. 

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