Urinary iodine

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. 

A 68-year-old man was treated for a subcutaneous infection of the thigh by subcutaneous irrigation with povidone iodine (71). Toxic plasma and urinary iodine concentrations were associated with abnormalities of cardiac conduction, lactic acidosis, acute renal insufficiency, hypocalcemia, and thyroid dysfunction. 

In 99 of 9320 newborns TSH concentrations were above the reference range (20 mU/ml) on the fifth day of life, but between the 10th and 21st day all these infants had normal TSH concentrations and normal thyroid function (38). In 76 of the newborns with hyperthyrotropinemia, urinary iodine excretion was significantly raised (above 16 pg/ml). Most of them were born in obstetric departments where iodophores were routinely used for disinfection during labor. 

Connolly, R. J. and Shepherd, J J., The effect of preoperative surgical scrubbing with povidone iodine on urinary iodine levels. Aust. N. Z. J. Surg. 42, 94—95. 1972. 

Fisher, D. A. (1989). Upper limit of iodine in infant formulas. /. Njdr. 119,1865-1868-Fumee, C. A., Pfann, C. A., West, C-, Kaat, E, Heidc, D-, and Hautvasi, J. (1995). New model for describing urinary iodine excretion Its use fur comparing different oral preparations of iodized oil. Am, J, CHh, Nutr. 61,1257-1262. 

Braverman LE, et al. Use of inductively coupled plasma mass spectrometry to measure urinary iodine in NHANES 2000 Comparison with previous method. Clin Chem 2003 49 1019-21. 

Slovakia and urinary iodine concentrations were similar in the worker and control groups (data not... 

Rhodifuse lode has been successfully tested in African villages where drinking water had very low iodine contents. Normal urinary iodine levels were measured after six months of supplementation. A significant regression in the prevalence of endemic goiter was observed among the population after one year. 

Caldwell, K. L., Jones, R., Hollowell, J. G. (2005). Urinary iodine concentration United States National Health and Nutrition Examination Survey 2001—2002. Thyroid. 15 692—699. 

An estimation of iodine level in a spontaneous urine sample is not representative of iodine intake over a one-week period, as urinary iodine concentrations vary daily by > 50% about the arithmetic mean of the weekly iodine intake (Anke et al. 2000, Bauch 1985). 

Delange F, De Benoist B and Burgi H (2002) Determining median urinary iodine concentration that indicates adequate iodine intake at population level. Bulletin of the World Health Organization 2002, 80 633-636. 

Hampel R, Goedalia A and Zollnee H et al. (2000) Continous rise of urinary iodine excretion and drop in thyroid gland size among adolescents in Mecklenburg-Westpommemfrom 1993 to 1997. Exp Clin Endocrinol Diabetes 108 197-201. 

There are various well-established biomarkers of intake and/or nutritional status of numerous food components (Margetts and Nelson, 1997 Wilett, 1998). In the case of iodine, a good measure of iodine intake is urinary excretion, because most (more than 90%) of iodine ingested is excreted in urine. Thus, the urinary iodine concentration, even in casual urine samples, is a good marker of iodine nutrition. Urinary iodine concentration varies with fluid intake, so these values have limited use for casual samples from an individual, but they are well-suited for assessing a population group, because individual variations tend to average out. 

XRF provides important information about the iodine stored in the iodine pool - a parameter that cannot be assessed by other methods, such as urinary iodine or uptake measurements with... 

Figure 6.5 The relationship of mean and median concentrations of serum thyroglobulin (Tg) to urinary iodine in general (a) and hospital (b) populations. Subjects were divided into groups based on their iodine intake, and the mean or median of serum Tg were calculated in total groups, and also in corresponding subgroups consisting of men or women.

Figure 13.10 Correlation between iodine content of tap water in 41 towns in Denmark and the average 24 h urinary iodine excretion in young men in each town. Source Pedersen et al., (1999) reproduced with permission.

Figure 28.5 shows the iodine concentrations in urine and milk from nonsmoking and smoking mothers, and in urine from their neonates. Whereas urinary iodine concentrations were not different between groups of mothers, the iodine content of breast milk and of neonatal urine was reduced to around 50% if the mother was a smoker. This effect of smoking varied with the cotinine concentrations in mothers, and with the levels of thiocyanate in serum from the mothers and in cord serum (Laurberg et al., 2004). 

Figure 28.6 Maternal smoking and neonatal iodine nutrition. Breast-milk iodine and infant s urinary iodine content expressed as fraction of the mother s urinary iodine concentration. Both are measures of iodine transfer from mother to child during breastfeeding. The infant s urinary iodine content is expressed as a fraction of miik iodine content and is an inverse measure of iodine retention in the infant. Reproduced from Laurberg et al., (2004) with permission.

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