Determination Of Iodine In Urine Research Articles

Methods for determining iodine in urine

Iodine deficiency remains a serious threat to public health worldwide, especially in children and pregnant women. Despite the apparent ease of iodine deficiency elimination with the help of a simple and highly effective strategy of compulsory salt iodization, the problem of iodine deficiency and iodine deficiency disorders remains urgent for public health in the Russian Federation. The most effective and informative way to study iodine status at population level is determination of iodine concentration in urine in epidemiological studies. This article presents a review of urinary iodine determination methods, as well as methodological recommendations for iodine determination, developed and adopted in National Medical Research Center for Endocrinology.

Relationship between iodine knowledge and dietary iodine intake in pregnant and lactating women: a cross-sectional study.

This study assessed the iodine knowledge of pregnant and lactating women and the relationship to dietary iodine intake and iodine status. The factors influencing iodine intake were analysed. Basic information and iodine knowledge were collected via a questionnaire. A FFQ assessed dietary iodine intake. The urinary iodine concentration (UIC) was measured using the arsenic-cerium catalytic spectrophotometric determination of iodine in urine (WS/T 107 -2016). A cross-sectional study involving pregnant and lactating women in Xinjiang, China was conducted. A total of 1181 pregnant women and 504 lactating women were enrolled in the study. The median UIC for pregnant and lactating women was 179·27 and 192·81 µg/l, respectively, and the dietary iodine intake was 407·16 and 356·89 µg/d, respectively. Of the pregnant and lactating women, 73·4 % and 82·5 % had medium iodine knowledge, respectively. In pregnant women, iodine knowledge and dietary iodine intake were positively correlated. High iodine knowledge and iodine education were shown to be protective factors for excessive iodine intake in pregnant women. This study demonstrated that the iodine nutritional status of women in Xinjiang was appropriate, and iodine knowledge was at a medium level, but there was confusion about iodine nutrition. Public education is needed to improve iodine knowledge and active iodine supplementation awareness among these populations of women.

Method for biochemical monitoring of iodine. Determination of iodide-ion in urine with an ion-selective electrode

Determination of iodine in urine is an important methodology in the assessment of thyroid disorders. This indicator is often used in epidemiological studies of the state of iodine nutrition of the population, since the widespread prevalence of human iodine deficiency diseases is directly related to the lack of iodine intake with food and water. A method for the iodide ion determination in urine has been developed based on preliminary preservation of the sample in the presence of a buffer solution containing 4.28 %wt. H2O2 at pH 6.8 – 7.5 and measurements of the potential of the iodide selective electrode directly in the preserved sample solution without separation of the interfering components. After mixing the sample with a buffer solution in a ratio of 1:1, it is preserved after 18 – 24 h and stored for at least 30 days. The interfering effect of macro- and micro-components has been studied. It is shown that the amount of sodium chloride in the sample should be taken into account only in studying the severe iodine deficiency (≤20 μg/liter) and urea does not affect the potential of the electrode. To assess the total effect of the organic components of urine, we compared the results of parallel determinations of iodine in the samples, one of which was preserved, and organics was removed from the second one by alkaline ashing. It is shown that the discrepancies in the results were random and did not exceed 11.3 %. Iodine loss has not been determined, the bias between the concentration of the introduced and found additives was insignificant. Thus, in a buffer solution with hydrogen peroxide, not only the preservation of the urine sample for a long time takes place, but also the interfering influence of inorganic and organic components of the sample matrix on the membrane of the ion-selective electrode is eliminated. Metrological evaluation of the developed methodology was performed, which showed the precision and trueness of the procedure. The method was tested in an experiment on the correction and enrichment of iodine in the diet of schoolchildren. The low cost, convenient and easy to use equipment, the possibility of long-term storage of preserved samples makes the method mobile and suitable for biochemical monitoring of iodine consumption and deficiency during a large-scale population survey.

Validation of a Spectrophotometric Method for Urinary Iodine Determination on Microplate Based on Sandell-Kolthoff Reaction

Iodine is an essential part of the thyroid hormones thyroxine and triiodothyronine. Therefore, it is essential to monitor iodine supply in a population. The biochemical marker for assessing and controlling iodine is urinary iodine concentration (UIC). This cross-sectional study included 180 pregnant women and 308 women of reproductive age. Urine specimens from 185 of the 488 volunteers were used. The urine specimens were measured using 2 methods: (1) ammonium persulfate digestion (APD), followed by the Sandell-Kolthoff (S-K) reaction modified on microplate for spectrophotometric detection; and (2) the reference method, inductively coupled plasma mass spectrometry (ICP-MS). The regression equation between the methods was ICP-MS method = 1.137*(APD S-K)-5.57. A Passing-Bablok regression showed no deviation from linearity (P = .17). A Bland-Altman plot showed a negative mean bias of -2.7%. The APD S-K reaction modified on microplate for spectrophotometric detection of UIC can be implemented into routine work. Its results are comparable to those of laboratories worldwide and to ICP-MS.

Assessment of the iodine deficiency severity in the population by serum thyrotropin levels in newborns

The problem of iodine deficiency (ID) and its adverse effects on the Ukrainian population, especially on children, pregnant and lactating women, does not lose its relevance. The aim. To assess the state of iodine status of the Northern Bukovіna population by the level of thyrotropin (TSH) in newborns during the years 2015–2020. Methods. Selective screening analysis to determine the serum level of TSH in newborns during 2015–2020 (a total of 47888 results), median ioduria and survey among pregnant women, determination of urinary iodine, ultrasonographic and hormonal profiles of 199 prepubertal children living in Northern Bukovina were performed. Results. During the analyzed period, there was a positive trend: the median ioduria in pregnant women increased from 89.8 μg/l in 2015 to 140.1 μg/l in 2020, the level of neonatal hyperthyrotropinemia above 5 μIU/l decreased to 5 % in 2020 (P < 0.001), there was an upward trend in the median ioduria among prepubertal children (60.4 ± 9.3 μg/l). The frequency of goiter was different and accounted for 25.3 % among children living in the mountainous area and it was much lower among children living in the plain areas and in Chernivtsi (15.6 % and 13.1 %, respectively, P < 0.05). Thyromegaly among children of the reference group occurred in 15.1 %. 12.3 % of children were characterized by TSH in the range of age standards, which were shifted towards its increase (4.23–5.00 μIU/l). Conclusions. The increase in the median ioduria and the decrease in the frequency of neonatal hyperthyrotropinemia above 5 μIU/l on the background of iodine supply has been found in the pregnant population. The indicator of neonatal hyperthyrotropinemia above 5 μIU/l can be used to assess iodine deficiency only in the population of pregnant women.

Analytical evaluation of the new Seal Autoanalyzer 3 High Resolution for urinary iodine determination.

IntroductionThe aim of the study was to evaluate the analytical performance of the new colorimetric, automatic analyser, Seal AutoAnalyzer 3 High Resolution (Seal AA3 HR) (Seal Analytical, Wisconsin, USA) for urinary iodine measurement.Materials and methodsThis study included testing of several analytical features of the method involving: imprecision (within-run %CVr, between-run %CVb and total laboratory precision %CVl), measurement uncertainty, carryover, linearity and method comparison, with 70 urine samples including the measuring range (20 - 700 µg/L).ResultsWithin-run, %CVb and %CVl of two control levels were 2.03% and 3.04%, 0.51% and 2.61%, and 2.09% and 4.01%, respectively. Carryover effect was less than 1%. The linearity was good in the range of urinary iodine values between 60 and 500 µg/L (R2 = 0.99). Good agreement of urinary iodine values was found between manual technique and Seal AA3 HR, using Passing-Bablok regression (y = 7.84 (- 3.00 to 15.29) + 0.95 (0.90 to 1.00) x) and Blant-Altman test. Cusum test for linearity indicates that there is no significant deviation from linearity (P > 0.1).ConclusionsThe obtained results proved excellent precision, reproducibility and linearity, comparable to the already used, manual method. The New Seal AA3 HR automatic analyser is acceptable for urinary iodine measurement with very good analytical characteristics and can be used for urinary iodine epidemiological studies of the Croatian population.

Current status of urinary iodine analysis and its clinical interest

Iodine deficiency especially during pregnancy causes neurological disorders in the fetus. Actually, about two billion people are suffering from iodine deficiency through the world. The assessment of iodine intake is based on the determination of urinary iodine in the target population. Despite the complexity of the urinary matrix, a reliable assay must be achieved. After a review of pathophysiological interest of urinary iodine, various techniques for its measurement and their analytical performance were analyzed in order to select a reliable technique and enhance results interpretation.

Iodine in autism spectrum disorders

ObjectiveThe aim of our study was to assess the iodine status of Polish boys with severe autism compared to their healthy peers and evaluate the relationship between urinary iodine, thyroid hormones, body mass index and Autism Spectrum Disorder (ASD) symptomatology. Subjects and methodsTests were performed in 40 boys with ASD and 40 healthy boys, aged 2–17 from the same geographic region in Poland. Urinary iodine (UI), free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), BMI, and individual symptoms measured by the Childhood Autism Rating Scale (CARS) were correlated.Validated ion chromatography method with pulsed amperometric detection was applied for the determination of urinary iodine after optimized alkaline digestion in a closed system assisted with microwaves. Results19 out of 40 children with ASD had mild to moderate iodine deficiency. Statistically significant lower levels of UI, fT3 and fT4 and higher levels of TSH were found in the autistic group when compared with the control group. Concentration of iodine in urine was negatively associated with clinician’s general impression for children between 11 and 17 years. Emotional response, adaptation to environmental change, near receptor responsiveness, verbal communication, activity level, and intellectual functioning are more associated with UI than other symptoms listed in CARS. ConclusionThe severity of certain symptoms in autism is associated with iodine status in maturing boys. Thyroid hormones were within normal reference ranges in both groups while urinary iodine was significantly lower in autistic boys suggesting that further studies into the nonhormonal role of iodine in autism are required.

Concentraciones de yodo en orina y en sal de consumo en mujeres entre 12 a 49 años del Perú

To determine the concentrations of iodine in urine and salt intake in women between 12-49 years of age in Peru. An observational and cross-sectional study was performed. During 2012 and 2013, the study included women aged between 12-49 years living in Peruvian households selected through a probabilistic, stratified and multistage sample. The determination of iodine in urine was performed based on the Sandell-Kolthoff reaction spectrophotometry. The qualitative evaluation of iodine salt was performed by Yoditest and the quantitative by volumetric analysis. Processing was performed using complex samples with weights. Medians, interquartile range and percentiles were obtained. The median urinary iodine levels in the participants was 250.4 ug/L. The regions with elevated median urinary iodine levels were: Moquegua (389.3 ug/L); Tacna (320.5 ug/L); Madre de Dios (319.8 ug/L), and Ucayali (306.0 ug/L); while Puno (192.9 ug/L); Piura (188.1 ug/L) and Tumbes (180.5 ug/L) had medians within ranges recommended by the WHO. The median urinary iodine in pregnant women was 274.6 ug/L (IQR: 283 ug/L).82.5% of the samples had iodine salt ≥30 ppm and 1.9% had values of 0 ppm. The median urinary iodine in Peruvian women is higher than recommended by the WHO and the majority of the samples had adequate iodine concentrations according to WHO recommendations.

Impacto de las acciones para la eliminación sostenible de la deficiencia de yodo en Cuba

To assess the effectiveness of the Sustainable Elimination of Iodine Deficiency Program through determination of urinary iodine and goiter prevalence. A cross-sectional study was conducted in Cuban school children aged 6 to 11 years old in 2011-2012. A stratified multistage sample was used in which the levels of iodine excretion in urine (urinary iodine) and the presence of goiter were determined. The median urinary iodine was 176.3 µg/L; 7.6% of the students showed some deficiency of iodine, only 2.2% were below 50 µg/L (severe deficiency), and 15.3% had urinary iodine above 300 µg/L. The percentage of school children with optimal iodine nutrition was 43.5%, this category showed a significantly higher frequency (p=0.03) in the mountain areas (52.5%). Goiter prevalence was 17.6% which corresponds to a mild endemic. However, in the mountain area the prevalence was 32.6% (severe endemic). The comprehensive analysis of the impact of iodine deficiency control measures assessed by urinary iodine excretion and goiter prevalence reflects that it is no longer a population health problem in urban and rural areas of Cuba, attributable to a proper process of salt iodization. Nevertheless, high goiter prevalence is still observed in the mountain area of Cuba.

Urinary Iodine is Associated with Insulin Resistance in Subjects with Diabetes Mellitus Type 2

Diabetes Mellitus (DM) is a major health problem worldwide and its prevalence in Saudi Arabia has reached 31.6%. Patients with diabetes mellitus are at an increased risk of thyroid disease. The purpose of this study was to examine the urinary excretion of iodine in type 2 DM (T2DM) patients, and to assess the clinical implication of iodine status on T2DM. A total of 266 adult Saudis aged 18-55 years (109 T2DM patients and 157 healthy controls) were randomly selected from the Riyadh Cohort Study. Subjects were assessed for anthropometry, morning blood chemistries including fasting glucose, and lipid profile; serum concentrations of leptin, adiponectin, resistin, insulin, aPAI, hsCRP, Ang II, TNF-α, TSH, T3, T4, urine creatinine, urine iodine were measured using specific assays. The concentration of urine iodine was significantly lower in T2DM than in healthy control subjects (84.6±2.3 vs. 119.4±3.4, p<0.001), which remained significant after creatinine correction and controlling for age (p=0.01). Furthermore, urinary iodine is negatively correlated with waist, hips, SAD, glucose, insulin, HOMA-IR triglyceride, resistin, angiotensin II (Ang II), and CRP, while it was positively associated with TSH. The decreased levels of iodine concentration in T2DM patients and its likely deleterious effects on metabolic functions calls for a systematic approach to thyroid disease screening in diabetic patients. Routine annual urinary iodine determination is recommended and should target T2DM patients at risk of thyroid dysfunction.

A simple micro-photometric method for urinary iodine determination

Urinary iodide concentration (UIC) is useful to evaluate nutritional iodine status. In clinical settings UIC helps to exclude blocking of the thyroid gland by excessive endogenous iodine, if diagnostic or therapeutic administration of radio-iodine is indicated. Therefore, this study established a simple test for the measurement of UIC. UIC was analyzed in urine samples of 200 patients. Samples were pre-treated at 95°C for 45 min with ammonium persulfate in a thermal cycler, followed by a photometric Sandell-Kolthoff reaction (SK) carried out in microtiter plates. For method comparison, UIC was analyzed in 30 samples by inductivity coupled plasma mass spectro-metry (ICP-MS) as a reference method. Incubation conditions were optimized concerning recovery. The photometric test correlated well to the reference method (SK=0.91*ICP-MS+1, r=0.962) and presented with a functional sensitivity of 20 μg/L. UIC of patient samples ranged from <20 to 750 μg/L (median 110 μg/L); 90% of the urine samples had iodide concentrations below 210 μg/L. The modified SK-test takes approximately 90 min for analyses of 20 urine samples compared with 27 h for ICP-MS. The photometric test provides satisfactory results and can be performed with the basic equipment of a clinical laboratory.

Rapid microwave digestion and microplate reading format method for urinary iodine determination

High temperature and long heating time can be considered the main drawbacks of the conventional digestion methods of urinary iodine determination. The aim of this study was to assess the usefulness of a microwave for digestion and decomposition of urine interfering substances. It may help for shortening the time and increasing the safety of the method. In this study, two digestion methods were tested on urine samples. Random urine samples were processed by conventional electrical heat as well as new microwave digestion methods. The urine samples were digested using the two methods mentioned, and then urinary iodine was determined using a colorimetric reaction according to the Sandell-Kolthoff reaction. In order to increase speed and precision of the test, a microplate ELISA reader was used. Sensitivity, precision, and comparison of the results were assessed in both of the methods. In the case of microwave digestion, only a 10-min period was needed for complete digestion of urine samples. The precision and recovery of the new digestion step was acceptable. Furthermore, comparison of final results of iodine content obtained using the microwave and conventional method showed good correlation. These results show that a microwave method for urine digestion is advantageous due to its safety and ease of use, and quick preparation of urine samples to eliminate interfering substances and release iodine. Thus, it can replace the conventional electrical heat digestion method.

Iodine deficiency status and iodised salt consumption in Malaysia: findings from a national iodine deficiency disorders survey.

A nationwide cross-sectional school-based survey was undertaken among children aged 8-10 years old to determine the current iodine deficiency status in the country. Determination of urinary iodine (UI) and palpation of the thyroid gland were carried out among 18,012 and 18,078 children respectively while iodine test of the salt samples was done using Rapid Test Kits and the iodometric method. The results showed that based on WHO/ ICCIDD/UNICEF criteria, the national median UI was 109 μg/L [25th, 75th percentile (67, 166)] showing borderline adequacy. The overall national prevalence of iodine deficiency disorders (IDD) with UI<100 μg/L was 48.2% (95% CI: 46.0, 50.4), higher among children residing in rural areas than in urban areas. The highest prevalence of UI<100 μg/L was noted among the aborigines [(81.4% (95% CI: 75.1, 86.4)]. The national total goitre rate (grade 1 and grade 2 goitre) was 2.1%. Of 17,888 salt samples brought by the school children, 28.2% (95% CI: 26.4, 30.2) were found to have iodine content. However, the overall proportion of the households in Malaysia using adequately iodised salt as recommended by Malaysian Food Act 1983 of 20-30 ppm was only 6.8% (95% CI: 5.1, 9.0). In conclusion, although a goitre endemic was not present in Malaysia, almost half of the states in Peninsular Malaysia still have large proportion of UI level <100 μg/L and warrant immediate action. The findings of this survey suggest that there is a need for review on the current approach of the national IDD prevention and control programme.

Methods for determination of iodine in urine and salt

Good quality data on iodine concentrations in urine and salt samples are indispensable for the efficient management of national salt iodisation programmes and for evaluating iodine interventions. Most of the analytical methods for urinary iodine concentration are based on the manual spectrophotometric measurement of Sandell-Kolthoff reduction reaction catalysed by iodine using different oxidising reagents in the initial digestion step. Other analytical methods include semi-quantitative methods, a microplate method, automated methods; and the technologically advanced methods include the inductively coupled plasma mass-spectrometer method. Iodine in salt is determined quantitatively by the titration method, colorimetrically by the WYD iodine checker or by a technologically advanced potentiometric method. Worldwide, titration is the method of choice because of its accuracy, ease of operation and low cost. Rapid test kits are suitable for qualitative use in situations where iodised salt need to be distinguished from non-iodised salt, preferably with titration back-up.

Determination of urinary iodine by inductively coupled plasma mass spectrometry

Background Mild iodine deficiency is endemic in many countries of Europe including Belgium. Fast, accurate and specific methods for quantification of urinary iodine are needed. We describe in this report a specific ICP-MS method for the quantification of urinary iodine. Method Samples and iodate calibrators were diluted 20 times into aqueous solution containing triton X-100, 1.5% HCl and 103Rh as an internal standard. Prior digestion or oxidation was not necessary. Results were compared with those obtained by Sandell–Kolthoff (S–K) spectrophotometric method. Results Comparison of both methods showed good agreement. The Passing–Bablok regression between both methods was ICP-MS=0.986 (S–K)−7.51. The Bland–Altman difference plot showed a small but significant mean difference of −13.3 μg/L for ICP-MS. The between-day coefficient of variation (CV) was 13% at 89 μg/L. Limit of detection was 4 μg/L and limit of quantification was 20 μg/L. No carryover effect has been observed on series containing up to 50 samples. Conclusion The ICP-MS method described here is fast, accurate and specific for the quantification of urinary iodine. Compared to the S–K method the urinary iodine concentrations measured by the ICP-MS method were slightly, but significantly lower. Consequently, the results of studies using S–K method should be compared with caution with those using the ICP-MS method.

Micromethod of Iodine Measurement in Vrine

Iodine concentration in urine is the direct quantity indicator of the current consumption of iodine in the population. The most widespread method of determination of iodine in urine is cerium-arsenic method with preliminary processing samples of urine using the solution ammonium persulfate. The purpose of work was to develop updating of the given method for reduction of the formation of toxic products of the reaction. Described method has good characteristics (the limit of the detection of this method 11 ug/l, CV &lt; 10 %, the coefficient of the correlation with reference method 0.99), the amount of toxic substances formed during reaction decreases in 3 times, the cost price of research is reduced owing to reduction of the volume of reagents and water.

Assessment of iodine intake in mildly iodine-deficient pregnant women by a new automated kinetic urinary iodine determination method

Maternal iodine deficiency can compromise the thyroid status of the mother, fetus and newborn child. Therefore, it is important to assess the iodine excretion level of groups of pregnant women. In this study we aimed to determine iodine intake in pregnancy using a recently reported automated kinetic method for urinary iodine determination. Urinary iodine measurements of 123 pregnant women (18 first, 28 second and 77 third trimester) were carried out using a new automated kinetic assay based on the Sandell-Kolthoff reaction at 37 degrees C and its kinetic measurement at 340 nm in a random-access automated analyzer after ammonium persulfate digestion at 95 degrees C in a water bath with +/-0.1 degree C precision. Statistical analyses were carried out using SPSS software. Whole group, first trimester, second trimester and third trimester urinary iodine concentrations (mean+/-SD) in pregnant women were 1.13+/-0.81, 1.08+/-0.71, 0.86+/-0.58 and 1.27+/-0.87 micromol/L, respectively. The urinary iodine concentration significantly increased with gestational age (p<0.05). We found that our study group was mildly iodine-deficient according to WHO criteria. Furthermore, the pregnant women were found to be mildly iodine-deficient in the first and third trimesters and moderately so in the second trimester. The only statistical difference was between second and third trimester values (p<0.05). Even though the increased iodine deficiency in the second trimester is not useful for early detection of iodine deficiency in pregnancy, the severity of this deficiency in the second trimester may lead to important effects on thyroid metabolism for both mother and fetus. Our study suggests that the iodine excretion of pregnant women living in iodine-deficient areas could be assessed using this fast and automated method.

Urinary iodine assays and ionophore based potentiometric iodide sensors

Urinary Iodine has been widely regarded as a biochemical marker for control of iodine deficiency disorders. Based on the Sandell-Kolthoff reaction, most colorimetric assay methods for urinary iodine (UI) determination that have been developed require pretreatment of urine sample. The non-Sandell-Kolthoff methods for UI assay provide alternative approaches for UI assay requiring only simple pretreatment or even without pretreatment. The selective ionophore-based iodide electrodes are highly applicable to the UI assay for large population due to their high selectivity and sensitivity to iodide, amenability to automation and ease of miniaturization. In this report, different assay methods are reviewed, including pretreatment procedures for Sandell-Kolthoff UI analysis. Finally, a summary of the state-of-the-art of the iodide ionophore-based ISEs that are suitable for UI assays are addressed.

Spectrophotometric determination of urinary iodine by the Sandell-Kolthoff reaction subsequent to dry alkaline ashing. Results from the Czech Republic in the period 1994–2002

The Czech Republic is an iodine-deficient area. Insufficient iodine intake was reduced by enriching cooking salt with iodine in the range 20-34 mg I/kg. An important indicator for tracking changes in iodine nutrition over time is accurate information about urinary iodine concentrations in the population. In this paper we describe and characterize our method used for the determination of iodine in biological material, which is based on alkaline ashing of urine specimens preceding Sandell-Kolthoff reaction using brucine as a colorimetric marker. The losses of radioiodine added during sample preparation have not exceeded 0.001%. The detection limit is 2.6 microg I/L and the limit of quantification is 11.7 microg I/L, with intra-assay precision of 4% and inter-assay precision of 4.9%. During the period 1994-2002, the urinary iodine concentration was determined in 29,612 samples in the Institute of Endocrinology. The mean basal urinary iodine concentrations+/-SD were 115+/-69 microg I/L. Of the samples, 0.7% were in severe (<20 microg I/L), 9.6% in moderate (20-49 microg I/L), 40.1% in mild (50-99 microg I/L), 35.6% in adequate (100-200 microg I/L), and 14.0% in more than adequate (>200 microg I/L) subsets of iodine nutrition. A statistically significant (p<0.00001) difference was found between mean male (127 microg I/L) and female (112 microg I/L) urinary iodine, and an inversely proportional trend also exists in the age-related data.