Urinary Iodine Excretion Values Research Articles

Current Iodine Status in Japan: A Cross-sectional Nationwide Survey of Schoolchildren, 2014-2019.

Japan has been regarded as a long-standing iodine-sufficient country without iodine fortification; however, data on nationwide iodine status are lacking. This study aimed to characterize the iodine status in Japan. From 2014 through 2019, a nationwide school-based survey was conducted across all districts in Japan. Urinary iodine concentration (UIC), creatinine (Cr) concentration, and anthropometry were assessed in healthy school-aged children (SAC) aged 6 to 12 years. Their iodine status is regarded as generally representative of the nation's iodine status. A total of 32 025 children participated. The overall median UIC was 269 μg/L, which was within the World Health Organization's adequacy range. There was a regional difference in UIC values within 14 regions, and the lowest and highest median UICs were found in Tanegashima Island (209 μg/L) and Nakashibetsu, Hokkaido (1071 μg/L), respectively. The median UIC ≥ 300 μg/L was observed in 12 of 46 regions. By using estimated 24-hour urinary iodine excretion (UIE), the prevalence of SAC exceeding the upper tolerable limit of iodine for Japanese children was from 5.2% to 13.7%. The UIC values did not change with age, body surface area and body mass index percentile, whereas the Cr concentration simultaneously increased suggesting the effect of urinary creatinine on UI/Cr and estimated 24-hour UIE values. The iodine intake of Japanese people is adequate, but in some areas it is excessive. The incidence and prevalence of thyroid disorders associated with iodine intake should be obtained, especially in the areas where high amounts of iodine are consumed.

Use of Salivary Iodine Concentrations to Estimate the Iodine Status of Adults in Clinical Practice

BackgroundMeasurement of the 24-h urinary iodine concentration or urinary iodine excretion (UIE) is the gold standard to determine iodine status; however, this method is inconvenient. The use of salivary iodine could be a possible alternative since salivary glands express the sodium-iodine symporter. ObjectivesWe aimed to establish the correlation between the salivary iodine secretion and UIE, to evaluate the clinical applicability of the iodine saliva measurement. MethodsWe collected 24-h urine and saliva samples from 40 participants ≥18 y: 20 healthy volunteers with no specific diet (group 1), 10 patients with differentiated thyroid cancer with a low dietary intake (<50 μg/d, group 2), and 10 patients with a high iodine status as the result of the use of amiodarone (group 3). Urinary and salivary iodine were measured using a validated inductively coupled plasma MS method. To correct for differences in water content, the salivary iodine concentration (SIC) was corrected for salivary protein and urea concentrations (SI/SP and SI/SU, respectively). The intra- and inter-individual CVs were calculated, and the Kruskal-Wallis test and Spearman's correlation were used. ResultsThe intra-individual CVs for SIC, SI/SP, and SI/SU were 63.8%, 37.7%, and 26.9%, respectively. The inter-individual CVs for SIC, SI/SP, and SI/SU were 77.5%, 41.6% and 47.0%, respectively. We found significant differences (P < 0.01) in urinary and salivary iodine concentrations between all groups [the 24-h UIE values were 176 μg/d (IQR, 96.1–213 μg/d), 26.0 μg/d (IQR, 22.0–37.0 μg/d), and 10.0*103 μg/d (IQR, 7.57*103–11.4*103 μg/d) in groups 1–3, respectively; the SIC values were 136 μg/L (IQR, 86.3–308 μg/L), 71.5 μg/L (IQR, 29.5–94.5 μg/L), and 14.3*103 μg/L (IQR, 10.6*103–25.6*103 μg/L) in groups 1–3, respectively]. Correlations between the 24-h UIE and SIC, SI/SP, and SI/SU values were strong (ρ = 0.80, ρ = 0.90, and ρ = 0.86, respectively; P < 0.01). ConclusionsStrong correlations were found between salivary and urinary iodine in adults with different daily iodine intakes. A salivary iodine measurement can be performed to assess the total iodine body pool, with the recommendation to correct for salivary protein or urea.

Urinary iodine excretion and thyroid function status in school age children of hilly and plain regions of Eastern Nepal.

BackgroundIodine deficiency is a major public health problem in many developing countries including Nepal. The present study was designed to investigate the urinary iodine excretion (UIE), thyroid function status and household salt iodine content (SIC) in school-aged children (SAC) and to establish the relationships between these factors.MethodsA community-based cross sectional study was conducted in selected schools of two districts, Tehrathum and Morang, lying in the hill and plain region of eastern Nepal respectively. A total of 640 SAC, (Tehrathum n = 274 and Morang n = 366) aged 6–11 years, were assessed for UIE and household SIC. Among the 640 children, 155 consented to blood samples (Tehrathum n = 78 and Morang n = 77) to test for serum thyroglobulin (Tg), thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4). UIE was measured by ammonium persulfate digestion method. SIC was measured by iodometric titration method and Tg, TSH, fT4 and fT3 were measured by immunoassay based kit method.ResultsIn Tehrathum and Morang, 9.5 and 7.7 % of SAC had UIE values of UIE <100 µg/L while 59.5 and 41 % had iodine nutrition values of >299 µg/L, with median UIE of 345.65 and 270.36 µg/L respectively. The overall medians were as follows, Tg 14.29 µg/L, fT3 3.94 pmol/L, fT4 16.25 pmol/L and TSH 3.61 mIU/L. There was a negative correlation between UIE and Tg (r = −0.236, p = 0.003) and a positive correlation between UIE and SIC (r = 0.349, p < 0.0001). We found 19.5 %, n = 15 and 16.7 %, n = 13 subclinical hypothyroid cases in Morang and Tehrathum respectively. Iodometric titration showed only 6.4% (n = 41) of the samples had household SIC <15 ppm. Multivariate analysis revealed that use of packaged salt by SAC of Tehrathum district correlated with higher UIE values.ConclusionsOur focused data suggests that collaborative universal salt iodization (USI) programs are improving the health of children in the Tehrathum and Morang districts of Nepal. We also found that excessive iodine in a large portion of the study groups is a substantial concern and iodine intervention programs need to deal with both deficient and excessive iodine scenarios that can both be present simultaneously in study populations.

Excessive iodine intake in schoolchildren

Inadequate iodine intake may result in iodine deficiency disorders (IDD). Thus, for more than 50 years, policies for the regulation of salt fortification with iodine have existed in Brazil. In 2003, a study on 6-14-year-old schoolchildren from regions of the state of São Paulo showed a median urinary iodine concentration of 360 μg/L. The objective of the present study was to assess the iodine nutrition status among schoolchildren. The study was conducted on 828 schoolchildren aged 4-13 years from eight schools in the interior of the state of São Paulo. A casual urine sample was collected from each volunteer for iodine determination by the adapted method of Sandell-Kalthoff. Only 1.9% (n = 16) of the children evaluated had low values of urinary iodine (<100 μg/L), while 24.6% had urinary iodine excretion values between 200 and 300 μg/L, and 67.1% had values above >300 μg/L. The results show that the iodine nutritional status of the schoolchildren studied is characterized by a high urinary iodine excretion, which might reveal an increase in iodine consumption by this population.

A review of tracking progress towards elimination of Iodine deficiency disorders in Tamil Nadu, India

Iodine deficiency disorders (IDD) are significant health problem in India. But there is dearth of regional/state level information for the same. This study was designed to study the current status of IDD in Tamil Nadu. A cross-sectional community-based survey was conducted in the state of Tamil Nadu. The study population was children in the age group of 6-12 years and the probability proportional to size 30 cluster methodology was used for sample selection. The parameters studied were prevalence of goiter, urinary iodine excretion, and iodine content in salt at the household level. A total of 1230 children aged between 6 and 12 years were studied. The total goiter rate was 13.5% (95% CI: 11.1-14.9). The median urinary iodine excretion was found to be 89.5 μg/L (range, 10.2-378 μg/L). The 56% of the urinary iodine excretion values were <100 μg/L. The proportion of households consuming adequately iodized salt (iodine content ≥ 15 parts per million) was 18.2% (95% CI: 16.1-20.5). The total goiter rate of 13.5% and median urinary iodine excretion of 89.5 μg/L is indicative of iodine deficiency in Tamil Nadu.

The Republic of Srpska Iodine Deficiency Survey 2006

A survey related to iodine deficiency in the Republic of Srpska was first conducted in 1999 and resulted in the adoption of regulations concerning the quality of salt for human consumption. In order to reassess iodine status, we conducted the Republic of Srpska Iodine Deficiency Survey in 2006. The survey was conducted in a sample of 1,200 schoolchildren using parameters recommended by WHO, UNICEF and ICCIDD: palpation of thyroid gland, iodine urinary excretion, thyroid utrasonography and content of iodine in salt. The goiter prevalence in the total group indicated mild iodine deficiency in the Republic of Srpska, whereas urinary iodine excretion suggested iodine sufficiency. Only 35.7% of salt samples were adequately iodinated, 51.2% were hypo-iodinated and 13.1% were hyper-iodinated. Of the salt samples tested, 40.9% were iodinated using potassium iodide, despite the fact that this method of salt iodination is forbidden by regulations related to the quality of salt for human consumption. Higher prevalence of goiter and lower urinary iodine content was found in rural areas compared to urban ones, although the iodine content of salt did not differ between these two areas. It seems that the Republic of Srpska has progressed from moderate (1999) to mild iodine deficiency with a wide range in the urinary iodine excretion values. However, the salt for human consumption is of low quality. The higher prevalence of goiter and the lower urinary iodine values in rural areas compared to urban ones may be attributed to differences in salt usage and/or nutritional factors.

Iodine status among pregnant women in Kuwait

Up to now, little has been known about iodine intake and the prevalence of iodine deficiency (ID), if any, in Kuwait. Urinary iodine excretion (UIE) and changes in thyroid function during pregnancy were thus evaluated. Urinary iodide level was measured in random urine samples collected from 326 pregnant women at different gestational trimesters. Blood samples were drawn for free T4 (FT4) and TSH level determination. Median UIE levels fall within the normal range during all gestational trimesters i.e. >100 microg/l. However, if the new suggested recommendation for pregnant women <140 microg/l, is applied, median UIE values during trimesters 2 and 3 indicate ID. Mean serum TSH levels increased between trimesters 1 and 3 (p<0.05), whereas serum FT4 decreased between first and second trimesters (p<0.05), and this reduction continued at the third trimester. Furthermore, an increase in TSH levels for subjects with mild and moderate ID (Mi and Mo, respectively) were noticed (p<0.05) during the second trimester. However, FT4 levels dropped in subjects with Mi and Mo ID during the first trimester (p<0.05). In conclusion, these results suggest that 56.8% of pregnant women had median UIE level <145 microg/l, associated with high TSH and low FT4 levels. Data obtained may indicate insufficient iodine intake among pregnant women in Kuwait.

Prevalence of Goiter in Children 6 to 12 Years of Age in Ethiopia

Iodine-deficiency disorders are a major public health problem in Ethiopia. In conjunction with implementing control programs, baseline information needs to be established. To investigate the distribution and degree of severity of iodine-deficiency disorders in terms of goiter prevalence, urinary iodine excretion (UIE) levels, and proportion of households with iodated salt in Ethiopia. A nationwide, community-based, cross-sectional study was conducted from February to May 2005 among 10,965 children aged 6 to 12 years. A multistage, proportional-to-population-size sampling method was used. Goiters were classified by the method recommended by the World Health Organization/UNICEF/International Council for the Control of Iodine Deficiency Disorders (WHO/UNICEF/ICCIDD), in which the thyroid gland is graded as 0 (normal), 1 (palpable goiter), or 2 (visible goiter); urinary iodine was determined by the wet digestion method; and salt samples were analyzed by a rapid test kit. The national total goiter weighted prevalence rate among children aged 6 to 12 years was 39.9% (95% confidence interval, 38.6% to 41.2%), representing more than 4 million children. The median UIE was 2.45 microg/ dL; 45.8% of children had UIE values of 2 microg/dL or less, and 22.8% had UIE values of 2.01 to 5.0 pg/dL. Only 4.2% of the households had iodated salt. According to the WHO/UNICEF/ ICCIDD classification, both goiter prevalence and UIE levels indicate that the whole country appears to be severely affected by iodine deficiency. Furthermore, the virtual absence of iodated salt in the households shows that currently there is no salt iodization program in the country. Dietary sources of iodine in Ethiopia are not dependable, and hence a sustainable universal salt iodization program needs to be implemented without delay.

A challenge for monitoring iodine deficiency disorders in rural Nepal

Developing a strategy for monitoring iodine deficiency disorders (IDD) remains a big challenge in rural Nepal where great variations could exist in IDD status. To explore the possibility of variation in urinary iodine excretion (UIE) level in rural settings, we carried out a detailed study of UIE among 586 school children of 20 schools in five villages. Our data revealed statisitically significant differences in UIE values among rural villages and schools in the same villages. The policy-makers should keep such variations in mind for a successful monitoring of IDD in Nepal and other countries where such variations may exist.

Situación nutricional de yodo en la población escolar de Alicante

According to the World Health Organization (WHO), goiter is endemic in Spain. The main cause of endemic goiter is iodine deficiency, which is also the principal cause of mental retardation and avoidable cerebral palsy throughout the world. We conducted an observational study to determine the prevalence of endemic goiter and nutritional iodine status in the province of Alicante. Urinary iodine excretion was measured in a morning urine sample, and thyroid volume was measured by means of a thyroid ultrasound scan. A case of goiter was diagnosed if thyroid volume was above the 97th percentile adjusted by age, as published by the WHO. No cases of goiter were found. In addition, the median urinary iodine excretion levels adjusted by age were within the normal range, as defined by the WHO's criteria. Endemic goiter was not found in the province of Alicante and urinary iodine excretion values demonstrated adequate iodine intake. Further ultrasound studies are needed to establish reference thyroid volumes for our population.

Iodine intake in pregnancy in Ireland — A cause for concern?

Adequate dietary iodine intake is necessary to maintain maternal thyroid function at a level permitting normal neuropsychological development of the foetus. To determine dietary iodine status by measuring urinary iodine excretion (UIE), proportional to dietary intake, in Irish mothers during the first trimester of pregnancy. Median UIE showed seasonal variations, being lower in summer than in winter. The median values in pregnant women were, summer 45microg/l, winter 68microg/l. Equivalent values for controls were 43 and 91microg/l respectively. UIE required to achieve WHO recommended daily iodine intakes would be 120-180microg/l. In the Irish subjects UIE values suggestive of iodine deficiency (<50microg/l) were observed in 55% of pregnant women tested in summer and 23% in winter. Dairy milk iodine, a major dietary iodine source, showed similar variation. While there is as yet no available evidence of widespread thyroid hypofunction in the Irish obstetric population, the findings are a cause of concern, which if confirmed by a more comprehensive investigation, may indicate the need for iodine prophylaxis.

Diagnostic 123I and 131I activities and radioiodine therapy

Urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated effects of the application of different radioiodine isotopes on UIE in patients with differentiated thyroid carcinoma (DTC). In 91 consecutive patients with DTC UIE, measured as iodine/creatinine ratio, was determined before and after application of 123I and 131I for diagnostic or therapeutic purposes. Additionally, remnant volume (V) was determined prior to therapy. Group A consisted of 33 patients with supposed successful ablation of DTC. These patients received 370 MBq 131I for diagnostic use and served as controls. 58 patients (group B) with remnants, relapses and metastases received 370 MBq 123I for diagnostics prior to therapy with 1.5-22.2 GBq 131I. Factors influencing individual changes in urinary iodine excretion (deltaUIE) were investigated by using non-parametric tests. In group A UIE did not change significantly after application of 131I. As well, UIE remained unchanged after diagnostic application of 123I in group B. In contrast, UIE increased significantly already 24 h after therapeutic application of 131I in this group. In patients with small remnants (V < 2.5 ml) a significant but only moderate increase of UIE could be observed (average increase: 47 microg I/g crea). In patients with larger remnants, with relapses or metastases increase of UIE values was significant and more pronounced. It was confirmed that UIE increased significantly during radioiodine therapy in patients with DTC and radioiodine-accumulating tissue. The increase of UIE after therapeutic administration of radioiodine can be explained by the disintegrated thyroid follicles in thyroid remnants. The radioiodine-induced iodine release may be one reason for thyroid "stunning" even after application of diagnostic amounts of 131I.

Iodine deficiency in Calabria: characterization of endemic goiter and analysis of different indicators of iodine status region-wide.

The distribution of goiter prevalence in schoolchildren (no.=13,984, age 6-14 yr), the neonatal TSH results obtained from the congenital hypothyroidism screening program and the urinary iodine excretion values (no.=284) were employed for the assessment of iodine deficiency in Calabria, a Southern Italy region. Data were collected during the years 1990-1996. In the inland territory, goiter prevalence ranged from 19 to 64%. At sea level, there was a great variability of goiter prevalence, with values varying from 5.3 to 25.7%. The analysis of the neonatal hypothyroidism screening program data (no.=21,078) showed a 14.8% frequency of TSH levels >5 microU/ml whole blood in newborns from the inland territory and a 14.1% frequency at sea level. Urinary iodine excretion resulted (mean+/-SD) 53.8+/-43.4 microg/l (range: <20 to 189 microg/l) in the inland territory and 89.6+/-59.8 microg/l (range: 26 to 333 microg/l) at sea level. Median urinary iodine excretion values in 13 villages or small towns of the inland territory ranged from 31 to 57 microg/l. In 2 major towns located at sea level, the median iodine excretion values were 72 microg/l in Crotone main city and 94 microg/l in Reggio Calabria main city. The data indicated that moderate, with pockets of severe iodine deficiency is present in the inland region while iodine supply varies from sufficient to marginally low in the coastal areas. Mild iodine deficiency was found in a major town located at sea level.

The epidemiology of iodine deficiency disorders (IDD) in Yemen.

This first nationwide survey was undertaken to estimate the prevalence rates and severity of iodine deficiency disorders (IDD) and the proportion of households consuming iodized salt. The country was stratified into two ecological zones and 30 clusters (primary schools) from each zone, including the required numbers of pupils, were selected randomly. A subsample of pupils provided urine and salt samples for the determination of urinary iodine excretion (UIE) and presence of iodate, respectively. Yemen. There were a total of 2984 pupils aged 6-12 years of whom 2003 were boys and 981 girls. The majority (1800) pupils were from the lowland/coastal areas (zone II) and the rest (1184) from the mountainous regions (zone I). The total goitre rates (TGR) in the whole country, zones II and I were 16.8%, 31.1% and 7.4%, respectively. The TGR in zone I for males was 32.8% and 27.3% for females, while in zone II the corresponding rates were 8.1% and 5.9%, respectively, and the differences were not statistically significant. Only three cases of visible goitres were encountered. The median UIE levels in zones I, II and the whole country were 13.6, 18.9 and 17.3 microg dl-1, respectively. Based on UIE cut-off points recommended by WHO, IDD was severe in 4.7% of pupils in zone I and 2.6% in zone II. Mild and moderate IDD were found in 18.5% and 8.7% of the pupils respectively. Nearly 70% of the surveyed pupils had UIE values of >/= 10 microg dl-1 (no deficiency). Girls had relatively better iodine nutrition as suggested by higher levels of median UIE. In addition, across all age groups median UIE values were above 10 microg dl-1. Over half of the households consumed iodized salt. Since the introduction of universal salt iodization in 1996 both the prevalence and severity of IDD in Yemen were reduced markedly and Yemen can now be classified as a country with a mild IDD problem. However, the low level of households consuming iodized salt may hamper the goal of IDD elimination.

Low levels of urinary iodine excretion in schoolchildren of rural areas in Cuba.

We set up a baseline data on urinary iodine excretion from a nationwide representative sample of rural schoolchildren before instituting iodine supplementation. Stratified multistage cluster sampling in three different strata: lowlands, foothills and mountainous areas. Early morning urine samples were collected for evaluation of iodine status. Field study in 25 municipalities in 11 out of 14 provinces. The study was carried out from October to December 1995. Three thousand and twenty-seven schoolchildren of either sex, 6 to < 12 y from 87 primary schools. The median urinary iodine excretion was 95 microg/L for the whole sample. The situation in a few foothills and all mountainous areas showed a moderate to severe deficiency. In the mountainous stratum, the median urinary iodine excretion values was less than 20 microg/L. Cuba has a mild iodine deficiency public health problem with respect to WHO criteria, which in the mountainous areas is severe. The Government of Cuba has started a national Plan of Action and funds are being mobilized to introduce nationwide iodized salt.

Autoimmune thyroid disease in the puerperium. Predictive value of thyroid enlargement and related hormonal changes occurring during pregnancy

The incidence of goiter detected during pregnancy and its significance as an indicator of autoimmune thyroid disease after delivery was investigated in a sample of 707 pregnant women (81% in their 2nd trimester of gestation). Goiter was detected in 106 subjects (15%). Blood T4, T3, TSH, free T4 index (FT4I), antimicrosomal antibodies (AMA) and urinary iodine excretion were measured in these women and in a control group of gravidas without goiter. These measurements were repeated at 1 and 3 months after delivery. Compared with controls during pregnancy, subjects with goiter had lower FT4I values (11.0 +/- 2.8 vs 9.0 +/- 1.8; p less than 0.01) and higher TSH values (2.9 +/- 0.6 microU/ml vs 4.2 +/- 2.1 microU/ml; p less than 0.01). In contrast, T4, T3, AMA and urinary iodine excretion values were similar in both groups. In subjects with goiter FT4I values increased over pregnancy levels at 1 month (11.2 +/- 2.0; p less than 0.05) and 3 months (14.0 +/- 3.0; p less than 0.05) after delivery; in 29% a biochemical hyperthyroidism (FT4I greater than 13.5) was detected. During the same period TSH values decreased significantly (1 month: 1.9 +/- 0.7 microU/ml; p less than 0.05; 3 months: 2.7 +/- 3.0 microU/ml; p less than 0.05). Frequency of positive AMA increased from 8.6% during pregnancy up to 32.1% in the post-delivery period (p less than 0.01). In the control group no variation in the FT4I, TSH or AMA were observed after delivery. These results indicate that goiter during pregnancy is common in Chilean gravidas and that it has predictive value for the appearance of autoimmune thyroid disease after delivery.

Findings relating to goiter and iodine in the Ten-State Nutrition Survey

Examinations for thyroid size were carried out on 35,999 individuals in the Ten-State Nutrition Survey. Overall goiter prevalence was found to be 3.1 per cent with the higher prevalence of goiter among adolescents and adults. Females of all ages had a higher prevalence of goiter than did males. No consistent regional pattern of the occurrence of goiter was observed. Urinary iodine excretion values used to estimate iodine intake indicated very few persons with excretion values suggesting iodine deficiency. No association between goiter and low iodine excretion was observed. On the contrary, a higher prevalence of goiter was found among persons excreting high levels of iodine. There is no indication from this study of widespread, iodine-deficiency goiter.

Endemic goiter in Greece: metabolic studies.

Iodine metabolism studies were performed in goitrous and nongoitrous inhabitants of the endemic areas of Central Greece. All the groups investigated showed an iodine-deficiency pattern, characterized by low plasma inorganic iodine (PII) and urinary iodine excretion values, high radioiodine uptake and clearance rates, but normal values for the absolute iodine uptake and PBI. There was a tendency for the goitrous to have a higher radioiodine uptake, and in one village a lower PII level. The PBI values, although generally normal, had a mean value slightly below that of the controls from a nonendemic area, and the difference was significant for the male group. The intrathyroidal exchangeable iodine pool was reduced in the goitrous persons. The excretion of urinary iodine was more severely reduced in the females. There was no difference in the renal iodide clearance between goitrous and nongoitrous persons. The butanol-insoluble iodine was higher in the goitrous than in the controls from a nonendemic area, wit...