Scalp hair and serum iodine as potential biomarkers for iodine intake and their association with the thyroid function.

Aim: Iodine deficiency, which has adverse effects on health has re‐emerged in Australia. The present study aimed to develop and validate a novel iodine‐specific food frequency questionnaire for use in older Australians.Methods: A 49‐item food frequency questionnaire that included iodine‐rich foods was constructed and administered in 84 men and women aged 60–95 years with normal cognitive function. Dietary iodine intake assessed by the food frequency questionnaire was validated against three repeated 24‐hour dietary recalls. Urinary spot iodine concentrations were selected as iodine intake biomarker. Agreement between the two dietary methods was determined using a Bland–Altman plot and intra‐class coefficients. Correlations between dietary and urinary iodine were assessed. Forty‐three participants repeated the questionnaire after 9 months for reproducibility.Results: Mean iodine intake measured by the food frequency questionnaire and 24‐hour dietary recalls did not differ significantly (P= 0.870). The two methods were moderately correlated (r = 0.377;P< 0.05) and the Bland–Altman plots demonstrated an acceptable level of agreement (P= 0.870). Despite an association (r = 0.230;P< 0.05) between urinary iodine concentrations and 24‐hour dietary recalls, the food frequency questionnaire was not associated with urinary iodine concentration (r = 0.094;P= 0.40). The method of triads showed coefficients of 0.238 (urinary iodine), 0.953(food frequency questionnaire), 0.396 (24‐hour dietary recall) with the unknown true value.Conclusion: A short food frequency questionnaire to assess habitual dietary iodine intake in older Australians has been shown to be valid at the group level with regard to categorising individuals according to their habitual iodine intake. Reproducibility of the food frequency questionnaire remains to be demonstrated.

This study aims to evaluate the association of serum iodine concentration (SIC) with urinary iodine concentration (UIC) and thyroid function in pregnant women, as well as to provide the reference range of SIC of pregnant women in iodine-sufficiency area. Pregnant women were enrolled in the Department of Obstetrics, Tanggu Maternity Hospital, Tianjin from March 2016 to May 2017. Fasting venous blood and spot urine samples were collected. Serum free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), thyroglobulin (Tg), thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), UIC and SIC were measured. One thousand and ninety-nine participants were included in this study. The median UIC was 156μg/L. The median SIC was 108μg/L, and the 95% reference interval for SIC was 65.6-164.7μg/L. SIC was positively correlated with UIC (r=0.12, P<0.001), FT3 (r=0.23, P<0.001), and FT4 (r=0.50, P<0.001) and was inversely correlated with TSH (r=-0.14, P<0.001). Pregnant women with a SIC<79.9μg/L had a higher risk of hypothyroxinemia compared to those with higher SIC (OR=2.44, 95% CI: 1.31-4.75). Those having SIC>138.5μg/L were more likely to have thyrotoxicosis than those with lower SIC values (OR=13.52, 95% CI: 4.21-43.36). Serum iodine level is associated with UIC and thyroid function in pregnant women. Low SIC was associated with increased risk for iodine deficiency and hypothyroxinemia, while high SIC was related to excess and thyrotoxicosis.

Iodine: It's Important in Patients that Require Parenteral Nutrition

BackgroundBoth insufficient and excess iodine may produce thyroid disease. After salt iodization in China, the median urine iodine concentration (UIC) of children aged 8–10 years appeared adequate. However, it is unknown whether dietary changes due to rapid economic development in Shanghai have affected whole population iodine nutrition.ObjectiveTo assess dietary iodine intake, UIC and the prevalence of thyroid disease in the general population of Shanghai.DesignA cross-sectional survey was conducted with general participants aged 5–69 years (n = 7,904) plus pregnant and lactating women (n = 380 each) selected by stratified multistage sampling. The iodine concentrations in their salt, drinking water and urine were measured. Daily iodine intake was estimated using the total diet study approach. Serum thyroid hormone concentrations and thyroid-related antibodies were measured and thyroid ultrasonography was performed.ResultsThe median iodine concentration in salt was 29.5 mg/kg, and 12.8 µg/L in drinking water. Iodized salt, used by 95.3% of participants, contributed 63.5% of total dietary iodine. Estimated daily iodine intake was 225.96 µg. The median UIC of general participants was 146.7 µg/L; UIC <100 µg/L (iodine insufficiency) was seen in 28.6%; UIC >300 µg/L (iodine excess) in 10.1%. Pregnant women had a median UIC of 135.9 µg/L, with UIC <150 µg/L in 55.4%. Thyroid nodules and subclinical hypothyroidism were found in 27.44% and 9.17%, respectively.ConclusionsAccording to published criteria, the current dietary iodine intake in Shanghai was generally sufficient and safe, but insufficient in pregnant women. Thyroid nodules and subclinical hypothyroidism were the commonest thyroid diseases identified.

Whether iodized salt increases the risk of thyroid disease has been strongly debated in China, especially in the urban areas of coastal regions, in recent years. This study aimed to investigate the status of iodized salt in terms of urinary and serum iodine concentration in urban coastal areas, and to explore further whether consumption of iodized salt or non-iodized salt is associated with autoimmune thyroid disease (AITD). The data source was SPECT-China, a cross-sectional study in East China. A total of 1678 subjects were enrolled from 12 communities in downtown Shanghai. The type of salt consumed, the urinary iodine concentration (UIC), serum iodine, thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) levels were obtained. AITD was defined as serum TPOAb and/or TgAb >60 kIU/L (TPO/TgAb [+]). The prevalence of AITD was 10.5% in men and 21.4% in women. The median UIC and serum iodine concentration were 106.4 μg/L and 60.9 μg/L, respectively. Among all the subjects, 46.4% consumed non-iodized salt; the prevalence of iodine deficiency among those subjects was significantly higher than that of the subjects who consumed iodized salt (54.2% vs. 40.1%; p < 0.001). Consumption of non-iodized salt was positively associated with AITD in all participants (odds ratio [OR] = 1.49 [confidence interval (CI) 1.15-1.95]; p = 0.003) and in women (OR = 1.63 [CI 1.20-2.21]; p < 0.01) after multivariable adjustment. Additionally, the association between low UIC and AITD was observed among all subjects (OR = 1.50 [CI 1.10-2.05]; p = 0.01) and in women (OR = 1.45 [CI 1.02-2.07]; p = 0.038). In coastal areas, which are believed to be rich in iodine, consuming non-iodized salt still led to lower UIC levels and a higher prevalence of iodine deficiency. The consumption of non-iodized salt and low UICs might be a risk factor for AITD, especially for women, which should be further confirmed by longitudinal studies.

Dietary Iodine Intake in Urban and Rural North India: Implications for and Compatibility with Salt Reduction Efforts.

Japan is an iodine-replete country without iodine fortification. To characterize the current iodine status and thyroid function in healthy adults, a nationwide cross-sectional observational survey was conducted between 2016 and 2023. Iodine concentration in urine (UIC), serum and scalp hair as well as serum TSH, FT4 and FT3 concentrations, thyroid antibody (ThAb), thyroid volume by sonography, dietary iodine intake by diet study and anthropometry were evaluated. A total of 2,845 adults with the mean age of 45.6 years were recruited from 20 regions across Japan. The median UIC (mUIC) was 295.0 μg/L and within the WHO's adequacy range of iodine intake. There was a regional difference in indices of iodine status, thyroid function and prevalence of ThAb positivity throughout all of the regions. The mUIC was lowest in Tanegashima Island (169 μg/L) and highest in Fukui (943 μg/L). The highest median TSH (2.11 μIU/mL) with the lowest FT4 (1.22 ng/dL) was observed in Ishikawa, Hokuriku while the lowest TSH (1.06 μIU/mL) was in Rebun Island, Hokkaido although the median values of TSH, FT4 and FT3 were within their reference range. The prevalence of ThAb positivity was 12.6%. A significant positive correlation was observed only between mUIC and median TSH. Japanese adults consume more iodine than the average intake of other ethnic groups and there were some areas with high iodine intake. Current average iodine intake was estimated to be 400 μg per day in this study population. A large-scaled epidemiological survey is required in future.

National data on iodine status in Israel are lacking. Reliance on iodine-depleted desalinated water, the absence of a salt iodization program, and reports of increased use of thyroid medication in Israel suggest that the population's iodine intake is likely inadequate. The aims of this study were therefore to determine the iodine status of Israeli school-age children (SAC) and pregnant women (PW) in a nationally representative sample obtained by a novel approach of using pre-discard urinalysis samples collected from a centralized national laboratory. Spot urine samples from 1023 SAC and 1074 PW, representing all regions and major sectors in Israel, were collected during 2016 at the Maccabi Healthcare Services central laboratory. Urinary iodine concentration (UIC) was measured, and the results were analyzed by trimester, sex, region, and sector. SAC were iodine deficient, with a median (interquartile range [IQR]) UIC of 83 μg/L (52-127 μg/L); 62% of SAC UICs were below the World Health Organization adequacy range for SAC (100-199 μg/L). PW were also iodine deficient, with a median (IQR) UIC of 61 μg/L (36-97 μg/L); 85% of PW UICs were below the adequacy range for PW (150-249 μg/L). For both SAC and PW, the median UIC was below the World Health Organization's adequacy range across all sectors, sexes, and districts. Among SAC, the median (IQR) UIC was lower among females (75 μg/L; 48-119 μg/L) than males (92 μg/L; 59-133 μg/L; p < 0.05). Median UIC values of PW correlated significantly with the median UIC for SAC by sub-district (R2 = 0.3, p < 0.05). Urine sampling via a centralized national laboratory was efficient and cost-saving. Iodine deficiency in Israeli SAC and PW is a serious public-health concern. A national program of salt iodization and iodine supplementation of PW should be urgently considered.

An evaluation of urine and serum iodine status in the population of Tibet, China: No longer an iodine-deficient region.

Perinatal exposure to excess iodine can lead to transient hypothyroidism in the newborn. In Japan, large quantities of iodine-rich seaweed such as kombu (Laminaria japonica) are consumed. However, effects of iodine from food consumed during the perinatal period are unknown. The concentration of iodine in serum, urine, and breast milk in addition to thyrotropin (TSH), free thyroxine (FT(4)), and thyroglobulin was measured in 34 infants who were positive at congenital hypothyroidism screening. Based on the concentration of iodine in the urine, 15 infants were diagnosed with hyperthyrotropinemia caused by the excess ingestion of iodine by their mothers during their pregnancy. According to serum iodine concentrations, these infants were classified into group A (over 17 microg/dL) and group B (under 17 microg/dL) of serum iodine. During their pregnancies these mothers consumed kombu, other seaweeds, and instant kombu soups containing a high level of iodine. It was calculated that the mothers of group A infants ingested approximately 2300-3200 microg of iodine, and the mothers of group B infants approximately 820-1400 microg of iodine per day during their pregnancies. Twelve of 15 infants have required levo-thyroxine (LT(4)) because hypothyroxinemia or persistent hyperthyrotropinemia was present. In addition, consumption of iodine by the postnatal child and susceptibility to the inhibitory effect of iodine may contribute in part to the persistent hyperthyrotropinemia. We propose that hyperthyrotropinemia related to excessive iodine ingestion by the mother during pregnancy in some cases may not be transient.

To examine dietary iodine intake and urinary iodine concentration in young adults, as well as the relationship between iodine concentration in urine and muscle mass and speed of muscle reaction. Seventy euthyroid participants between the ages of 18 and 24 participated, 35 (50%) male and 35 (50%) female. The participants were young adults who live, study and work in the region of Osijek, Osijek-Baranja County, Croatia. Exclusion criteria were diagnosed thyroid disease and iodine metabolism disorder. Spot urine samples were analysed, dietary iodine intake was assessed, muscle mass and reaction speed were measured. The median concentration of iodine in urine was 120.77 &mu;g/L, and the estimated iodine intake was 624.66 &mu;g. The median muscle mass was 32.55%, and the median speed of muscle reaction 274.5 ms. A significant, negative and weak correlation between iodine concentration in urine and speed of muscle reaction was observed (Rho = -0.289). Other associations of urine iodine concentration and muscle mass percentage, muscle tissue and reaction speed were not significant Conclusion: The estimated dietary iodine intake was higher than the reference values of the World Health Organization. The urinary iodine concentration was within the reference values. Urinary iodine concentration was not related to muscle mass. Urinary iodine concentration in urine was significantly, negatively and weakly related to reaction speed.

Objective:Iodine is a trace element that synthesizes thyroid hormones necessary for optimal human growth and development. The relationship between dietary iodine intake and spot urinary iodine excretion in pregnant women has not been previously evaluated in Trabzon city, which is an endemic area of iodine deficiency in the Black Sea region of Turkey. This study aimed to evaluate the relationship between dietary iodine intake and urine iodine excretion in pregnant women.Materials and Methods:This study enrolled 150 pregnant women aged between 19 and 45 years who applied to Clinic of Gynecology and Obstetrics in Trabzon. Spot urine specimens were taken, and dietary iodine intake data were collected using a food frequency questionnaire (FFQ) and 24-hours dietary recall (24-h DR) method.Results:The median urinary iodine concentration (UIC) in the general specimen was 100.6 μg/L. Of the pregnant women, 80.0% had insufficient and 20.0% had sufficient iodine levels, according to UIC. Although total iodine-rich food intake determined by FFQ was sufficient in 20.7% (n=31) of participants, 24-h DR iodine intake was sufficient only 10.7% (n=16). A significant association between urinary iodine excretion and iodine intake was observed in both 24-h DR and FFQ intake estimates (p<0.05). The iodine intake values obtained in both 24-h DR and FFQ and the iodized salt effect were correlated with UIC in all models (p<0.05). Even though 96.0% of pregnant women used iodized salt, its effect on UIC was 15.2%.Conclusion:Both methods indicate that the iodine intake of pregnant women might be insufficient in Trabzon area. Also, although iodized salt use is high in pregnant women in Trabzon, it is not enough to prevent iodine deficiency.

To describe studies evaluating urinary iodine excretion during pregnancy and lactation in women living in cities with adequate or more than adequate iodine intake. Cross-sectional study conducted between 1996 and 1998 in pregnant women and a study of lactating women conducted in 2003. Pregnant women attending prenatal clinics in four cities in the Islamic Republic of Iran. Urinary iodine excretion and thyroid volume was measured in 403 women. In a second study, 100 lactating women from Taleghani Hospital in Gorgan, Iran were evaluated for thyroid size, and both urinary and breast milk iodine concentrations were determined. In Rasht city, 84% of pregnant women had a urinary iodine concentration of > or = 200 microg l-1, while in the other cities this percentage ranged from 45 to 55%. When data were combined for the cities of Ilam, Isfahan and Tehran, where women have an adequate or more than adequate median urinary iodine concentration, 51% of pregnant women had a urinary iodine concentration less than that recommended during pregnancy. In Rasht, where the median urinary iodine concentration indicates an excessive iodine intake, 15.4% of pregnant women had a urinary iodine concentration < 200 microg l-1. The mean urinary iodine concentration in lactating women was 250 microg l-1, and 16% of women had a urinary iodine concentration < 100 microg l-1. Grade 1 goitre was present in 8% of lactating women, and another 8% had grade 2 goitre. Findings of this study call for further attention to iodine intake during pregnancy and lactation. The currently recommended intake of iodine through universal salt iodisation may not be adequate for pregnant and lactating women, and supplementation during pregnancy and lactation should be further considered in light of the latest recommendations.

An epidemiologic study that evaluated population's iodine nutrition status and its relationship with thyroid hormones is lacking in iodine-sufficient area. This nationwide study aimed to evaluate the iodine nutrition status in Korea and relationship between urine iodine concentration (UIC) and thyroid hormones. A total of 8318 subjects of the Korea National Health and Nutrition Examination Survey VI (2013-2015) with UIC and thyroid hormone evaluation were included. Median UIC level and estimated 24-h iodine intake were calculated. The prevalence of iodine deficiency or excess was obtained using estimated average requirement or above the tolerable upper intake level cut-point method by estimated iodine intake. We analyzed UIC with regard to age, sex, social economic status, and geographic characteristics. The median UIC in general population and estimated iodine intake in adult population were 293.9μg/L (above requirement according to World Health Organization classification) and 249.3μg/day, respectively. The prevalence of iodine deficiency and excess was 14.0 and 13.4%. The median UIC was higher among SAC [511 (299.9-948.5)] and lower among seventies [251.2 (98.9-761.6)] compared to other age groups. The median UIC increased with household income level (p for trend < 0.001). The subjects living in rural and inland region had lowest UIC among the enrolled subjects. The subgroups with higher median UIC were associated with higher mean TSH levels. This first nationwide study in Korea demonstrated that the median of UIC and estimated iodine intake lie at nearly 300µg/L and 250µg/day, respectively, which shows an overall excellent iodine nutrition.

Background and Aim: In the present study, dietary iodine intake and thyroid functioning were assessed among the ethnic adolescent group of Eastern Himalayan range with the hypothesis that insufficient iodine intake negatively affects normal thyroid functions. The aim of the study was to see the prevalence and relation between iodine deficiency and thyroid functioning. Materials and Methods: It is a hospital-based study conducted in the health care facilities of Dima Hasao district, Assam, from April 2021 to March 2022. The study included 821 subjects including both male and female of adolescent age group (10–19 years). The thyroid profiling, anti-Thyroid peroxidase antibody (anti-TPO Ab), and urinary iodine content (UIC) were carried out. Thyroid hormone analysis was carried out by chemiluminescence assay. The anti-TPO Ab was determined using the electrochemiluminescence immunoassay analyzer. The dietary iodine intake was measured on the basis of UIC and was determined by arsenic cerium catalytic spectrophotometry method by the Sandell-Kolthoff reaction. Results: The prevalence of thyroid disorder among the studied population was found to be 13.8%. Among different conditions of thyroid disorders, hypothyroidism was present in 10.6% and hyperthyroidism in 3.13%. 4.18% had elevated anti-TPO Ab. Among the euthyroid subjects with different thyroid disorders, 1.48% and 21% had anti-TPO Ab positivity, respectively. The median UIC was 99.97 µg/l. 25.78% of the population had iodine deficiency. Thyroid disorders were common in subjects with iodine deficiency (61.34%) than iodine sufficient subjects (20%). Conclusion: The work was an attempt to demonstrate how the dietary iodine intake influences thyroid functioning among the adolescent ethnic population of Eastern Himalayas which is manifested as high prevalence of subclinical hypothyroidism with iodine deficiency. The work underscores region specific recommendation on iodine supplementation for populations living in geographically remote locations.