scholarly journals Study on the relationship of iodine nutritional status with thyroid function and autoantibodies in pregnant women in Baotou

2020 ◽  
Vol 7 (1) ◽  
pp. 3
Author(s):  
Yuanyuan Fan ◽  
Yalu Wang ◽  
Chenhui Li ◽  
Ziling Li
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Thyroid Peroxidase ◽  
Urinary Iodine Concentration ◽  
Iodine Excess ◽  
The Difference ◽  
Relationship Of

Objective: To investigate the relationship of iodine nutritional status with thyroid function in pregnant women in Baotou, and provide a scientific basis for the guide of reasonable iodine supplementation.Methods: By use of As-Ce catalysis spectrophotometry, the urinary iodine concentration was determined in 90 women during different periods of pregnancy admitted to Baogang Hospital of Inner Mongolia from January 2017 to December 2017. The determination of thyroid function and the autoantibody level was carried out by electro-chemiluminescence immunoassay (ECLIA).Results: In the early trimester of pregnancy, pregnant women with iodine deficiency, iodine sufficiency and iodine excess accounted for 36.67%, 40.00% and 23.33% respectively; in the middle trimester of pregnancy, they accounted for 66.67%, 26.67% and 6.66% respectively; they made up 40.00%, 40.00% and 20.00% respectively in the late trimester of pregnancy. The rate of iodine deficiency in women in the middle trimester of pregnancy was significantly higher than that in women in the early and the late trimesters of pregnancy respectively, and the difference was statistically significant (p < .05). The rate of iodine deficiency in pregnant women was positively correlated to the positivity of thyroid peroxidase antibody. Moreover, it had no relationship with the positivity of thyroglobulin antibody. No matter in the pregnant women with iodine deficiency or with iodine excess, the abnormality rate of thyroid function and autoantibodies was significantly higher than that in the pregnant women with iodine sufficiency. The difference was statistically significant (p < .05).Conclusions: The iodine deficiency in the women in the middle trimester of pregnancy is more severe than that in the women in the early and the late trimesters of pregnancy. Iodine deficiency during pregnancy is positively correlated with the positivity of thyroid peroxidase antibody. Pregnant women with iodine deficiency and iodine excess show a higher abnormality rate of thyroid function and autoantibodies. It is recommended to advocate health education on iodine nutrition to pregnant women, and conduct the dynamic monitoring of urinary iodine concentration and the screening of thyroid function and autoantibodies during pregnancy.

scholarly journals Adequately iodized salt is an important strategy to prevent iodine insufficiency in pregnant women living in Central Java, Indonesia

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242575
Author(s):  
Ina Kusrini ◽  
Jessica Farebrother ◽  
Donny Kristanto Mulyantoro
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Interquartile Range ◽  
Iodized Salt ◽  
Vulnerable Groups ◽  
Urinary Iodine Excretion ◽  
Urinary Iodine Concentration

Iodine is an essential micronutrient for cognitive development and growth. Optimal intakes are critical during pregnancy. We report the iodine status and thyroid function of pregnant women living in areas previously affected by severe iodine deficiency and in longstanding iodine sufficient areas in Java, Indonesia. This cross-sectional study was conducted in Magelang, Java, from July to November 2015, in four sub-districts; two previously affected by severe iodine deficiency (area 1) and two that were iodine-sufficient (area 2). Iodine intake was estimated using median urinary iodine concentration in spot samples and mean urinary iodine excretion in 3 x 24-hour samples, thyroid hormones (thyroid-stimulating hormone and free thyroxine) were measured in venous blood samples, and iodine content of household salt samples was estimated by titration. We recruited a total of 244 pregnant women, 123 in area 1 and 121 in area 2. Urinary iodine results suggested adequate habitual iodine intakes in both areas (median urinary iodine concentration in area 1: 222 μg/l (interquartile range 189, 276 μg/l), area 2: 264 μg/l (interquartile range 172, 284 μg/l), however, the risk of inadequate intakes increased with advancing trimester (Odds Ratio = 2.59 (95% CI 1.19–5.67) and 3.85 (95% CI 1.64–9.02) at second and third trimesters, respectively). Estimated prevalence of thyroid function disorders was generally low. Salt was iodized to approximately 40 ppm and foods rich in native iodine did not contribute significantly to dietary intakes. Adequately iodized salt continues to prevent iodine insufficiency in pregnant women living in areas previously affected by severe iodine deficiency in Java, Indonesia. Monitoring and surveillance, particularly in vulnerable groups, should be emphasized to ensure iodine sufficiency prevails.

scholarly journals Mild to moderate iodine deficiency in pregnancy: A matter of debate

2021 ◽  
Vol 5 (1) ◽  
pp. 018-026
Author(s):  
Delshad Hossein ◽  
Azizi Fereidoun
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Urinary Iodine Concentration ◽  
Iodine Nutrition ◽  
Iodine Supplementation ◽  
Iodine Deficiency In Pregnancy ◽  
In Pregnancy

During the last few decades painstaking efforts have been made to eliminate iodine deficiency through the world. Nowadays in regions where dietary iodine intake is adequate or borderline, the main focus is increasing dietary iodine supply in the target population during pregnancy and the first years of life. Severe iodine deficiency during pregnancy increases the risk of irreversible brain damage, intellectual disability, neurologic abnormalities, stunted growth, increased pregnancy loss, infant mortality, impairments in child development and cretinism. The potential effects of mild-to-moderate iodine deficiency are debated. Results from animal studies and observational human studies indicate that maternal mild-to-moderate iodine deficiency disturbs thyroid function in pregnancy and it also may affects fetal neurodevelopment. The effect of supplementation of iodine on thyroid function of pregnant women and their newborn, neurodevelopment of infants and cognitive performance of children have been investigated using iodine nutrition in pregnancy, based on median urinary iodine concentration. However they have found conflicting results regarding the benefits or harms of iodine supplementation in pregnancy. Although many epidemiological, interventional and clinical studies have supported the association between thyroid function in pregnant women and later psychomotor and mental development of their children, the effect of iodine supplementation in pregnant women on neurodevelopment of children is inconclusive. Even in areas with well-established universal salt iodization program, pregnancy could be at risk of having iodine deficiency and despite WHO/ICCIDD/UNICEF recommendation which believe that dietary iodine fortification during pregnancy depends primarily on the extent of pre-existing iodine deprivation, systematic dietary fortification needs to be implemented in this vulnerable group. However, iodine supplementation of mildly iodine deficient pregnant women may not have beneficial effects in their thyroid function or neurodevelopment of their children.

scholarly journals Evaluation of median urinary iodine concentration cut-off for defining iodine deficiency in pregnant women after a long term USI in China

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Huidi Zhang ◽  
Meng Wu ◽  
Lichen Yang ◽  
Jinghuan Wu ◽  
Yichun Hu ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Iodine Intake ◽  
Urinary Iodine Concentration ◽  
Normal Thyroid ◽  
Normal Thyroid Function

Abstract Background The WHO/UNICEF/ICCIDD define iodine deficiency during pregnancy as median urinary iodine concentration (MUIC) ≤ 150 μg/L. China implemented universal salt iodization (USI) in 1995, and recent surveillance showed nationwide elimination of iodine deficiency disorders (IDD). Data from 2014 showed that the MUIC in 19,500 pregnant women was 154.6 μg/L and 145 μg/L in 9000 pregnant women in 2015. However, symptoms of iodine deficiency were absent. Our study sought to evaluate whether MUIC below 150 μg/L affects thyroid function of Chinese pregnant women and their newborns in Chinese context. Methods We screened 103 women with normal thyroid function and MUIC lower than 150 μg/L during week 6 of pregnancy at Peking Union Medical College Hospital. Patient demographics and dietary salt intake were recorded. Subjects were followed at 12, 24, and 32 gestational weeks. At each visit, a 3-day dietary record, drinking water samples, and edible salt samples were collected and analyzed for total dietary iodine intake. Additionally, 24-h urine iodine and creatinine were measured. Blood tests assessed thyroid function in both mothers and newborns. Results Of 103 pregnant women enrolled, 79 completed all follow-up visits. Most subjects maintained normal thyroid function throughout pregnancy. However, 19 had thyroid dysfunction based on thyroid stimulating hormone and free thyroxine levels. The median serum iodine was 71 μg/L (95% CI: 44, 109). The median thyroglobulin was < 13 μg/L. values above this level indicate iodine deficiency in pregnant women. The median dietary iodine intake during pregnancy, derived from the 3-day record and measures of water and salt, was 231.17 μg/d. Assuming 90% urinary iodine excretion (UIE), 200.11 μg/d UIE means the 222.34 μg iodine loss per day, suggesting that subjects had a positive iodine balance throughout pregnancy. All neonatal blood samples showed TSH levels lower than 10 mIU/L, indicating normal thyroid function. No significant difference was found among gestational weeks for urinary iodine, and the MUIC in subjects who completed 3 follow-up visits was 107.41 μg/L. Conclusion Twenty years after implementing USI, expectant Chinese mothers with MUIC of 107.4 μg/L, less than the WHO’s 150 μg/L benchmark, maintained thyroid function in both themselves and their newborn babies.

scholarly journals High Iodine Deficiency among Pregnant Women in Periurban Ghana: A Hospital-Based Longitudinal Study

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
David Larbi Simpong ◽  
Yaw Asante Awuku ◽  
Kenneth Kwame Kye-Amoah ◽  
Martin Tangnaa Morna ◽  
Prince Adoba ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Pregnant Women ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Clinical Information ◽  
Iodine Concentration ◽  
Iodized Salt ◽  
Urinary Iodine Concentration ◽  
Study Cohort ◽  
Iodine Sufficiency

Background. Iodine deficiency causes maternal hypothyroidism which can lead to growth, cognitive, and psychomotor deficit in neonates, infants, and children. This study examined the iodine status of pregnant women in a periurban setting in Ghana. Methods. This longitudinal study recruited 125 pregnant women by purposeful convenience sampling from the antenatal clinic of the Sefwi Wiawso municipal hospital in Ghana. Urinary iodine concentration (UIC) was estimated by the ammonium persulfate method at an estimated gestational age (EGA) of 11, 20, and 32 weeks. Demographic information, iodized salt usage, and other clinical information were collected using a questionnaire. Results. The prevalence of iodine deficiency among the pregnant women was 47.2% at EGA 11 and 60.8% at both EGA of 20 and 32, whereas only 0.8% of participants not using iodized salt had iodine sufficiency at EGA 32. 18.4%, 20%, and 24% of participants using iodized salt had iodine sufficiency at EGA 11, 20, and 32, respectively. Conclusion. A high prevalence of iodine deficiency was observed among our study cohort.

scholarly journals Iodine Intake and Thyroid Function in Pregnant Women in a Private Clinical Practice in Northwestern Sydney before Mandatory Fortification of Bread with Iodised Salt

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Norman Blumenthal ◽  
Karen Byth ◽  
Creswell J. Eastman
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Blood Collection ◽  
Antenatal Visit ◽  
Urinary Iodine Concentration ◽  
Cross Sectional

Aim. The primary objective of the study was to assess the iodine nutritional status, and its effect on thyroid function, of pregnant women in a private obstetrical practice in Sydney.Methods. It was a cross-sectional study undertaken between November 2007 and March 2009. Blood samples were taken from 367 women at their first antenatal visit between 7 and 11 weeks gestation for measurement of thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels and spot urine samples for urinary iodine excretion were taken at the same time as blood collection.Results. The median urinary iodine concentration (UIC) for all women was 81 μg/l (interquartile range 41–169 μg/l). 71.9% of the women exhibited a UIC of <150 μg/l. 26% of the women had a UIC <50 μg/l, and 12% had a UIC <20 μg/l. The only detectable influences on UIC were daily milk intake and pregnancy supplements. There was no statistically significant association between UIC and thyroid function and no evidence for an effect of iodine intake on thyroid function.Conclusions. There is a high prevalence of mild to moderate iodine deficiency in women in Western Sydney but no evidence for a significant adverse effect on thyroid function. The 6.5% prevalence of subclinical hypothyroidism is unlikely to be due to iodine deficiency.

scholarly journals Indicators of Iodine Status in Pregnancy and Postpartum in a Group of Pregnant Women from Perimarine Area of Romania

2020 ◽  
Vol 26 (2) ◽  
pp. 63-69
Author(s):  
Scrinic Olesea ◽  
Delia Corina Elena ◽  
Toma Geanina Mirela ◽  
Circo Eduard
Keyword(s):  
Pregnant Women ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Iodine Intake ◽  
Iodized Salt ◽  
Urinary Iodine Concentration ◽  
Urinary Creatinine ◽  
Iodine Status ◽  
In Pregnancy

Abstract Objective: Assessment of iodine nutritional status in pregnant women in the perimarine area of Romania, a region without iodine deficiency. Adequate iodine intake is the main source for normal thyroid function, ensuring the need for maternal thyroid hormones during pregnancy, but also for the development and growth of children in the fetal and postpartum period. Material and method: Prospective study performed on 74 pregnant women in the first 2 trimesters of pregnancy, originating from the perimarin area. The following indicators of iodine status were analyzed: urinary iodine concentration (UIC), the ratio between urinary iodine concentration and urinary creatinine (UIC/UCr), the prevalence of maternal goiter and the value of neonatal TSH (thyroid stimulating hormone). Results: The mean gestational age was 11 weeks. The ways of iodine intake are: iodized salt - 59.4%, iodized salt and iodine supplements- 23%, only iodine supplements -10.8% and 6.8% consume only non-iodized salt. The median of UIC was 133.03 mcg/l considered insufficient iodine intake (normal in pregnancy UIC >150 mcg/l), but the adjustment of UIC to urinary creatinine reveals a median of 152.83 mcg/g, a value that reflects an adequate iodine intake. The prevalence of goiter was 25.6% characteristic for a moderate iodine deficiency. The prevalence of neonatal TSH >5 mIU/L was registered in 18.8% characteristic of mild iodine deficiency. Conclusions: Monitoring of the iodine nutritional status is recommended for the prevention of disorders due to iodine deficiency under the conditions of universal salt iodization. Perimarine areas considered sufficient in iodine may show variations in iodine status in subpopulations under certain physiological conditions, such as pregnancy. An indicator of iodine status of the population is UIC, but the UIC/UCr ratio may be a more optimal indicator for pregnant women, to avoid possible overestimated results of iodine deficiency in pregnancy.

scholarly journals Women Remain at Risk of Iodine Deficiency during Pregnancy: The Importance of Iodine Supplementation before Conception and Throughout Gestation

Nutrients ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 172 ◽  
Author(s):  
Kristen Hynes ◽  
Judy Seal ◽  
Petr Otahal ◽  
Wendy Oddy ◽  
John Burgess
Keyword(s):  
At Risk ◽  
Pregnant Women ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Urinary Iodine Concentration ◽  
Iodine Nutrition ◽  
Supplement Use ◽  
Iodine Supplementation ◽  
The Impact

In Australia, pregnant women are advised to take an iodine supplement (I-supp) (150 µg/day) to reduce risks to the foetus associated with iodine deficiency (ID). To examine the impact of this recommendation on iodine status, and to identify factors that contribute to adequacy during gestation, supplement use and Urinary Iodine Concentration (UIC) was measured in 255 pregnant women (gestation range 6 to 41 weeks) in Tasmania. The median UIC (MUIC) of 133 µg/L (Inter-quartile range 82–233) was indicative of ID, being below the 150–249 µg/L range for adequacy during pregnancy. Women taking an iodine-containing-supplement (I-supp) had a significantly higher MUIC (155 µg/L) (n = 171) compared to the combined MUIC (112.5 µg/L) (n = 84) of those who had never (120 µg/L) (n = 61) or were no longer taking an I-supp (90 µg/L) (n = 23) (p = 0.017). Among women reporting I-supp use, the MUIC of those commencing the recommended 150 µg/day prior to conception was significantly higher than those starting supplementation following pregnancy confirmation: 196 (98–315) µg/L (n = 45) versus 137.5 (82.5–233.5) µg/L (n = 124), p = 0.032. Despite recommendations for iodine supplementation pregnant Tasmanian women remain at risk of ID. Commencing an I-supp of 150 µg/day prior to conception and continuing throughout pregnancy is required to ensure adequacy. Timely advice regarding the importance of adequate iodine nutrition, including supplementation is needed to reduce the risk of irreversible in utero neurocognitive damage to the foetus.

scholarly journals High prevalence of iodine deficiency in pregnant women living in adequate iodine area

2018 ◽  
Vol 7 (5) ◽  
pp. 762-767 ◽  
Author(s):  
Verônica Carneiro Borges Mioto ◽  
Ana Carolina de Castro Nassif Gomes Monteiro ◽  
Rosalinda Yossie Asato de Camargo ◽  
Andréia Rodrigues Borel ◽  
Regina Maria Catarino ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Thyroid Volume ◽  
Adverse Outcomes ◽  
Urinary Iodine Concentration ◽  
Serum Thyroglobulin ◽  
Cross Sectional ◽  
Iodine Status

Objectives Iodine deficiency during pregnancy is associated with obstetric and neonatal adverse outcomes. Serum thyroglobulin (sTg) and thyroid volume (TV) are optional tools to urinary iodine concentration (UIC) for defining iodine status. This cross-sectional study aims to evaluate the iodine status of pregnant women living in iodine-adequate area by spot UIC and correlation with sTg, TV and thyroid function. Methods Two hundred and seventy-three pregnant women were evaluated at three trimesters. All had no previous thyroid disease, no iodine supplementation and negative thyroperoxidase and thyroglobulin antibodies. Thyroid function and sTg were measured using electrochemiluminescence immunoassays. TV was determined by ultrasonography; UIC was determined using a modified Sandell–Kolthoff method. Results Median UIC was 146 µg/L, being 52% iodine deficient and only 4% excessive. TSH values were 1.50 ± 0.92, 1.50 ± 0.92 and 1.91 ± 0.96 mIU/L, respectively, in each trimester (P = 0.001). sTg did not change significantly during trimesters with median 11.2 ng/mL and only 3.3% had above 40 ng/mL. Mean TV was 9.3 ± 3.4 mL, which positively correlated with body mass index, but not with sTg. Only 4.5% presented with goitre. When pregnant women were categorized as iodine deficient (UIC < 150 µg/L), adequate (≥150 and <250 µg/L) and excessive (≥250 µg/L), sTg, thyroid hormones and TV at each trimester showed no statistical differences. Conclusions Iodine deficiency was detected frequently in pregnant women living in iodine-adequate area. sTg concentration and TV did not correlate to UIC. Our observation also demonstrated that the Brazilian salt-iodization programme prevents deficiency, but does not maintain iodine status within adequate and recommended ranges for pregnant women.

scholarly journals Evaluation of Urinary Iodine Concentration for Predicting Iodine Deficiency in Sub-Saharan Africa: First Population Based Study From the Demographic and Health Surveys Data (P10-089-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Djibril Ba ◽  
Paddy Ssentongo ◽  
Guodong Liu ◽  
Ping Du ◽  
Xiang Gao
Keyword(s):  
Pregnant Women ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Reproductive Age ◽  
Sub Saharan Africa ◽  
Demographic And Health Surveys ◽  
Urinary Iodine Concentration ◽  
Factors Associated ◽  
Sub Saharan

Abstract Objectives Approximately 2 billion individuals suffer from an insufficient iodine intake, and sub-Saharan Africa is particularly the most affected. We thus conducted a cross-sectional study to assess iodine deficiency status, among women of reproductive age 20–49 years in Tanzania and examine the factors associated with iodine deficiency. Methods The current analysis was based on 3057 women aged 20–49 y who participated the Tanzania Demographic and Health Surveys 2015–2016. Iodine status was assessed using urinary iodine concentration (UIC). Iodine deficiency was defined if UIC was less than 100ug/L. A stepwise multivariable logistic regression to identify the factors associated with iodine deficiency. Potential predicators included age, education level, married status, wealth index, having a prenatal doctor and prenatal nurse, currently pregnant, currently breastfeeding, place of residence, employment status, and history of terminated pregnancy. Results The median UIC among pregnant women (median: 129 μg/L; 25th and 75th percentile: 57.8–240), uneducated women (99.0 μg/L; 48.2–201 μg/L), and poor women (92 μg/L; 43.1 -191 μg/L) were below the recommended ranges (≥150 μg/L for pregnant women and ≥100 μg/L for non-pregnant women) by the World Health Organization. Multivariable logistic stepwise regression showed that women were more likely to be iodine deficient if they were pregnant (aOR 1.55 [95% CI 1.11, 2.15], currently breastfeeding (aOR 1.56 [95% CI 1.28, 1.92], poor (aOR 1.75 [95% CI 1.35, 2.26], uneducated (aOR 1.77 [95% CI 1.26, 2.48], and living in the rural area (aOR 1.79 [95% CI 1.37, 2.34]. Unexpectedly, currently employed women also had significantly higher odds of iodine deficient (aOR 1.41 [95% CI 1.10, 1.80], relative to those without employment. Conclusions There is disparity in UIC among of women of reproductive age 20–49 in Tanzania. Poverty and lack of education appeared to be the driving factors for iodine deficiency. High risk of iodine deficient among pregnant and breastfeeding women appeal for action to implement and enforce universal salt iodization among this vulnerable population in Tanzania. Funding Sources There was no external or internal funding to support this study.

scholarly journals Longitudinal trends in thyroid function in relation to iodine intake: ongoing changes of thyroid function despite adequate current iodine status

2014 ◽  
Vol 170 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Annenienke C van de Ven ◽  
Romana T Netea-Maier ◽  
H Alec Ross ◽  
Teun A E van Herwaarden ◽  
Suzanne Holewijn ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Intake ◽  
Thyroid Peroxidase ◽  
Urinary Iodine Concentration ◽  
Creatinine Concentration ◽  
Iodine Status ◽  
The Past ◽  
Urine Iodine

ObjectiveSeveral cross-sectional studies on populations with iodine deficiency showed that TSH-levels are negatively associated with age, while in populations with high iodine intake TSH is positively associated with age. The question is whether such an age-thyroid function relation is an ongoing process apparent also in longitudinal studies and whether it reflects an actual iodine deficiency or an iodine insufficiency in the past.MethodsIn an area with a borderline iodine status in the past, we studied 980 participants of the Nijmegen Biomedical Study. We measured serum TSH, free thyroxine (FT4), total triiodothyronine (T3), peroxidase antibodies, and the urine iodine and creatinine concentration 4 years after our initial survey of thyroid function, in which we reported a negative association between TSH and age.ResultsWithin 4 years, TSH decreased by 5.4% (95% CI 2.5–8.3%) and FT4increased by 3.7% (95% CI 2.9–4.6%). Median urinary iodine concentration was 130 μg/l. Estimated 24-h iodine excretion was not associated with TSH, T3, change of TSH, or FT4over time or with the presence of antibodies against thyroid peroxidase. Only FT4appeared to be somewhat higher at lower urine iodine levels: a 1.01% (95% CI 0.17–1.84%) higher FT4for each lower iodine quintile.ConclusionsIn this longitudinal study, we found an ongoing decrease in TSH and increase in FT4in a previously iodine insufficient population, despite the adequate iodine status at present. This suggests that low iodine intake at young age leads to thyroid autonomy (and a tendency to hyperthyroidism) that persists despite normal iodine intake later in life.

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