Use Of Iodine Supplements Research Articles

Folic acid and iodine supplement use from preconception through to six weeks postpartum in New Zealand women

Folic acid (FA) and iodine supplements are recommended by the Ministry of Health (MOH) for pregnant and/or lactating women in New Zealand (NZ)(1). Evidence suggests that many NZ women are not just taking FA and iodine in the form of a single-nutrient supplement (SNS) but are taking FA and iodine as part of a multivitamin supplement (MVS) which may or may not contain the recommended doses, and some are using a combination of both(2). No NZ study has examined the daily dose taken from both SNS and MVS for both FA and iodine across all time periods (2, 3). The aim of this study was to investigate what nutritional supplements containing FA and iodine were taken by postpartum NZ women, preconception, during the three trimesters of pregnancy and post-partum, and examine how well the women’s supplement use aligned with the NZ MOH recommendations. This cross-sectional observational study utilised data gathered on FA and iodine supplement use from an anonymous survey between February and August 2022. Descriptive statistics including frequency and percentages were reported. Folic acid and iodine weekly intakes from SNS and MVS were calculated by multiplying the amount of nutrient in each supplement, with the number of times per day taken, and the average number of days taken per week reported. A total of 584 women were included in the analysis. In addition to the SNS for FA (0.8mg and 5mg) and iodine (150 ug), women took 28 different MVS. Fifty-eight percent (preconception; 30% from SNS, 18% from MVS, and 10% from both) and 96% (1st trimester pregnancy; 61% from SNS, 17% from MVS, and 19% from both) of women took FA containing supplements. More than 75% of women reported taking iodine containing supplements during pregnancy (1st and 2nd trimesters: 93%, 3rd trimester: 89%) and postpartum (76%).Approximately 60% took SNS, 18% took only MVS and 14% took both. Based on the MOH recommendations, only 30% (preconception) and 62% (1st trimester) achieved sufficiency of FA supplementation at 0.8mg/day; 35% (preconception) and 69% (1st trimester) achieved sufficiency of FA at 5mg/day; around 50% women achieved sufficiency of iodine supplementation at 150 µg/day during pregnancy while only 37% during postpartum. The balance either took none, an insufficient dose or a dose that exceeded the recommended dose and many took them during non-recommended periods (FA after the 1st trimester; iodine preconception). Most women reported taking FA and/or iodine containing supplements at some point before, during and after their pregnancy. However, it is concerning that a large number of women do not seem to be adhering to the MOH recommendations for FA and iodine supplementation.

Exploration of thyroglobulin as a biomarker of iodine status in iodine-sufficient and mildly iodine-deficient pregnant women

PurposeUrinary iodine-to-creatinine ratio (UI/Creat) reflects recent iodine intake but has limitations for assessing habitual intake. Thyroglobulin (Tg) concentration, which increases with thyroid size, appears to be an indicator of longer-term iodine status in children and adults, however, less is known in pregnancy. This study investigated the determinants of serum-Tg in pregnancy and its use as an iodine-status biomarker in settings of iodine-sufficiency and mild-to-moderate deficiency.MethodsStored blood samples and existing data from pregnant women from the Netherlands-based Generation R (iodine-sufficient) and the Spain-based INMA (mildly-to-moderately iodine-deficient) cohorts were used. Serum-Tg and iodine status (as spot-urine UI/Creat) were measured at median 13 gestational weeks. Using regression models, maternal socio-demographics, diet and iodine-supplement use were investigated as determinants of serum-Tg, as well as the association between UI/Creat and serum-Tg.ResultsMedian serum-Tg was 11.1 ng/ml in Generation R (n = 3548) and 11.5 ng/ml in INMA (n = 1168). When using 150 µg/g threshold for iodine deficiency, serum-Tg was higher in women with UI/Creat < 150 vs ≥ 150 µg/g (Generation R, 12.0 vs 10.4 ng/ml, P = 0.010; INMA, 12.8 vs 10.4 ng/ml, P < 0.001); after confounder adjustment, serum-Tg was still higher when UI/Creat < 150 µg/g (regression coefficients: Generation R, B = 0.111, P = 0.050; INMA, B = 0.157, P = 0.010). Iodine-supplement use and milk intake were negatively associated with serum-Tg, whereas smoking was positively associated.ConclusionThe association between iodine status and serum-Tg was stronger in the iodine-deficient cohort, than in the iodine-sufficient cohort. Serum-Tg might be a complementary (to UI/Creat) biomarker of iodine status in pregnancy but further evidence is needed.

Mild-to-moderate iodine deficiency and symptoms of emotional distress and depression in pregnancy and six months postpartum – Results from a large pregnancy cohort

BackgroundThe relationship between iodine intake and depression is unknown. The aim of the present study was to investigate whether iodine intake was associated with symptoms of perinatal emotional distress and depression in a mild- to moderately iodine deficient population. MethodsThe study population comprised 67,812 women with 77,927 pregnancies participating in the Norwegian Mother, Father and Child Cohort Study. Self-reported emotional distress and depressive symptoms were reported in pregnancy and at six months postpartum. Iodine intake was assessed by a food frequency questionnaire in mid-pregnancy. Urinary iodine concentration (UIC) was available for 2792 pregnancies. ResultsThe median iodine intake from food was 121 μg/day and the median UIC was 68 μg/L. The prevalence of high scores for emotional distress was 6.6 % in pregnancy and 5.8 % six months postpartum, and for high scores on postpartum depression it was 10.3 %. In non-users of iodine supplements (63 %), a low maternal iodine intake from food (lower than ~100–150 μg/day) was associated with increased risk of high scores of emotional distress and depression both in pregnancy and six months postpartum (p < 0.001). Iodine supplement use was associated with increased risk of high scores of emotional distress in pregnancy compared to no supplement use or use of supplements without iodine. LimitationsObservational design, self-report information, and short scales to assess symptoms of emotional distress and depression. ConclusionA low habitual iodine intake was associated with increased prevalence of perinatal emotional distress and depression. The potential non-beneficial effect of iodine supplements may have biological explanations. More studies are needed.

Iodine Nutrition and Iodine Supplement Initiation in Association with Thyroid Function in Mildly-to-Moderately Iodine-Deficient Pregnant and Postpartum Women

BackgroundWhereas the adverse effects of severe iodine deficiency during pregnancy are well documented, the effects of mild-to-moderate deficiency are not well established. ObjectivesWe aimed to explore whether iodine nutrition and timing of iodine supplement initiation are associated with thyroid function in pregnant and postpartum women. MethodsIn this cohort study, 137 pregnant women were enrolled and followed up at gestational weeks (GWs) 18 and 36, and 3 and 6 mo postpartum. Thyroid function tests [thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4)], urinary iodine and creatinine concentration (UIC:Cr), and iodine intake (including iodine supplement use) were measured at each time point. The associations between thyroid hormone concentrations and UIC:Cr, iodine intakes, and iodine supplement use were estimated using multiple generalized estimating equation models. ResultsThe median UIC at GW18 was 94 μg/L, indicating mild-to-moderate iodine deficiency. UIC:Cr (β; 95% CI) per 100 μg/g was negatively associated with fT3 (−0.191; −0.331, −0.051) and fT4 (−0.756; −1.372, −0.141) concentrations. Iodine intake (β; 95% CI) per 100 μg/d was positively associated with TSH (0.099; 0.022, 0.177), and negatively associated with fT3 (−0.084; −0.0141, −0.027) and fT4 (−0.390; −0.599, −0.182) concentrations. Compared with no use of supplement, those initiating an iodine-containing supplement prepregnancy and continuing through pregnancy had lower TSH (estimated means) (1.35 compared with 1.68 mIU/L, P = 0.021), and higher fT3 (4.48 compared with 4.28 pmol/L, P = 0.035) and fT4 (15.2 compared with 14.4 pmol/L, P = 0.024) concentrations. ConclusionsLower iodine availability during pregnancy and postpartum was associated with lower TSH, and higher fT3 and fT4 concentrations. The use of an iodine-containing supplement that was initiated prepregnancy and continuing through pregnancy was associated with lower TSH, and higher fT3 and fT4 concentrations, which may suggest improved thyroid function. These findings support the notion that optimization of iodine intake should start before pregnancy.This trial was registered at clinicaltrials.gov as NCT02610959.

Iodine supplementation: compliance and association with adverse obstetric and neonatal outcomes.

ObjectivesOver 1.9 billion people worldwide are living in areas estimated to be iodine insufficient. Strategies for iodine supplementation include campaigns targeting vulnerable groups, such as women in pre-conception, pregnancy and lactation. Portuguese women of childbearing age and pregnant women were shown to be mildly-to-moderately iodine deficient. As a response, in 2013, the National Health Authority (NHA) issued a recommendation that all women considering pregnancy, pregnant or breastfeeding, take a daily supplement of 150–200 μg iodine. This study explored how the iodine supplementation recommendation has been fulfilled among pregnant and lactating women in Portugal, and whether the reported iodine supplements intake impacted on adverse obstetric and neonatal outcomes.Design and methodsObservational retrospective study on pregnant women who delivered or had a fetal loss in the Braga Hospital and had their pregnancies followed in Family Health Units.ResultsThe use of iodine supplements increased from 25% before the recommendation to 81% after the recommendation. This was mostly due to an increase in the use of supplements containing iodine only. Iodine supplementation was protective for the number of adverse obstetric outcomes (odds ratio (OR) = 0.791, P = 0.018) and for neonatal morbidities (OR = 0.528, P = 0.024) after controlling for relevant confounding variables.ConclusionThe recommendation seems to have succeeded in implementing iodine supplementation during pregnancy. National prospective studies are now needed to evaluate the impact of iodine supplementation on maternal thyroid homeostasis and offspring psychomotor development and on whether the time of the beginning of iodine supplementation (how early during preconception or pregnancy) is relevant to consider.

Йодний дефіцит у світі та в Україні: поточний стан проблеми

Today, efforts of governments and communities are aimed at coping with severe impacts of new viral disease outbreaks caused by SARS-Cov-2. However, there are gaps in care for patients with many chronic diseases, and programs to prevent the most common conditions are being prevented or stopped. This applies to diseases directly related to eating disorders. To solve the problem at the population level, it is critically necessary to adopt legislative acts regulating the universal iodization of table salt in the country. Currently, in Ukraine, potassium iodate is used for salt enrichment, which is a more stable compound than iodide that was used earlier. Potassium iodate allows you to store iodized salt for a year or more, does not change the taste and smell of food, and can be used for preserving and storing food. For the most vulnerable categories of the population (newborns, children, pregnant women and mothers who are breastfeeding), the use of iodine supplements remains relevant. The optimal tool for such preventive interventions is supplements containing the physiological dose of iodine. On the Ukrainian market, they are presented in the form of pills of potassium iodide with a content of 100 mcg and 200 mcg of iodine. The common goal should be Ukraine without iodine deficiency, where each person receives the amount of iodine corresponding to their needs, and children are provided with the opportunity for adequate intellectual development. No conflict of interest was declared by the authors. Key words: children, pregnant women, iodine deficiency, iodine supplements.

Vegans, Vegetarians and Pescatarians Are at Risk of Iodine Deficiency in Norway.

Low iodine intakes have been documented in different population groups in Norway. We aimed to assess iodine status, dietary intake, supplement and macroalgae use, and iodine knowledge in vegans, vegetarians and pescatarians. In this study, 115 vegans, 55 vegetarians and 35 pescatarians from the Oslo region of Norway, aged 18–60 years, participated. A spot urine sample was collected along with a dietary assessment of iodine intake, supplement and macroalgae use. The median urinary iodine concentration (MUIC) in vegans was 43 µg/L (moderate iodine deficiency), in vegetarians 67 µg/L and in pescatarians 96 µg/L (mild iodine deficiency). In multiple linear regression analysis, use of iodine supplements was one of the strongest predictors of UIC. About half of the participants had median 24-h iodine intakes below estimated average requirement (EAR) of 100 µg/day. Fifty percent had low knowledge score, while 27% had very low knowledge score. Vegans, vegetarians and possibly pescatarians in Norway, are unable to reach the recommended iodine intake merely from food and are dependent on iodine supplements. There is an urgent need for dietary guidance targeting vegans, vegetarians and pescatarians to avoid inadequate iodine intake in non-supplement users, as well as avoiding excess iodine intake in macroalgae users.

Insufficient maternal iodine intake is associated with subfecundity, reduced foetal growth, and adverse pregnancy outcomes in the Norwegian Mother, Father and Child Cohort Study

BackgroundSevere iodine deficiency impacts fertility and reproductive outcomes. The potential effects of mild-to-moderate iodine deficiency are not well known. The aim of this study was to examine whether iodine intake was associated with subfecundity (i.e. > 12 months trying to get pregnant), foetal growth, and adverse pregnancy outcomes in a mild-to-moderately iodine-deficient population.MethodsWe used the Norwegian Mother, Father and Child Cohort Study (MoBa) and included 78,318 pregnancies with data on iodine intake and pregnancy outcomes. Iodine intake was calculated using an extensive food frequency questionnaire in mid-pregnancy. In addition, urinary iodine concentration was available in a subsample of 2795 pregnancies. Associations were modelled continuously by multivariable regression controlling for a range of confounding factors.ResultsThe median iodine intake from food was 121 μg/day and the median urinary iodine was 69 μg/L, confirming mild-to-moderate iodine deficiency. In non-users of iodine supplements (n = 49,187), low iodine intake (< 100–150 μg/day) was associated with increased risk of preeclampsia (aOR = 1.14 (95% CI 1.08, 1.22) at 75 vs. 100 μg/day, p overall < 0.001), preterm delivery before gestational week 37 (aOR = 1.10 (1.04, 1.16) at 75 vs. 100 μg/day, p overall = 0.003), and reduced foetal growth (− 0.08 SD (− 0.10, − 0.06) difference in birth weight z-score at 75 vs. 150 μg/day, p overall < 0.001), but not with early preterm delivery or intrauterine death. In planned pregnancies (n = 56,416), having an iodine intake lower than ~ 100 μg/day was associated with increased prevalence of subfecundity (aOR = 1.05 (1.01, 1.09) at 75 μg/day vs. 100 μg/day, p overall = 0.005). Long-term iodine supplement use (initiated before pregnancy) was associated with increased foetal growth (+ 0.05 SD (0.03, 0.07) on birth weight z-score, p < 0.001) and reduced risk of preeclampsia (aOR 0.85 (0.74, 0.98), p = 0.022), but not with the other adverse pregnancy outcomes. Urinary iodine concentration was not associated with any of the dichotomous outcomes, but positively associated with foetal growth (n = 2795, p overall = 0.017).ConclusionsThis study shows that a low iodine intake was associated with restricted foetal growth and a higher prevalence of preeclampsia in these mild-to-moderately iodine-deficient women. Results also indicated increased risk of subfecundity and preterm delivery. Initiating iodine supplement use in pregnancy may be too late.

Language delay and poorer school performance in children of mothers with inadequate iodine intake in pregnancy: results from follow-up at 8\xa0years in the Norwegian Mother and Child Cohort Study

PurposeSome studies indicate that mild-to-moderate iodine deficiency in pregnant women might negatively affect offspring neurocognitive development, including previous results from the Norwegian Mother and Child Cohort study (MoBa) exploring maternally reported child development at age 3 years. The aim of this follow-up study was to investigate whether maternal iodine intake in pregnancy is associated with language and learning at 8 years of age.MethodsThe study sample includes 39,471 mother–child pairs participating in MoBa with available information from a validated food frequency questionnaire covering the first half of pregnancy and a questionnaire on child neurocognitive development at 8 years. Multivariable regression was used to explore associations of iodine intake from food and supplements with maternally reported child outcomes.ResultsMaternal iodine intake from food less than ~ 150 µg/day was associated with poorer child language skills (p-overall = 0.013), reading skills (p-overall = 0.019), and writing skills (p-overall = 0.004) as well as poorer school test result in reading (p < 0.001), and increased likelihood of the child receiving special educational services (p-overall = 0.042) (in non-iodine supplement users). Although significant, differences were generally small. Maternal use of iodine supplements in pregnancy was not significantly associated with any of the outcomes.ConclusionsLow habitual iodine intake in pregnant women, i.e., lower than the recommended intake for non-pregnant women, was associated with mothers reporting poorer child language, school performance, and increased likelihood of special educational services. We found no indications of benefits or harm of using iodine-containing supplements in pregnancy. Initiating use in pregnancy might be too late.

Iodine-containing supplement use by pregnant women attending antenatal clinics in Western Australia.

Iodine requirements increase during pregnancy and although national recommendations for daily iodine supplementation (150µg) exist, there is no research related to the uptake of these recommendations by pregnant women in Western Australia. To investigate the use of iodine-containing supplements and associations with their use in a sample of Western Australian pregnant women. A cross-sectional study was conducted on pregnant women attending antenatal clinics in a public tertiary hospital for women and neonates in Perth during 2012 and 2013 (n=425). Women completed a self-administered questionnaire. Frequencies and percentages were obtained for categorical variables and χ2 tests conducted to assess associations between iodine-containing supplement use and sociodemographic and pregnancy-related factors. A total of 24% of pregnant women reported using iodine-containing supplements prior to pregnancy compared to 66% during the previous two months. Age and maternal income were associated with use prior to pregnancy only (P=0.004 and P=0.031) and first pregnancy was associated with use during pregnancy only (P=0.006). Ethnicity and reporting use in the first two trimesters were associated with the use of iodine supplements both in the year prior to pregnancy (P=0.002 and P=0.020, respectively) and during pregnancy (P<0.001 and P=0.001, respectively). Two-thirds of women reported use of iodine-containing supplements during pregnancy, within the range reported for other Australian states. One-quarter reported use prior to pregnancy. Public health strategies are required to promote awareness of the importance of iodine and supplementation both before and during the entire pregnancy.

Maternal iodine dietary supplements and neonatal thyroid stimulating hormone in Gippsland, Australia.

Pregnant women are at particular risk of iodine deficiency due to their higher iodine requirements. Iodine is known to be essential for normal growth and brain development, therefore neonatal outcomes in mildly iodine deficient areas, such as Gippsland, are a critical consideration. This study aimed to investigate whether iodine supplementation prevented iodine insufficiency as determined by neonatal thyroid stimulating hormone (TSH) screening criteria. Gippsland-based women aged >=18 years, in their third trimester of pregnancy, provided self-reported information regarding their iodine supplement use and consent to access their offspring's neonatal TSH screening data. 126 women consented to participate, with 111 women completing all components of this study. Only 18.9% of participants followed the National Health and Medical Research Council (NHMRC) recommendation of 150 μg/day iodine supplement, with 42.3% of participants not taking any supplements, or taking supplements with no iodine or insufficient iodine. The remaining women (38.7%) were taking supplements with doses of iodine much higher (200-300 μg) than the NHMRC recommended dose or were taking multiple supplements containing iodine. When correlating iodine intake to their neonates' TSH, no correlation was found. When iodine supplementation usage was categorised as below, equal to, or above NHMRC recommendations there was no significant difference in neonatal TSH. This study found that iodine supplementation appeared to prevent maternal iodine insufficiency when measured against neonatal TSH screening criteria.

Maternal Iodine Intake and Offspring Attention-Deficit/Hyperactivity Disorder: Results from a Large Prospective Cohort Study.

Current knowledge about the relationship between mild to moderately inadequate maternal iodine intake and/or supplemental iodine on child neurodevelopment is sparse. Using information from 77,164 mother-child pairs in the Norwegian Mother and Child Cohort Study, this study explored associations between maternal iodine intake and child attention-deficit/hyperactivity disorder (ADHD) diagnosis, registered in the Norwegian Patient Registry and maternally-reported child ADHD symptoms at eight years of age. Pregnant women reported food and supplement intakes by questionnaire in gestational week 22. In total, 1725 children (2.2%) were diagnosed with ADHD. In non-users of supplemental iodine (53,360 mothers), we found no association between iodine intake from food and risk of child ADHD diagnosis (p = 0.89), while low iodine from food (<200 µg/day) was associated with higher child ADHD symptom scores (adjusted difference in score up to 0.08 standard deviation (SD), p < 0.001, n = 19,086). In the total sample, we found no evidence of beneficial effects of maternal use of iodine-containing supplements (n = 23,804) on child ADHD diagnosis or symptom score. Initiation of iodine supplement use in gestational weeks 0–12 was associated with an increased risk of child ADHD (both measures). In conclusion, insufficient maternal iodine intake was associated with increased child ADHD symptom scores at eight years of age, but not with ADHD diagnosis. No reduction of risk was associated with maternal iodine supplement use.

Development and validation of an iodine-specific FFQ to estimate iodine intake in Australian pregnant women.

Adequate iodine is important during pregnancy to ensure optimal growth and development of the offspring. We validated an iodine-specific FFQ (I-FFQ) for use in Australian pregnant women. A forty-four-item I-FFQ was developed to assess iodine intake from food and was administered to 122 pregnant women at 28 weeks gestation. Iodine supplement use was captured separately at 28 weeks gestation. Correlation between iodine intake from food estimated using the I-FFQ and a 4 d weighed food record as well as correlation between total iodine intake and 24 h urinary iodine excretion (UIE), 24 h urinary iodine concentration (UIC), spot UIC and thyroid function were assessed at 28 weeks gestation. A moderate correlation between the two dietary methods was shown (r 0·349, P< 0·001), and it was strengthened with the addition of iodine supplements (r 0·876, P<0·001). There was a fair agreement (k= 0·28, P<0·001) between the two dietary measures in the classification of women as receiving adequate (≥160 μg/d) or inadequate (<160 μg/d) iodine intake from food, but the limits of agreement from the Bland-Altman plot were large. Total iodine intake was associated with 24 h UIE (β = 0·488, P<0·001) but not with spot UIC. Iodine intake from food using the I-FFQ was assessed at study entry (<20 weeks gestation) in addition to 28 weeks gestation, and there was a strong correlation in iodine intake at the two time points (r 0·622, P<0·001), which indicated good reproducibility. In conclusion, the I-FFQ provides a valid tool for estimating iodine intake in pregnant women and can be used to screen women who are at risk of inadequate intake.

Synergism between exposure to mercury and use of iodine supplements on thyroid hormones in pregnant women

ObjectiveTo evaluate the association between mercury exposure and thyroid-stimulating hormone (TSH), total triiodothyronine (TT3) and free thyroxine (FT4) levels during pregnancy as well as to explore if there is any synergic action between mercury and intake of iodine from different sources. MethodsThe study population was 1407 pregnant women participating in the Spanish INMA birth cohort study. Total mercury concentrations were analyzed in cord blood. Thyroid hormones (THs) were measured in serum samples collected at 13.2±1.5 weeks of gestation. The association between mercury and TH levels was evaluated with multivariate linear regression models. Effect modification caused by iodine intake from supplements and diet was also evaluated. ResultsThe geometric means of TSH, TT3, FT4 and mercury were 1.1μU/L, 2.4nmol/L, 10.5pmol/L and 7.7μg/L, respectively. Mercury levels were marginally significantly associated with TT3 (β: −0.05; 95%CI: −0.10, 0.01), but were neither associated with TSH nor FT4. The inverse association between mercury and TT3 levels was stronger among the iodine supplement consumers (−0.08; 95%CI: −0.15, −0.02, interaction p-value=0.07). The association with FT4 followed the same pattern, albeit not significant. ConclusionPrenatal mercury exposure was inversely associated with TT3 levels among women who took iodine supplements during pregnancy. These results could be of public health concern, although further research is needed.

Health knowledge and iodine intake in pregnancy

Pregnant women have much higher iodine requirements as compared to all other population groups. The National Health and Medical Research Council (NHMRC) recommends pregnant women take a daily iodine supplement of 150μg to meet their high iodine requirements. To investigate iodine supplement use and health knowledge among pregnant women. A cross-sectional sample of 200 pregnant women aged 18years or older, in their third trimester based in Gippsland (Victoria, Australia) undertook a self-administered questionnaire from August 2011-May 2012. The women were recruited from antenatal classes and clinics from all birthing hospitals across Gippsland. Data were analysed using descriptive statistics and logistic regression. A total of 46% of participants did not follow the NHMRC recommendation of 150μg/day iodine supplement. The participants lacked knowledge about iodine and the need for supplementation. Only 18.5% of pregnant women believed they needed an iodine supplement. The majority of participants (83.5%) indicated their medical practitioners were the main source of health information, yet only 34.5% indicated being made aware of the importance of increasing iodine intake during pregnancy by their medical practitioner. The predictors of iodine supplementation are general supplementation use and knowledge of the importance of iodine. Despite NHMRC guidelines for iodine supplementation during pregnancy, many women were not taking a sufficient iodine supplement. Pregnant women may be inclined to take an iodine supplement if they had greater knowledge of their increased iodine needs during pregnancy. Medical practitioners are best placed to provide this information to pregnant women.

Mandatory iodine fortification of bread and salt increases iodine excretion in adults in Denmark – A 11-year follow-up study

Iodine fortification is widespread. Systematic monitoring of iodine fortification programs should be carried out to secure an optimal fortification level. Our aim was to investigate the effectiveness of the Danish iodine fortification program by comparing iodine excretion at baseline and at 11-year follow-up, and to study determinants for any change in iodine intake including dietary habits, education, life style factors and health parameters. A follow-up study based on the Danish DanThyr cohort examined in 1997-1998 just before iodine fortification was introduced, and reexamined in 2008-2010. In total, 2465 (59.1%) adult participants were reexamined. Median (IQR) iodine concentration in urine had increased by 19 (-25-68) μg/L to 83 (47-133) μg/L. Estimated 24-hiodine excretion had increased by 36 (-21-95) μg/24-hto 134 (93-206), and calculated total iodine intake (diet plus supplements) had increased by 16 (-18-48) μg/day. Iodine excretion had increased significantly in all age and gender groups, but was still below the recommended amount at follow-up. The increase in iodine excretion was positively associated with changes in milk intake, with changes in the use of iodine supplements, and with bread intake at follow-up. Salt intake, education, self-rated health, smoking, alcohol intake and physical activity were not associated with the increase in iodine excretion. The strategy to combat iodine deficiency in Denmark seems to be working because the fortification led to increased urinary iodine excretion in (almost) all participants. However, the level of iodine fortification of salt is too low.

Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study

To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3). Population-based study of thyrotoxicosis at disease onset. In the period 1997-2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082). Untreated levels of serum T3, T4, and T3:T4 ratio were compared and related to sex, age, level of iodine deficiency, smoking status, alcohol intake, iodine supplement use, co-morbidity, and TSH receptor antibodies (TRAbs) in multivariate models. Graves' disease (GD) patients had much higher levels of T3 and higher T3:T4 ratio at diagnosis compared with other thyrotoxic patients, but with a profound negative association between hormone levels and age. In GD, patients diagnosed in the area with more severe iodine deficiency had lower levels of T3 and T4. TRAb-negative GD patients had biochemically mild thyrotoxicosis. Higher age was also associated with lower degree of biochemical thyrotoxicosis in nodular toxic goiter. We found no association between serum T3 and T4 and sex, smoking habits, iodine supplements, alcohol intake, or co-morbidity in any type of thyrotoxicosis. The study gives new insight into the hormonal presentation of thyrotoxicosis and showed that young age, positive TRAb levels, but also residency in the area with higher iodine intake was positively associated with biochemical disruption in GD.

Mild iodine deficiency in women after spontaneous abortions living in an iodine‐sufficient area of Czech Republic: prevalence and impact on reproductive health

Iodine deficiency is associated with thyroid dysfunction and adverse pregnancy outcomes. The aim of our study was to investigate the status of iodine saturation in women after spontaneous abortion (SpA) residing in an iodine-sufficient area and to evaluate their subsequent reproductive health. Nonrandomized prospective follow-up study. We compared urinary iodine concentration (UIC) in 171 women 2-8 weeks (median 4) after an early SpA with age-matched controls. Women with known thyroid diseases were excluded. We also analysed a relationship of UIC to serum thyroid-stimulating hormone, free thyroxine, antibodies against thyroid peroxidase and thyroid ultrasound. Afterwards, we followed the women for a median of 38 months (range 12-47). We used a multivariate regression analysis to assess the influence of iodine status and other thyroid biochemical and ultrasound parameters on their subsequent reproductive health. Women after SpA were almost twice as likely to suffer from mild iodine deficiency and had lower median UIC as compared to age-matched controls [rate 105/181 (58·0%) vs 57/181 (31·5%), P < 0·001, medians UIC 92·00 vs 117·80 mcg/l, P < 0·001]. UIC was not influenced by the use of iodine supplements in the previous pregnancy. We did not find any association neither between UIC and thyroid dysfunction and/or thyroid antibodies, nor between UIC and rates of subsequent successful pregnancies or obstetric complications. More than half of women after SpA residing in an iodine-sufficient area are suffering from mild iodine deficiency. However, it does not seem to have a negative impact on their subsequent reproductive health.

Poor knowledge and dietary practices related to iodine in breastfeeding mothers a year after introduction of mandatory fortification

AbstractAim: Public health has refocused attention on low iodine status of vulnerable groups. The purpose of this research was to identify knowledge and dietary practices related to iodine nutrition in breastfeeding women in the Illawarra region following introduction of the mandatory iodine fortification programme.Methods: A cross‐sectional study was undertaken at four early childhood centres. Sixty mothers in their first six months of breastfeeding completed a short knowledge questionnaire, an iodine‐specific food frequency questionnaire, and reported use of nutritional supplements.Results: The women were generally limited in their ability to identify good dietary sources of iodine such as milk and bread but 45 women (75%) correctly identified seafood as a good source. There was some confusion in identifying health problems associated with insufficient iodine intake. Mean reported iodine intake was 146 mg/day (standard deviation: 58 mg; range: 43–342 mg); 48 women (80%) had intakes below the estimated average requirement of 190 mg/day. After allowance was made for fortification of bread, mean iodine intake significantly increased to 182 mg/day (P &lt; 0.001) and the number of women having intakes below the estimated average requirement decreased to 36 (60%). Milk was the highest contributor to iodine intake, on average representing 62% of total iodine consumed. Only 27 (45%) mothers reported consuming supplements that contained iodine.Conclusion: The combination of inadequate knowledge regarding iodine and the limited use of iodine supplements highlights a potential public health issue of concern. However, mandatory fortification may be overcoming this knowledge and behaviour deficit.

Patterns of Iodine Intake and Urinary Iodine Concentrations During Pregnancy and Blood Thyroid-Stimulating Hormone Concentrations in the Newborn Progeny

Appropriate maternal intake of iodine during pregnancy is essential for maternal thyroxine production and thyroid status of the fetus. It should be possible to enhance iodine intake during pregnancy by using iodine fortified salt or taking iodine supplements. In the present report we determined the status of iodine nutrition in pregnant women who were stratified on the basis of their history of taking or not taking iodized salt or iodine supplements. The study was performed in Toledo (Spain), a region in which prior studies have noted borderline iodine sufficiency. Iodine nutrition was assessed by measuring urinary iodine concentration (UIC) and neonatal thyrotropin (TSH). UIC was measured in 525 pregnant women. They were grouped according to their history of iodine intake. Diet Group 1 patients (n = 69) did not take iodized salt or iodine supplements during pregnancy. Diet Group 2 patients (n = 75) took iodized salt but not iodine supplements during pregnancy. Diet Group 3 patients (n = 381) took iodine supplements during pregnancy. Plasma determinations included TSH, free thyroxine, thyroid peroxidase antibody, and thyroglobulin antibody. UIC was measured in a single urine sample from all the pregnant women. Neonatal TSH was measured in capillary spot blood from all the neonates as part of a screening for congenital metabolic abnormalities. The median UIC in all subjects was 164 μg/L (interquartile range [IR]: 116-245). The median UICs in Diet Groups 1, 2, and 3 were 134.5 (IR: 90-196), 146 (IR: 103-205), and 183 (IR: 124-261) μg/L, respectively (p = not significant [NS] for Diet Group 1 vs. 2; p < 0.01 for Diet Group 2 vs. 3; all other comparisons NS). The median (IR) TSH of the neonates in all Diet Groups was 1.0 (IR: 0.7-1.6) μU/mL. Only 2 neonates had blood TSH concentrations >5 mU/L. Neonatal blood TSH concentrations were similar in all Diet Groups. In a region with a history of borderline iodine deficiency the UICs were below 150 μg/L in a substantial percentage of pregnant women who did not take iodine supplements, regardless of whether or not they took iodized salt. Our results support the use of iodine supplements from the start of the pregnancy, or even before pregnancy in women who live in regions with a history of even small degrees of iodine deficiency. In addition, neonate TSH screening is not the best tool to assess whether the iodine status in populations is ideal.