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Iodine Deficiency During Pregnancy – many studies

Summary

  • RDA (minimum) says 220 ug of Iodine during pregnancy and 290 ug during breastfeeding
  • Many prenatal vitamins contain ZERO Iodine
  • Iodine is particularly needed in first 3 months of pregnancy, but some women do not start prenatal vitamins that early
  • Consensus: no best way to test for Iodine Deficiency
  • Disagree: >150 ug is needed during pregnancy, > 250 ug is needed
  • Disagree: Iodine loading is possible (otherwise it takes 9-12 months to restore levels)

Iodine sufficiency is needed very early in pregnancy to have a healthy infant
Iodine sufficiency can be obtained by

  1. Having Iodine supplements months BEFORE conception
    > 250 micrograms daily pregnant and lactating women
    (> 150 micrograms daily adult)
    Note: It appears to take many months to become Iodine sufficient at these dose levels
  2. Get a loading dose of iodine ASAP in pregnancy
    How mouch is a big question - appears that 15 milligram daily for ~1 week will do
    But this large of a loading dose may be too much for about 1% of women

Table of contents

See also VitaminDWiki


Iodine and Pregancy book - 2014

Preventing Birth Defects: Understanding the Iodine/Thyroid Hormone Connection
Nice book. Have been talking with the author, Eugene L Heyden RN


Maternal iodine insufficiency and adverse pregnancy outcomes - Sept 2015

Matern Child Nutr. 2015 Sep 1. doi: 10.1111/mcn.12211. [Epub ahead of print]
Charoenratana C1, Leelapat P2, Traisrisilp K1, Tongsong T1.

Iodine ug/Liter
of urine
< 150 > 150
Preterm birth18%10%
Low birthweight20%12%

This study aimed to assess the iodine status of pregnant women in each trimester and to compare the pregnancy outcomes between groups with iodine insufficiency and iodine sufficiency. Longitudinal study on urinary iodine concentration (UIC) in each trimester as well as comparison between women with iodine insufficiency (<150 mcg L-1 ) and iodine sufficiency was conducted.
Pregnant women without thyroid diseases who had not received iodine supplementation were recruited for UIC measurements in each trimester and were followed up for pregnancy outcomes. In the analysis of 384, 325 and 221 samples in the first, second and third trimester, the medians of UICs were 147.39, 157.01 and 153.07 mcg L-1 , respectively. Of 399 women, 174 (43.6%) had a UIC less than 150 mcg L-1 (suggesting iodine insufficiency) and 225 (56.4%) had a UIC greater than or equal to 150 mcg L-1 (suggesting iodine sufficiency). Of 390 women with availability of the final outcomes, 171 and 219 in the insufficiency and sufficiency group, respectively, the rates of preterm birth and low birthweight were significantly higher in the insufficiency group, 17.5% vs. 10.0% (P = 0.031) and 19.9% vs. 12.3% (P = 0.042), respectively. Logistic regression analysis showed that iodine status was an independent risk of preterm birth and low birthweight.
Finally, women with a UIC <100 mcg L-1 had a significantly higher rate of fetal growth restriction, 13/68 vs. 30/322 (P = 0.031). In northern Thailand, a great number of pregnant women had a median UIC less than 150 mcg L-1 and they had a higher risk of preterm birth and low birthweight. Finally, those with a median UIC of less than 100 mcg L-1 had a higher risk of fetal growth restriction.

PMID: 26332721

Publisher rents PDF for just $6

  • from the PDF: "it seemed unethical not to supplement iodine during pregnancy in this geographical area "
Pattern of adequacy in each trimester %
Insufficiency in all trimesters 21%
Insufficiency in the first two trimesters with dropout in the third trimester 13%
Insufficiency in the first trimesters with dropout in the last two trimesters 9%
Sufficiency in all trimesters 26%
Sufficiency in the first two trimesters with dropout in the third trimester 18%
Sufficiency in the first trimesters with dropout in the last two trimesters 9%

Status micrograms of Iodine
per liter of Urine
Insufficient <150
Adequate 150–249
Above requirement 250-499
Excessive > 500

60% increase chance of child being in lowest IQ quartile if < 150 ug of Iodine in early pregnancy - Aug 2015

The new emergence of iodine deficiency in the UK: consequences for child neurodevelopment.


Adding iodine during pregnancy immediately saves $300, and saves society $6,800 – Sept 2015

Costs and benefits of iodine supplementation for pregnant women in a mildly to moderately iodine-deficient population: a modelling analysis.
Lancet Diabetes Endocrinol. 2015 Sep;3(9):715-22. doi: 10.1016/S2213-8587(15)00212-0. Epub 2015 Aug 9.
Monahan M1, Boelaert K2, Jolly K3, Chan S4, Barton P1, Roberts TE5.

BACKGROUND: Results from previous studies show that the cognitive ability of offspring might be irreversibly damaged as a result of their mother's mild iodine deficiency during pregnancy. A reduced intelligence quotient (IQ) score has broad economic and societal cost implications because intelligence affects wellbeing, income, and education outcomes. Although pregnancy and lactation lead to increased iodine needs, no UK recommendations for iodine supplementation have been issued to pregnant women. We aimed to investigate the cost-effectiveness of iodine supplementation versus no supplementation for pregnant women in a mildly to moderately iodine-deficient population for which a population-based iodine supplementation programme-for example, universal salt iodisation-did not exist.

METHODS: We systematically searched MEDLINE, Embase, EconLit, and NHS EED for economic studies that linked IQ and income published in all languages until Aug 21, 2014. We took clinical data relating to iodine deficiency in pregnant women and the effect on IQ in their children aged 8-9 years from primary research. A decision tree was developed to compare the treatment strategies of iodine supplementation in tablet form with no iodine supplementation for pregnant women in the UK. Analyses were done from a health service perspective (analysis 1; taking direct health service costs into account) and societal perspective (analysis 2; taking education costs and the value of an IQ point itself into account), and presented in terms of cost (in sterling, relevant to 2013) per IQ point gained in the offspring. We made data-supported assumptions to complete these analyses, but used a conservative approach that limited the benefits of iodine supplementation and overestimated its potential harms.

FINDINGS: Our systematic search identified 1361 published articles, of which eight were assessed to calculate the monetary value of an IQ point. A discounted lifetime value of an additional IQ point based on earnings was estimated to be £3297 (study estimates range from £1319 to £11 967) for the offspring cohort. Iodine supplementation was cost saving from both a health service perspective (saving £199 per pregnant woman [sensitivity analysis range -£42 to £229]) and societal perspective (saving £4476 per pregnant woman [sensitivity analysis range £540 to £4495]), with a net gain of 1·22 IQ points in each analysis. Base case results were robust to sensitivity analyses.

INTERPRETATION: Iodine supplementation for pregnant women in the UK is potentially cost saving. This finding also has implications for the 1·88 billion people in the 32 countries with iodine deficiency worldwide. Valuation of IQ points should consider non-earnings benefits-eg, health benefits associated with a higher IQ not germane to earnings.

PMID: 26268911 Publisher wants $31 for the PDF


The Importance of Adequate Iodine during Pregnancy and Infancy - Zimmerman Dec 2016

Zimmerman
Iodine requirements are increased ≥50% during pregnancy. Iodine deficiency during pregnancy can cause maternal and fetal hypothyroidism and impair neurological development of the fetus. The consequences depend upon the timing and severity of the hypothyroidism; the most severe manifestation is cretinism. In iodine-deficient areas, controlled studies have demonstrated that iodine supplementation before or during early pregnancy eliminates new cases of cretinism, increases birth weight, reduces rates of perinatal and infant mortality and generally increases developmental scores in young children by 10-20%. Mild-to-moderate maternal iodine deficiency can cause thyroid dysfunction, but whether it impairs cognitive and/or neurological function in the offspring remains uncertain. In nearly all regions affected by iodine deficiency, salt iodization is the most cost-effective way of delivering iodine and improving maternal and infant health.

PMID: 27198746 DOI: 10.1159/000442078
Publisher rents PDF for $9.50


The effects of iodine deficiency in pregnancy and infancy.- Zimmerman 2012 full text

Paediatr Perinat Epidemiol. 2012 Jul;26 Suppl 1:108-17. doi: 10.1111/j.1365-3016.2012.01275.x.
Zimmermann MB1.

Iodine requirements are increased ≥ 50% during pregnancy. Iodine deficiency during pregnancy can cause maternal and fetal hypothyroidism and impair neurological development of the fetus. The consequences depend upon the timing and severity of the hypothyroidism; the most severe manifestation is cretinism.
In moderate-to-severely iodine-deficient areas, controlled studies have demonstrated that iodine supplementation before or during early pregnancy

  • eliminates new cases of cretinism,
  • increases birthweight,
  • reduces rates of perinatal and infant mortality and
  • generally increases developmental scores in young children by 10-20%.

Mild maternal iodine deficiency can cause thyroid dysfunction but whether it impairs cognitive and/or neurologic function in the offspring remains uncertain. Two meta-analyses have estimated that iodine-deficient populations experience a mean reduction in IQ of 12-13.5 points. In nearly all regions affected by iodine deficiency, salt iodisation is the most cost-effective way of delivering iodine and improving maternal and infant health.

 Download the PDF from VitaminDWiki


Iodine deficiency in pregnancy is prevalent in vulnerable groups in Denmark - Nov 2016

  • " The majority took iodine-containing supplements (86%)." but many were still deficient, PDF

Iodine Supplementation in Women During Preconception, Pregnancy, and Lactation: Dec 2016

Current Clinical Practice by U.S. Obstetricians and Midwives.
"One third of both obstetricians and midwives considered iodine status in U.S. pregnant women to be deficient."
Nice abstract, but PDF is behind a $51 paywall


Iodine Supplementation in Pregnancy and the Dilemma of Ambiguous Recommendations - March 2016

Eur Thyroid J. 2016 Mar;5(1):35-43. doi: 10.1159/000444254. Epub 2016 Mar 1.
Andersen SL1, Laurberg P2.

Iodine requirements are increased during pregnancy, predominantly caused by an increase in renal iodide clearance and in the use of iodine for thyroid hormone production. Because iodine deficiency (ID) in pregnancy may be associated with neurodevelopmental deficits in the offspring, a pertinent question is at what level of iodine intake pregnant women should be advised to take iodine-containing supplements. The consensus reached by the WHO/UNICEF/ICCIDD in 2007 was that pregnant women should not be recommended to take iodine-containing supplements if the population in general had been iodine sufficient for at least 2 years. However, guidance on this differs between scientific societies. This review discusses iodine supplementation in pregnancy. Based on current evidence, the recommendations given by WHO/UNICEF/ICCIDD in 2007 provide a valid guidance on the use of iodine supplements in pregnant women. Women living in a population with a median urinary iodine concentration (UIC) at or above 100 µg/l are not in need of iodine supplementation in pregnancy. On the other hand, if the population median UIC is below 100 µg/l, pregnant women should take iodine-containing supplements until the population in general has been iodine sufficient for at least 2 years by way of universal salt iodization.

PMID: 27099837 PMCID: PMC4836119 DOI: 10.1159/000444254
 Download the PDF from VitaminDWiki


Iodine supplementation in pregnancy - is it time? - July 2016

Clin Endocrinol (Oxf). 2016 Jul;85(1):10-4. doi: 10.1111/cen.13065. Epub 2016 Apr 6.
Taylor PN1, Vaidya B2.

Iodine is essential for the synthesis of thyroid hormone and optimal foetal neurological development. Pregnant women living in borderline or moderate-severe iodine deficient areas are at particularly high risk of being iodine deficient, and this may have important clinical consequences, particularly for the neurocognitive development of the offspring. It is a substantial problem and many countries including the United Kingdom are mild-moderately iodine deficient. Although the detrimental effects of severe iodine deficiency are well recognized, the benefits of correcting mild-to-moderate iodine deficiency are unclear due to a lack of randomized controlled trials in this area. However, observational data increasingly indicate that there may be substantial health and economic benefits from correcting iodine deficiency in pregnancy. There is now a growing trend from learned societies that iodine supplementation should be utilized in pregnancy in countries with mild-to-moderate iodine deficiency. The dose of iodine supplement needs to reflect local iodine status and iodization policies and will need careful monitoring at the population level to ensure doses to prevent under/excess dosing which would undermine the potential benefits. National tailored guidance is therefore essential.

PMID: 26998765 DOI: 10.1111/cen.13065


Maternal iodine insufficiency and adverse pregnancy outcomes - Oct 2016

Matern Child Nutr. 2016 Oct;12(4):680-7. doi: 10.1111/mcn.12211. Epub 2015 Sep 1.
Charoenratana C1, Leelapat P2, Traisrisilp K1, Tongsong T3.

This study aimed to assess the iodine status of pregnant women in each trimester and to compare the pregnancy outcomes between groups with iodine insufficiency and iodine sufficiency. Longitudinal study on urinary iodine concentration (UIC) in each trimester as well as comparison between women with iodine insufficiency (<150 mcg L(-1) ) and iodine sufficiency was conducted. Pregnant women without thyroid diseases who had not received iodine supplementation were recruited for UIC measurements in each trimester and were followed up for pregnancy outcomes. In the analysis of 384, 325 and 221 samples in the first, second and third trimester, the medians of UICs were 147.39, 157.01 and 153.07 mcg L(-1) , respectively. Of 399 women, 174 (43.6%) had a UIC less than 150 mcg L(-1) (suggesting iodine insufficiency) and 225 (56.4%) had a UIC greater than or equal to 150 mcg L(-1) (suggesting iodine sufficiency). Of 390 women with availability of the final outcomes, 171 and 219 in the insufficiency and sufficiency group, respectively,
the rates of preterm birth and low birthweight were significantly higher in the insufficiency group, 17.5% vs. 10.0% (P = 0.031) and 19.9% vs. 12.3% (P = 0.042), respectively.
Logistic regression analysis showed that iodine status was an independent risk of preterm birth and low birthweight. Finally, women with a UIC <100 mcg L(-1) had a significantly higher rate of fetal growth restriction, 13/68 vs. 30/322 (P = 0.031). In northern Thailand, a great number of pregnant women had a median UIC less than 150 mcg L(-1) and they had a higher risk of preterm birth and low birthweight. Finally, those with a median UIC of less than 100 mcg L(-1) had a higher risk of fetal growth restriction.

PMID: 26332721 DOI: 10.1111/mcn.12211


A review of 4 Iodine Tests - 2016?

Comparing 4 Different Methods Of Iodine Testing

I recently was consulting with a patient who saw a different holistic doctor, and this doctor recommended for her to take 25mg of iodine right off the bat, without any testing. I personally don’t recommend for anyone to begin taking high dosages of iodine unless if they have been tested for an iodine deficiency. But it’s amazing how many patients I have spoken with who are told to take iodine without having had any testing at all. Plus, even if someone is deficient in iodine, I personally recommend starting with a low dosage, rather than 25 to 50 mg immediately. I start most of my patients who are iodine deficient with 3mg and then gradually increase the dosage. For some people I start with a lower dosage than this. And of course some people I don’t recommend iodine to at all.

There are numerous ways to test for an iodine deficiency, and below I will discuss four different methods of iodine testing:

Iodine Testing Method #1: One sample urine test. This is the urine test typically performed by most medical doctors to determine the levels of iodine. While this isn’t a completely useless test, it isn’t as accurate as the iodine loading test, which is described below.

Iodine Testing Method #2: Blood test This seems to be an accurate way to test the iodine levels, but the problem is that most labs don’t do such testing.

Iodine Testing Method #3: Iodine Patch Test. This is a general test which can help determine whether someone is deficient in iodine. It involves drawing a 2 x 2 patch on your forearm using a 2% tincture of iodine. For someone who isn’t iodine deficient, the patch shouldn’t begin to fade until after 24 hours. Someone who is deficient in iodine will see the patch disappear in a shorter amount of time. Those with a severe iodine deficiency will see the patch begin to fade or disappear completely in 12 hours or less.

Once again, this isn’t the most accurate test (although it definitely is the least expensive of the four). Even though it isn’t accurate, it can help to give a general idea as to whether someone is deficient in iodine, and if they will need to supplement with iodine. However, I think 24 hours is a random number, and I feel that 12 to 14 hours is more accurate in determining how long the iodine should last before fading significantly. While someone can start off with this test, eventually it is recommended that they receive an iodine loading test to get a more specific reading.

Iodine Testing Method #4: Iodine Loading Test. This test measures the excretion of iodine over a 24-hour period. It admittedly isn’t the most convenient test, as you need to collect EVERY urine sample within a 24-hour period. Before this test you need to take a 50 mg tablet of iodine. Although taking such a high dosage on a regular basis without prior testing isn’t recommended, taking it one time shouldn’t cause problems with most people. This usually includes people with Hashimoto’s Thyroiditis. However, many people with Hashimoto’s Thyroiditis are still cautious about taking this test due to the ingestion of iodine, which is fine, as they can always choose one of the other tests if they’re really concerned about any negative effects of taking the iodine.

Ideally someone who has a sufficient amount of iodine should excrete at least 90% of the iodine over a 24-hour period. If it is less than this then the person has an iodine deficiency. The lower the excretion rate, the greater the iodine deficiency.

How Much Iodine Should One Take?
If it’s determined that someone is iodine deficient, then how much iodine should that person take? There are different opinions regarding this, but as I mentioned earlier, what I do is put someone on a low dosage of iodine (3mg), and then gradually increase the dosage each week, and will eventually retest. If the person begins with an iodine patch test, they of course can easily retest every 2 to 4 weeks, although one needs to keep in mind that it usually takes at least a few months to correct such a deficiency, and for someone with a moderate to a severe deficiency it can take a long time to accomplish this. For those who don’t obtain an Iodine Loading test right away, I definitely recommend obtaining this test after three to six months after beginning to supplement with iodine.

Different doctors will of course have different approaches, as some will recommend starting with large dosages of iodine, and others like myself will suggest taking it slowly. While many people have no problem taking large dosages of iodine immediately, others are not able to tolerate larger dosages. And there really is no way to predict how someone will respond, which is why I like to play it safe and start someone with a lower dosage.

In summary, before anyone supplements with iodine I recommend for them to obtain at least one of the above tests I mentioned. I also recommend that people begin with a low dosage of iodine, and then gradually increase the dosage. And when someone does begin an iodine supplementation program, it is important to retest after a few months in order to make sure they are taking a sufficient amount of iodine on a daily basis.

90% of pregnant women in Turkey did not have enough Iodine – even with salt Iodization – 2016

Iodine status of pregnant women in a metropolitan city which proved to be an iodine-sufficient area. Is mandatory salt iodisation enough for pregnant women?
Gynecol Endocrinol. 2016;32(3):188-92. doi: 10.3109/09513590.2015.1101443. Epub 2015 Oct 22.
Oral E1, Aydogan Mathyk B2, Aydogan BI3, Acıkgoz AS1, Erenel H2, Celik Acıoglu H4, Anık Ilhan G5, Dane B6, Ozel A6, Tandogan B7, Cakar E7, Isci H8, Kayan B8, Aslan H9, Ekiz A9, Sancak S10, Celik A11, Yoldemir T5, Uzun O5, Erdogan MF3.

The objective of this study was to assess the iodine status of pregnant women in a metropolitan city which was stated as iodine sufficient area after salt iodination program. This multicenter, cross-sectional study was carried out on 3543 pregnant women. Age, gestational weeks, smoking, consumption of iodized salt, dietary salt restriction, history of stillbirth, abortus and congenital malformations were questioned. Spot urine samples were analyzed for urine iodine concentration (UIC). The outcomes were: (a) median UIC in three trimesters of pregnancy and (b) frequency of ID among pregnant women. The median UIC was 73 µg/L. The median UIC was 77 µg/L (1-324), 73 µg/L (1-600) and 70 µg/L (1-1650) in three trimesters of pregnancy, respectively (p: 0.14). UIC <50 µg/L was observed in 36.6% (n: 1295) and UIC<150 µg/L was observed in 90.7% (n: 3214) of pregnant women. Only 1% (n: 34) of the pregnant women had UIC levels higher than 500 µg/L. This study showed that more than 90% of the pregnant women in this iodine-sufficient city are facing some degree of iodine deficiency during their pregnancy. A salt iodization program might be satisfactory for the non-pregnant population, but it seems to be insufficient for the pregnant population.

PMID: 26489983 DOI: 10.3109/09513590.2015.1101443 Behind $54 paywall


Getting enough Iodine during pregnancy increases IQ and decreased deaths – 2012

The effects of iodine deficiency in pregnancy and infancy.
Paediatr Perinat Epidemiol. 2012 Jul;26 Suppl 1:108-17. doi: 10.1111/j.1365-3016.2012.01275.x.
Zimmermann MB Laboratory for Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland. michael.zimmermann at hest.ethz.ch

Iodine requirements are increased ≥ 50% during pregnancy. Iodine deficiency during pregnancy can cause maternal and fetal hypothyroidism and impair neurological development of the fetus. The consequences depend upon the timing and severity of the hypothyroidism; the most severe manifestation is cretinism. In moderate-to-severely iodine-deficient areas, controlled studies have demonstrated that iodine supplementation before or during early pregnancy eliminates new cases of cretinism, increases birthweight, reduces rates of perinatal and infant mortality and generally increases developmental scores in young children by 10-20%. Mild maternal iodine deficiency can cause thyroid dysfunction but whether it impairs cognitive and/or neurologic function in the offspring remains uncertain.
Two meta-analyses have estimated that iodine-deficient populations experience a mean reduction in IQ of 12-13.5 points. In nearly all regions affected by iodine deficiency, salt iodisation is the most cost-effective way of delivering iodine and improving maternal and infant health.
© 2012 Blackwell Publishing Ltd.

PMID: 22742605 DOI: 10.1111/j.1365-3016.2012.01275.x
 Download the PDF from VitaminDWiki


Less than 150 ug/L of Iodine during pregnancy resulted in poor school performance – 2013

Mild iodine deficiency during pregnancy is associated with reduced educational outcomes in the offspring: 9-year follow-up of the gestational iodine cohort.
J Clin Endocrinol Metab. 2013 May;98(5):1954-62. doi: 10.1210/jc.2012-4249. Epub 2013 Apr 30.
Hynes KL1, Otahal P, Hay I, Burgess JR.
1Menzies Research Institute Tasmania, University of Tasmania, Sandy Bay, Tasmania 7005, Australia. k.l.hynes at utas.edu.au

CONTEXT:
Severe iodine deficiency (ID) during gestation is associated with neurocognitive sequelae. The long-term impact of mild ID, however, has not been well characterized.
OBJECTIVE:
The purpose of this study was to determine whether children born to mothers with urinary iodine concentrations (UICs) <150 μg/L during pregnancy have poorer educational outcomes in primary school than peers whose mothers did not have gestational ID (UIC ≥150 μg/L).
DESIGN:
This was a longitudinal follow-up (at 9 years old) of the Gestational Iodine Cohort. Pregnancy occurred during a period of mild ID in the population, with the children subsequently growing up in an iodine-replete environment.
SETTING AND PARTICIPANTS:
Participants were children whose mothers attended The Royal Hobart Hospital (Tasmania) antenatal clinics between 1999 and 2001.
MAIN OUTCOME MEASURES:
Australian national curriculum and Tasmanian state curriculum educational assessment data for children in year 3 were analyzed.
RESULTS:
Children whose mothers had UIC <150 μg/L had reductions of

  • 10.0% in spelling (-41.1 points, 95% confidence interval CI, -68.0 to -14.3, P = .003),
  • 7.6% in grammar (-30.9 points, 95% CI, -60.2 to -1.7, P = .038), and
  • 5.7% in English-literacy (-0.33 points, 95% CI, -0.63 to -0.03, P = .034)

performance compared with children whose mothers' UICs were ≥150 μg/L.
These associations remained significant after adjustment for a range of biological factors (maternal age at birth of child, gestational length at time of birth, gestational age at time of urinary iodine collection, birth weight, and sex). Differences in spelling remained significant after further adjustment for socioeconomic factors (maternal occupation and education).
CONCLUSIONS:
This study provides preliminary evidence that even mild iodine deficiency during pregnancy can have long-term adverse impacts on fetal neurocognition that are not ameliorated by iodine sufficiency during childhood.

 Download the PDF from VitaminDWiki

PMID: 23633204 DOI: 10.1210/jc.2012-4249


Iodine supplementation cost effective during pregnancy in UK and probably 32 other countries –2015

Costs and benefits of iodine supplementation for pregnant women in a mildly to moderately iodine-deficient population: a modelling analysis.
Lancet Diabetes Endocrinol. 2015 Sep;3(9):715-22. doi: 10.1016/S2213-8587(15)00212-0. Epub 2015 Aug 9.
Monahan M1, Boelaert K2, Jolly K3, Chan S4, Barton P1, Roberts TE5.

  • 1 Department of Health Economics, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
  • 2 School of Health and Population Sciences and Centre for Endocrinology, Diabetes and Metabolism, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
  • 3 Department of Public Health, Epidemiology, and Biostatistics, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
  • 4 Department of Obstetrics & Gynaecology, Yoo Loo Lin School of Medicine, National University of Singapore, Singapore.
  • 5 Department of Health Economics, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK. Electronic address: t.e.roberts at bham.ac.uk.

BACKGROUND:
Results from previous studies show that the cognitive ability of offspring might be irreversibly damaged as a result of their mother's mild iodine deficiency during pregnancy. A reduced intelligence quotient (IQ) score has broad economic and societal cost implications because intelligence affects wellbeing, income, and education outcomes. Although pregnancy and lactation lead to increased iodine needs, no UK recommendations for iodine supplementation have been issued to pregnant women. We aimed to investigate the cost-effectiveness of iodine supplementation versus no supplementation for pregnant women in a mildly to moderately iodine-deficient population for which a population-based iodine supplementation programme- -for example, universal salt iodisation- -did not exist.
METHODS:
We systematically searched MEDLINE, Embase, EconLit, and NHS EED for economic studies that linked IQ and income published in all languages until Aug 21, 2014. We took clinical data relating to iodine deficiency in pregnant women and the effect on IQ in their children aged 8-9 years from primary research. A decision tree was developed to compare the treatment strategies of iodine supplementation in tablet form with no iodine supplementation for pregnant women in the UK. Analyses were done from a health service perspective (analysis 1; taking direct health service costs into account) and societal perspective (analysis 2; taking education costs and the value of an IQ point itself into account), and presented in terms of cost (in sterling, relevant to 2013) per IQ point gained in the offspring. We made data-supported assumptions to complete these analyses, but used a conservative approach that limited the benefits of iodine supplementation and overestimated its potential harms.
FINDINGS:
Our systematic search identified 1361 published articles, of which eight were assessed to calculate the monetary value of an IQ point. A discounted lifetime value of an additional IQ point based on earnings was estimated to be £3297 (study estimates range from £1319 to £11,967) for the offspring cohort. Iodine supplementation was cost saving from both a health service perspective (saving £199 per pregnant woman [sensitivity analysis range -£42 to £229]) and societal perspective (saving £4476 per pregnant woman [sensitivity analysis range £540 to £4495]), with a net gain of 1·22 IQ points in each analysis. Base case results were robust to sensitivity analyses.
INTERPRETATION:
Iodine supplementation for pregnant women in the UK is potentially cost saving. This finding also has implications for the 1·88 billion people in the 32 countries with iodine deficiency worldwide. Valuation of IQ points should consider non-earnings benefits- -eg, health benefits associated with a higher IQ not germane to earnings.

PMID: 26268911 DOI: 10.1016/S2213-8587(15)00212-0 PDF is behind $31.50 paywall


Only 12% of UK pregnant women knew of the Iodine recommendations – 2015

Iodine and pregnancy - a UK cross-sectional survey of dietary intake, knowledge and awareness.
Br J Nutr. 2015 Jul 14;114(1):108-17. doi: 10.1017/S0007114515001464. Epub 2015 May 26.
Combet E1, Bouga M1, Pan B1, Lean ME1, Christopher CO1.
1Department of Human Nutrition,School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow,New Lister Building, Alexandra Parade,GlasgowG31 2ER,UK.

Iodine is a key component of the thyroid hormones, which are critical for healthy growth, development and metabolism. The UK population is now classified as mildly iodine-insufficient. Adequate levels of iodine during pregnancy are essential for fetal neurodevelopment, and mild iodine deficiency is linked to developmental impairments. In the absence of prophylaxis in the UK, awareness of nutritional recommendations during pregnancy would empower mothers to make the right dietary choices leading to adequate iodine intake. The present study aimed to: estimate mothers' dietary iodine intake in pregnancy (using a FFQ); assess awareness of the importance of iodine in pregnancy with an understanding of existing pregnancy dietary and lifestyle recommendations with relevance for iodine; examine the level of confidence in meeting adequate iodine intake. A cross-sectional survey was conducted and questionnaires were distributed between August 2011 and February 2012 on local (Glasgow) and national levels (online electronic questionnaire); 1026 women, UK-resident and pregnant or mother to a child aged up to 36 months participated in the study. While self-reported awareness about general nutritional recommendations during pregnancy was high (96 %), awareness of iodine-specific recommendations was very low (12 %), as well as the level of confidence of how to achieve adequate iodine intake (28 %). Median pregnancy iodine intake, without supplements, calculated from the FFQ, was 190 μg/d (interquartile range 144-256μg/d), which was lower than that of the WHO's recommended intake for pregnant women (250 μg/d). Current dietary recommendations in pregnancy, and their dissemination, are found not to equip women to meet the requirements for iodine intake.

PMID: 26005740 DOI: 10.1017/S0007114515001464

 Download the PDF from VitaminDWiki


Need 150 ug of iodine daily during Pregnancy (much less than RDA) – Consensus of 6 organizations – 2014

AAP Recommendations on Iodine Nutrition During Pregnancy and Lactation
Pediatrics, October 2014, VOLUME 134 / ISSUE 4
AAP Recommendations on Iodine Nutrition During Pregnancy and Lactation
Angela M. Leung, Elizabeth N. Pearce, Lewis E. Braverman, Alex Stagnaro-Green

Adequate iodine is crucial for thyroid hormone production, which is required for normal neurodevelopment during pregnancy and early childhood. Women who are pregnant and lactating require increased iodine intake. Unfortunately, median iodine levels in the United States have decreased by 50% in the past 3 decades, with recent studies demonstrating that pregnant women are mildly iodine deficient. Nevertheless, data from the NHANES 1999–2006 showed that only 22% of US pregnant women take an iodine-containing dietary supplement.1 Even mild iodine deficiency has been associated with adverse effects. A recent study from the United Kingdom demonstrated significantly decreased IQ scores in children whose mothers were mildly iodine deficient during pregnancy.2

We therefore applaud the American Academy of Pediatrics (AAP) for focusing on the issue of iodine sufficiency during pregnancy and breastfeeding.3 Nevertheless, we believe that the AAP position would benefit from the following modifications, which would then be consistent with previous recommendations from the

  • American Thyroid Association,4
  • Endocrine Society,
  • Teratology Society,
  • American Association of Clinical Endocrinologists, and the
  • International Council for the Control of Iodine Deficiency Disorders Global Network:


The AAP statement does not make a clear recommendation for iodine supplementation during pregnancy. The organizations above recommend that all pregnant US women take a prenatal vitamin that contains 150 mcg iodine daily in the form of potassium iodide.

The AAP statement recommends that breastfeeding women ingest a supplement with at least 150 mcg of iodine daily. The organizations mentioned recommend that breastfeeding women take a prenatal vitamin that contains 150 mcg of iodine. Taking an excess of iodine (>1100 mcg daily) can result in iodine-induced thyroid dysfunction and should be avoided.5

The AAP recommends that urinary iodine testing be considered in at risk individuals. Urinary iodine concentrations can be used to determine the dietary iodine status of populations, but because of substantial day-to-day and hour-to-hour variation in urinary iodine excretion, urinary iodine concentrations cannot be used to determine the iodine status of an individual patient.

In conclusion, the recent statement by the AAP helps to maintain focus on the importance of iodine sufficiency during pregnancy and lactation—an issue that directly affects the health and neurocognitive development of our children. We encourage the AAP to evaluate the issues raised in our letter and look forward to working collaboratively to make iodine deficiency in the United States an issue of the past.

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More studies needed for Iodine during pregnancy: 2014 then 2016

Consequences of iodine deficiency and excess in pregnant women: an overview of current knowns and unknowns
Am J Clin Nutr 2016 104: Supplement 3 918S-923S; First published online August 17, 2016.
Elizabeth N Pearce3, elizabeth.pearce at bmc.org , John H Lazarus4, Rodrigo Moreno-Reyes5, and Michael B Zimmermann6
3Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, MA;
4Thyroid Research Group, Institute of Molecular and Experimental Medicine, Cardiff University, University Hospital of Wales, Cardiff, United Kingdom;
5Department of Nuclear Medicine, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium; and
6Human Nutrition Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland

  • Presented at the workshop “Maternal Iodine Supplementation: Clinical Trials and Assessment of Outcomes” held by the NIH Office of Dietary Supplements in Rockville, MD, 22–23 September 2014.
  • Supported in part by the Iodine Global Network, Ottawa, Canada.

Severe iodine deficiency during development results in maternal and fetal hypothyroidism and associated serious adverse health effects, including cretinism and growth retardation. Universal salt iodization is the first-line strategy for the elimination of severe iodine deficiency. Iodine supplementation is recommended for vulnerable groups in severely iodine-deficient regions where salt iodization is infeasible or insufficient. A recent clinical trial has informed best practices for iodine supplementation of severely iodine-deficient lactating mothers. Because of successful programs of universal salt iodization in formerly severely iodine-deficient regions around the world, public health concern has shifted toward mild to moderate iodine deficiency, which remains prevalent in many regions, especially among pregnant women. Observational studies have shown associations between both mild maternal iodine deficiency and mild maternal thyroid hypofunction and decreased child cognition. Iodine supplementation has been shown to improve indexes of maternal thyroid function, even in marginally iodine-deficient areas. However, no data are yet available from randomized controlled trials in regions of mild to moderate iodine insufficiency on the relation between maternal iodine supplementation and neurobehavioral development in the offspring; thus, the long-term benefits and safety of such supplementation are uncertain. Although it is clear that excessive iodine intake can cause alterations in thyroid function in susceptible individuals, safe upper limits for iodine intake in pregnancy have not been well defined. Well-designed, prospective, randomized controlled trials that examine the effects of iodine supplementation on maternal thyroid function and infant neurobehavioral development in mildly to moderately iodine-deficient pregnant women are urgently needed. In addition, clinical data on the effects of iodine excess in pregnant and lactating women are needed to inform current recommendations for safe upper limits on chronic iodine ingestion in general and on iodine supplementation in particular.

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Attached files

ID Name Comment Uploaded Size Downloads
7944 Iodine Supplementation in Pregnancy and the Dilemma of Ambiguous Recommendations.pdf PDF 2016 admin 27 Apr, 2017 01:02 249.33 Kb 38
7943 Zimmermann-2012-Paediatric_and_Perinatal_Epidemiology.pdf PDF admin 27 Apr, 2017 00:53 122.25 Kb 41
7719 AAP Iodine recommendations.pdf PDF admin 26 Jan, 2017 22:48 587.90 Kb 56
7718 UK knowledge.pdf PDF admin 26 Jan, 2017 22:47 311.35 Kb 21
7717 9-Year Follow-up.pdf PDF admin 26 Jan, 2017 22:47 153.46 Kb 26
7716 The Effects of Iodine Deficiency in Pregnancy and Infancy - 2012.pdf admin 26 Jan, 2017 22:46 122.25 Kb 13
7715 Zimmermann-2012-Paediatric_and_Perinatal_Epidemiology.pdf PDF admin 26 Jan, 2017 22:46 122.25 Kb 25
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