Dietary Iodine in Pregnant Women from the Boston, Massachusetts Area

Pearce, Elizabeth N.; Bazrafshan, Hamidreza; He, Xuemei; Pino, Sam; Braverman, Lewis E.

doi:10.1089/105072504323031013

Cited by 56 publications

(30 citation statements)

References 2 publications

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“…A limitation of the present study is that urine samples were not available for iodine measurements. However, we recently reported that low urinary iodine values (less than 50 μg/L) were present in 9 out of 100 pregnant Boston-area women sampled (31). Relatively few of the women in this study were taking multivitamins that contained iodine.…”

Section: Discussionmentioning

confidence: 54%

Association of First-Trimester Thyroid Function Test Values with Thyroperoxidase Antibody Status, Smoking, and Multivitamin Use

Pearce

Oken

Gillman³

et al. 2008

Endocrine Practice

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125

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Objective: To determine first-trimester thyroid function values and associations with thyroperoxidase antibody (TPO-Ab) status, smoking, emesis, and iodine-containing multivitamin use. Methods:We collected information by interview, questionnaire, and blood draw at the initial obstetric visit in 668 pregnant women without known thyroid disease. We compared thyroidstimulating hormone (TSH), total thyroxine (T 4 ), and free T 4 index (FT 4 I) values by TPO-Ab status. Multiple regression was used to identify characteristics associated with thyroid function values. Results:The following median (range containing 95% of the data points) thyroid function test values were obtained in 585 TPO-Ab-negative women: TSH, 1.1 mIU/L (0.04-3.6); FT 4 I, 2.1 (1.5-2.9); and T 4 , 9.9 μg/dL (7.0-14.0). The following median (range containing 95% of the data points) thyroid function test values were obtained in 83 TPO-Ab-positive women: TSH, 1.8 mIU/L (0.3-6.4) (P<.001); FT 4 I, 2.0 (1.4-2.7) (P = .06); and T 4 , 9.3 μg/dL (6.8-13.0) (P = .03) (P values denote statistically significant differences between TPO-Ab-positive and negative participants). Among TPO-Ab-negative participants, TSH level was not associated with use of iodine-containing multivitamins, smoking, or race. TSH increased 0.03 mIU/L for every year of maternal age (P = . 03) and decreased by 0.3 mIU/L for every increase in parity (P<.001). T 4 decreased 0.04 μg/dL for every year of maternal age (P = .04). Mean FT 4 I was 2.05 in smokers and 2.20 in nonsmokers (P<. 01). There were no relationships between T 4 or FT 4 I and parity, race, or iodine-containing multivitamin use. Conclusion:TPO-Ab status of pregnant women should be considered when constructing trimesterspecific reference ranges because elevated serum TPO-Ab levels are associated with higher TSH and lower T 4 values.

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Section: Discussionmentioning

confidence: 54%

Association of First-Trimester Thyroid Function Test Values with Thyroperoxidase Antibody Status, Smoking, and Multivitamin Use

Pearce

Oken

Gillman³

et al. 2008

Endocrine Practice

Self Cite

125

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“…Based on UI evaluation, U.S. women of childbearing age may already be borderline iodine-deficient (23). Extensive data show that for U.S. women with UI <100 µg/L, perchlorate in urine, reflective of intake, was a significant negative predictor of thyroxine (p < 0.0001) and a positive predictor of TSH (p ) 0.001) (103).…”

Section: Iodine In Freshly Opened Containers Of Us Iodized Saltmentioning

confidence: 99%

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Dasgupta,

Liu,

Dyke

2008

Environ. Sci. Technol.

112

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Adequacy of iodine nutrition in the United States has lately been of concern. A major source of dietary iodine for the U.S. population is iodized salt. The U.S. Food and Drug Administration (USFDA) recommends 60-100 mg KI/kg salt, equivalent to 46-76 mg I/kg salt. All U.S. iodized salt contains 45 mg I/kg according to labels. We collected samples of table salt from freshly opened containers from U.S. volunteers. A sample was sent to us when the can was first purchased. Subsets of volunteers sent further samples when the salt container became halfempty through normal use and a further final sample when the container was nearly finished. We also looked at iodine distribution homogeneity within individual containers, loss of iodine from salt upon exposure to humidity and sunlight, and upon short-term heating (dry and in solution) as may be encountered in cooking. Measurements were made in 0.01% w/v salt solutions by induction coupled plasma-mass spectrometry with 72 Ge as an internal standard. The median and mean ((sd) I content in freshly opened top-of-the-can salt samples was 44.1 and 47.5 ( 18.5 mg/kg (n ) 88, range 12.7-129 mg I/kg) and geometric mean and standard deviation of 44.70 and 1.41. Fortyseven of 88 samples fell below the USFDA recommended I content while 6 exceeded it. The homogeneity in a single can of salt varied greatly: in 5 samples taken from the same container from different depths, the iodine content varied by as little as 1.2× (8.3% coefficient of variance (CV)) to as much as 3.3× (49.3% CV) from one container/brand to another. Iodine is significantly lost upon high humidity storage but light or dry heat has little effect. There is much recent literature on iodine sufficiency and uptake inhibitors; there is also much misinformation and disinformation. We review the relevant literature and discuss our results with reference to the United States.

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“…In Poland, where iodization of household salt became obligatory in 1997, only 37% of the pregnant women had urinary iodine concentrations above 150 mg=L (27). Both a study performed in Boston, where 9% of pregnant women had urinary iodine concentrations below 50 mg=L (28), and a report of the National Health and Nutrition Examination Surveys (NHANES III) (29) have pointed out that urinary iodine is well below the values recommended by the World Health Organization and the International Council for Control of Iodine Deficiency Disorders (28)(29)(30). To prevent iodine deficiency, the American Thyroid Association (31) promoted iodine supplementation for pregnancy and lactation in the United States and Canada, recommending supplements of 150 mg iodine per day, this being the maximum permitted in nutritional supplements for pregnancy dispensed over-the-counter.…”

mentioning

confidence: 99%

Delayed Neurobehavioral Development in Children Born to Pregnant Women with Mild Hypothyroxinemia During the First Month of Gestation: The Importance of Early Iodine Supplementation

Berbel

Mestre

Santamaría

et al. 2009

Thyroid

334

243

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Background: Maternal hypothyroxinemia, due to gestational iodine deficiency, causes neurological dysfunctions in the progeny. Our aim was to determine the effects of delayed iodine supplementation (200 mg KI per day) to mildly hypothyroxinemic pregnant women at the beginning of gestation (i.e., having circulating free thyroxine [FT 4 ] within the 0th-10th percentile interval and normal thyrotropin [TSH]) on the neurobehavioral development of their children. Methods: Using the Brunet-Lézine scale, we evaluated the neurocognitive performance at 18 months of age in three groups of children. Group 1 included children of women with FT 4 above the 20th percentile at 4-6 gestational weeks and at full-term. Group 2 included children of mildly hypothyroxinemic women diagnosed during the first 12-14 gestational weeks and with FT 4 above the 20th percentile at full-term. Group 3 included children born to mildly hypothyroxinemic women at full-term, without iodine supplementation during gestation. Women of all groups were iodine supplemented from the day of enrollment until the end of lactation. Results: Before iodine supplementation, 33.0% of the women (114 out of 345) were hypothyroxinemic, with FT 4 below normal in 28 of them (8.1%). None were found to be hypothyroxinemic at full-term after supplementation. The mean (AESD) developmental quotient of children was 101.8 AE 9.7 in group 1 (n ¼ 13) vs. 87.5 AE 8.9 in group 3 (n ¼ 19; p < 0.001) and 92.2 AE 5.4 in group 2 (n ¼ 12; p < 0.05). The difference between groups 2 and 3 was not statistically significant. Delayed neurobehavioral performance was observed in 36.8% and 25.0% of children in groups 3 and 2, respectively, compared with no children in group 1. Differences ( p < 0.001) were found on gross and fine motor coordination and socialization quotients. No statistically significant differences were found on language quotients. Conclusions: A delay of 6-10 weeks in iodine supplementation of hypothyroxinemic mothers at the beginning of gestation increases the risk of neurodevelopmental delay in the progeny. Public health programs should address the growing problem of iodine deficiency among women of gestational age in developing and industrialized nations.

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Dietary Iodine in Pregnant Women from the Boston, Massachusetts Area

Cited by 56 publications

References 2 publications

Association of First-Trimester Thyroid Function Test Values with Thyroperoxidase Antibody Status, Smoking, and Multivitamin Use

Association of First-Trimester Thyroid Function Test Values with Thyroperoxidase Antibody Status, Smoking, and Multivitamin Use

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

Delayed Neurobehavioral Development in Children Born to Pregnant Women with Mild Hypothyroxinemia During the First Month of Gestation: The Importance of Early Iodine Supplementation

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