Iron deficiency predicts poor maternal thyroid status during pregnancy

M.B. Zimmermann, H. Burgi, R.F. Hurrell

Research output: Contribution to journalArticleAcademicpeer-review

57 Citations (Scopus)

Abstract

Context: Pregnant women are often iron deficient, and iron deficiency has adverse effects on thyroid metabolism. Impaired maternal thyroid function during pregnancy may cause neurodevelopmental delays in the offspring. Objective: Our objective was to investigate whether maternal iron status is a determinant of TSH and/or total T-4 ( TT4) concentrations during pregnancy. Design and Outcome Measures: In a representative national sample of Swiss pregnant women ( n = 365) in the second and third trimester, samples of urine and blood were collected, and data on maternal characteristics and supplement use were recorded. Concentrations of TSH, TT4, hemoglobin, mean corpuscular volume, serum ferritin, transferrin receptor, and urinary iodine were measured. Body iron stores were calculated and stepwise regressions performed to look for associations. Results: Median urinary iodine was 139 mu g/liter ( range 30 - 433). In the third trimester, nearly 40% of women had negative body iron stores, 16% had a TT4 less than 100 nmol/liter, and 6% had a TSH more than 4.0 mU/liter. Compared with the women with positive body iron stores, the relative risk of a TT4 less than 100 nmol/liter in the group with negative body iron stores was 7.8 ( 95% confidence interval 4.1; 14.9). Of the 12 women with TSH more than 4.0 mU/liter, 10 had negative body iron stores. Serum ferritin, transferrin receptor, and body iron stores were highly significant predictors of TSH ( standardized beta: -0.506, 0.602, and - 0.589, respectively; all P <0.0001) and TT4 ( standardized beta: 0.679, - 0.589, and 0.659, respectively; all P <0.0001). Conclusion: Poor maternal iron status predicts both higher TSH and lower TT4 concentrations during pregnancy in an area of borderline iodine deficiency.
Original languageEnglish
Pages (from-to)3436-3440
JournalJournal of Clinical Endocrinology and Metabolism
Volume92
Issue number9
DOIs
Publication statusPublished - 2007

Fingerprint

Thyroid Gland
Iron
Mothers
Pregnancy
Iodine
Transferrin Receptors
Third Pregnancy Trimester
Ferritins
Pregnant Women
Beta Subunit Thyrotropin
Erythrocyte Indices
Second Pregnancy Trimester
Serum
Metabolism
Hemoglobins
Blood
Outcome Assessment (Health Care)
Urine
Confidence Intervals

Keywords

  • iodine supplementation
  • subclinical hypothyroidism
  • goitrous children
  • cote-divoire
  • body iron
  • anemia
  • women
  • recommendations
  • salt
  • rats

Cite this

Zimmermann, M.B. ; Burgi, H. ; Hurrell, R.F. / Iron deficiency predicts poor maternal thyroid status during pregnancy. In: Journal of Clinical Endocrinology and Metabolism. 2007 ; Vol. 92, No. 9. pp. 3436-3440.
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abstract = "Context: Pregnant women are often iron deficient, and iron deficiency has adverse effects on thyroid metabolism. Impaired maternal thyroid function during pregnancy may cause neurodevelopmental delays in the offspring. Objective: Our objective was to investigate whether maternal iron status is a determinant of TSH and/or total T-4 ( TT4) concentrations during pregnancy. Design and Outcome Measures: In a representative national sample of Swiss pregnant women ( n = 365) in the second and third trimester, samples of urine and blood were collected, and data on maternal characteristics and supplement use were recorded. Concentrations of TSH, TT4, hemoglobin, mean corpuscular volume, serum ferritin, transferrin receptor, and urinary iodine were measured. Body iron stores were calculated and stepwise regressions performed to look for associations. Results: Median urinary iodine was 139 mu g/liter ( range 30 - 433). In the third trimester, nearly 40{\%} of women had negative body iron stores, 16{\%} had a TT4 less than 100 nmol/liter, and 6{\%} had a TSH more than 4.0 mU/liter. Compared with the women with positive body iron stores, the relative risk of a TT4 less than 100 nmol/liter in the group with negative body iron stores was 7.8 ( 95{\%} confidence interval 4.1; 14.9). Of the 12 women with TSH more than 4.0 mU/liter, 10 had negative body iron stores. Serum ferritin, transferrin receptor, and body iron stores were highly significant predictors of TSH ( standardized beta: -0.506, 0.602, and - 0.589, respectively; all P <0.0001) and TT4 ( standardized beta: 0.679, - 0.589, and 0.659, respectively; all P <0.0001). Conclusion: Poor maternal iron status predicts both higher TSH and lower TT4 concentrations during pregnancy in an area of borderline iodine deficiency.",
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Iron deficiency predicts poor maternal thyroid status during pregnancy. / Zimmermann, M.B.; Burgi, H.; Hurrell, R.F.

In: Journal of Clinical Endocrinology and Metabolism, Vol. 92, No. 9, 2007, p. 3436-3440.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Iron deficiency predicts poor maternal thyroid status during pregnancy

AU - Zimmermann, M.B.

AU - Burgi, H.

AU - Hurrell, R.F.

N1 - 000249279800015

PY - 2007

Y1 - 2007

N2 - Context: Pregnant women are often iron deficient, and iron deficiency has adverse effects on thyroid metabolism. Impaired maternal thyroid function during pregnancy may cause neurodevelopmental delays in the offspring. Objective: Our objective was to investigate whether maternal iron status is a determinant of TSH and/or total T-4 ( TT4) concentrations during pregnancy. Design and Outcome Measures: In a representative national sample of Swiss pregnant women ( n = 365) in the second and third trimester, samples of urine and blood were collected, and data on maternal characteristics and supplement use were recorded. Concentrations of TSH, TT4, hemoglobin, mean corpuscular volume, serum ferritin, transferrin receptor, and urinary iodine were measured. Body iron stores were calculated and stepwise regressions performed to look for associations. Results: Median urinary iodine was 139 mu g/liter ( range 30 - 433). In the third trimester, nearly 40% of women had negative body iron stores, 16% had a TT4 less than 100 nmol/liter, and 6% had a TSH more than 4.0 mU/liter. Compared with the women with positive body iron stores, the relative risk of a TT4 less than 100 nmol/liter in the group with negative body iron stores was 7.8 ( 95% confidence interval 4.1; 14.9). Of the 12 women with TSH more than 4.0 mU/liter, 10 had negative body iron stores. Serum ferritin, transferrin receptor, and body iron stores were highly significant predictors of TSH ( standardized beta: -0.506, 0.602, and - 0.589, respectively; all P <0.0001) and TT4 ( standardized beta: 0.679, - 0.589, and 0.659, respectively; all P <0.0001). Conclusion: Poor maternal iron status predicts both higher TSH and lower TT4 concentrations during pregnancy in an area of borderline iodine deficiency.

AB - Context: Pregnant women are often iron deficient, and iron deficiency has adverse effects on thyroid metabolism. Impaired maternal thyroid function during pregnancy may cause neurodevelopmental delays in the offspring. Objective: Our objective was to investigate whether maternal iron status is a determinant of TSH and/or total T-4 ( TT4) concentrations during pregnancy. Design and Outcome Measures: In a representative national sample of Swiss pregnant women ( n = 365) in the second and third trimester, samples of urine and blood were collected, and data on maternal characteristics and supplement use were recorded. Concentrations of TSH, TT4, hemoglobin, mean corpuscular volume, serum ferritin, transferrin receptor, and urinary iodine were measured. Body iron stores were calculated and stepwise regressions performed to look for associations. Results: Median urinary iodine was 139 mu g/liter ( range 30 - 433). In the third trimester, nearly 40% of women had negative body iron stores, 16% had a TT4 less than 100 nmol/liter, and 6% had a TSH more than 4.0 mU/liter. Compared with the women with positive body iron stores, the relative risk of a TT4 less than 100 nmol/liter in the group with negative body iron stores was 7.8 ( 95% confidence interval 4.1; 14.9). Of the 12 women with TSH more than 4.0 mU/liter, 10 had negative body iron stores. Serum ferritin, transferrin receptor, and body iron stores were highly significant predictors of TSH ( standardized beta: -0.506, 0.602, and - 0.589, respectively; all P <0.0001) and TT4 ( standardized beta: 0.679, - 0.589, and 0.659, respectively; all P <0.0001). Conclusion: Poor maternal iron status predicts both higher TSH and lower TT4 concentrations during pregnancy in an area of borderline iodine deficiency.

KW - iodine supplementation

KW - subclinical hypothyroidism

KW - goitrous children

KW - cote-divoire

KW - body iron

KW - anemia

KW - women

KW - recommendations

KW - salt

KW - rats

U2 - 10.1210/jc.2007-1082

DO - 10.1210/jc.2007-1082

M3 - Article

VL - 92

SP - 3436

EP - 3440

JO - Journal of Clinical Endocrinology and Metabolism

JF - Journal of Clinical Endocrinology and Metabolism

SN - 0021-972X

IS - 9

ER -