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SYSTEMATIC REVIEW article

Front. Endocrinol.
Sec. Thyroid Endocrinology
Volume 16 - 2025 | doi: 10.3389/fendo.2025.1533169

Association of Iron Status Indicators with Thyroid Hormone Concentrations During Pregnancy: A Systematic Review and

Provisionally accepted
Mohammadamin Parsaei Mohammadamin Parsaei 1Mohadese Dashtkoohi Mohadese Dashtkoohi 2Elahe Amirkhalili Elahe Amirkhalili 3Mohammadreza Chashmyazdan Mohammadreza Chashmyazdan 4Tim IM Korevaar Tim IM Korevaar 5*Pantea Nazeri Pantea Nazeri 1*
  • 1 Breastfeeding Research Center, Family Health Research Institute, Tehran University of Medical Sciences, Tehran, Alborz, Iran
  • 2 Vali-E-Asr Reproductive Health Research Center, Tehran, Alborz, Iran
  • 3 Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Alborz, Iran
  • 4 Khoy University of Medical Sciences, Khoy, West Azerbaijan, Iran
  • 5 Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, Netherlands

The final, formatted version of the article will be published soon.

    Background: Maternal thyroid hormones play a vital role in fetal development, and imbalances can lead to adverse outcomes. Iron deficiency may impair thyroid function due to iron's essential role in iodine oxidation during thyroid hormone synthesis. This review examines the relationship between various indicators of maternal iron status and thyroid function during pregnancy. Methods: We conducted a systematic search in MEDLINE/PubMed, Web of Science, Embase, Scopus, and the Cochrane Library for studies published up to 2023. Meta-analyses determined pooled thyroid hormone levels in patientswith and without iron deficiency, using serum ferritin (cut-off = 30 µg/L) and hemoglobin (cutoff = 11 g/dL). Meta-regression analyses examined linear relationships between iron status indicators and thyroid hormones. Results: Forty-seven studies involving 53,152 pregnant women were included. Meta-analysis showed no significant difference in thyroid-stimulating hormone, free T4, or total T4 when considering serum ferritin levels in iron-deficient versus iron-sufficient individuals. However, regarding hemoglobin levels, iron deficiency was associated with higher thyroid-stimulating hormone (2.31 mIU/L vs. 1.75 mIU/L) and lower free T4 (10.7 pmol/L vs. 13.3 pmol/L), but not total T4. Meta-regression revealed no significant associations between serum ferritin and thyroid hormones. Conversely, maternal hemoglobin levels were inversely associated with thyroid-stimulating hormone (P-value = 0.009) and directly associated with free T4 (P-value < 0.001), with no significant link to total T4.Maternal hemoglobin levels are more strongly correlated with thyroid function than serum ferritin levels. This suggests that monitoring hemoglobin could enhance the early detection and management of thyroid dysfunction during pregnancy.* Studies with ≥7 points were considered high quality. The asterisks denote the score(s) for each criterion. One asterisk denotes a score of 1, and 2 asterisks denote a score of

    Keywords: Hemoglobin, Iron, Pregnancy, Serum ferritin, Thyroid Hormones

    Received: 23 Nov 2024; Accepted: 06 Jan 2025.

    Copyright: © 2025 Parsaei, Dashtkoohi, Amirkhalili, Chashmyazdan, Korevaar and Nazeri. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Tim IM Korevaar, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, Netherlands
    Pantea Nazeri, Breastfeeding Research Center, Family Health Research Institute, Tehran University of Medical Sciences, Tehran, Alborz, Iran

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