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Cited by 74Thyroid Disorders and TreatmentsClinical Laboratory Practices and Quality ControlThyroid Cancer Diagnosis and Treatment

Narrow intra-individual variation of maternal thyroid function in pregnancy based on a longitudinal study on 132 women

Boas, Malene, Forman, Julie Lyng, Juul, Anders, Feldt-Rasmussen, Ulla, Skakkebæk, Niels Erik, Hilsted, Linda, Chellakooty, Marla, Larsen, Torben +3 more·2009·European Journal of Endocrinology
DOI 10.1530/eje-09-0579
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Abstract

Background: Adaptive alterations in maternal physiology cause changes in thyroid hormone levels throughout pregnancy, and precise biochemical evaluation is thus highly dependent on gestation-specific reference intervals and expected intra-individual variation. Objective: The aim of the study was the assessment of the intra-individual variation as well as the longitudinal course of thyroid hormones during normal pregnancy and factors that influence the normal reference range for thyroid function. For this purpose, a longitudinal statistical model was applied. Design: In a cohort of 132 pregnant women, serial blood samples were obtained and ultrasound scans were performed throughout pregnancy. Methods: Serum levels of TSH, free and total thyroxine (T 4), free and total triiodothyronine (T 3) as well as autoantibodies against thyroid peroxidase and thyroglobulin were measured in 979 serum samples. Results: Intra-individual variations of thyroid hormone concentrations were smaller than inter-individual variations (individuality index range: 0.38–0.71). Maternal height was positively associated with free T 4 (FT 4) (b=0.003; P=0.031) and pre-pregnancy body mass index with T 3 and free T 3 (b=0.017; <0.001 and b=0.007; P<0.001). Smoking was positively associated with T 4 and FT 4, but it was modulated by gestational age. Gestation-specific reference intervals for thyroid function variables from autoantibody-negative participants are presented. Conclusions: In accordance with the data from nonpregnant adults, intra-individual variations of thyroid hormones were smaller than inter-individual variations also during pregnancy. In the evaluation of thyroid function in pregnancy, the individual longitudinal course of thyroid hormones rather than absolute values should be considered. We present a longitudinal model for the prediction of maternal thyroid function tests in pregnant women.

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Crossref · 10.1530/eje-09-0579

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  • Serum TSH is variable during pregnancy according to gestation.

    “Serum TSH is, thus, higher in areas of both overt and partial iodine deficiency [8], very high in neonates [9], variable during pregnancy according to gestation [10], increasing at high age [11] and higher in some genetic population groups such as Ashkenazy Jews [12].”

    From Risks of suboptimal and excessive thyroid hormone replacement across ages (2023) · cites this paper as [10]

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Authors
Boas, M., Forman, J. L., Juul, A., Feldt-Rasmussen, U., Skakkebæk, N. E., Hilsted, L., Chellakooty, M., Larsen, T., Larsen, J. F., Petersen, J. H., & Main, K. M.
Affiliations
  • Rigshospitalet (DK)
  • University of Copenhagen (DK)
  • Herlev Hospital (DK)
Corresponding author
Boas, Malene
ORCID
Venue
European Journal of Endocrinology
Publisher
Oxford University Press (OUP)
Published
2009-12
Volume
161
Issue
6
Pages
903-910
ISSN
  • 0804-4643 (ISSN-L)
  • 1479-683X
DOI
10.1530/eje-09-0579
OpenAlex
W2095599824
Cited by
74
References
42
Citations by year
2026: 2 · 2025: 5 · 2024: 2 · 2023: 3 · 2022: 6 · 2021: 2 · 2020: 4 · 2019: 2 · 2018: 2 · 2017: 10 · 2016: 6 · 2015: 6 · 2014: 2 · 2013: 13 · 2012: 1
FWCI
2.18
Type
journal article
Language
en
Open access
closed
Locations
  • European Journal of Endocrinology (publishedVersion)
  • PubMed (publishedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (submittedVersion)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Physiology › Clinical Laboratory Practices and Quality Control
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
Keywords
maternal thyroid function, pregnancy, within-person variability, interindividual variability, thyroid hormones, thyroid-stimulating hormone, free thyroxine, free triiodothyronine, thyroid peroxidase antibodies, thyroglobulin antibodies, maternal height, body mass index, smoking, longitudinal modeling
MeSH terms
Adult, Body Height, Female, Humans, Longitudinal Studies, Middle Aged, Pregnancy, Reference Values, Thyroid Gland, Thyroxine, Triiodothyronine

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