The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Mikael Lantz

Mikael Lantz

Consultant

Mikael Lantz

Pregnant Women on Thyroxine Substitution Are Often Dysregulated in Early Pregnancy.

Author

  • Bengt Hallengren
  • Mikael Lantz
  • Bengt Andréasson
  • Lars Grennert

Summary, in English

Background: Thyroid hormones are important for normal fetal development. Maternal hypothyroidism during early pregnancy is associated with impaired neuropsychological development of children and other adverse outcomes. The primary aim of this prospective study was to determine whether thyroxine-treated pregnant women with hypothyroidism are adequately thyroxine substituted in early pregnancy. A secondary aim was to determine if fetal loss differed between females with thyrotropin (TSH) values within and outside the reference range at their first TSH test, scheduled for 1-2 weeks after verification of pregnancy. Methods: This was a prospective open-labeled study. During the years 1997-2002, 119 consecutive pregnancies in 101 females with thyroid diseases were followed at the Department of Endocrinology, Malmö University Hospital. At the first visit, 63 patients, median age 30 years (range 17-45 years), were on thyroxine substitution therapy for hypothyroidism. In these patients 83% were in their first trimester at the time of the initial test. Results: Of the 63 patients on thyroxine substitution for hypothyroidism 32 (51%; Group A) patients had serum TSH values within the reference range at their initial test and 31 (49%; Group B) had serum TSH values outside the reference range. Twelve (19%) had TSH values of <0.40 mIU/L and 19 (30%) had TSH values of >4.0 mIU/l. The fetal loss was 2 of 32 (6%) in Group A compared to 9 of 31 (29%) in Group B (p < 0.05). Conclusions: In 49% of pregnant women on thyroxine substitution, serum TSH values were outside the reference range when first tested, generally in the first trimester. Fetal loss was significantly greater in pregnant women with abnormal TSH values compared to those with normal TSH values. Thyroid function in pregnant women on thyroxine substitution should be monitored early in pregnancy and carefully followed during pregnancy. The thyroxine dose should be increased as needed early in pregnancy to avoid hypothyroidism.

Department/s

  • Genomics, Diabetes and Endocrinology
  • Preventive Paediatrics
  • Department of Clinical Sciences, Malmö

Publishing year

2009

Language

English

Pages

391-394

Publication/Series

Thyroid

Volume

19

Document type

Journal article

Publisher

Mary Ann Liebert, Inc.

Topic

  • Endocrinology and Diabetes

Status

Published

Research group

  • Genomics, Diabetes and Endocrinology
  • Preventive Paediatrics

ISBN/ISSN/Other

  • ISSN: 1557-9077