Evaluating the Progression to Hypothyroidism in Preconception Euthyroid Thyroid Peroxidase Antibody-Positive Women

Sofia Gill, Versha Cheed, Victoria A H Morton, Dayna Gill, Kristien Boelaert, Shiao Chan, Arri Coomarasamy, Rima K Dhillon-Smith*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

CONTEXT: Thyroid peroxidase antibody (TPOAb) positivity is prevalent in women of reproductive age and predisposes to thyroid dysfunction, particularly hypothyroidism, which has adverse effects on pregnancy.

OBJECTIVE: This study aimed to report the rate of development of abnormal thyroid function among initially euthyroid TPOAb-positive women recruited into the TABLET trial, to identify factors associated with the development of hypothyroidism, and to compare outcomes between euthyroid and treated hypothyroid individuals.

METHODS: This observational cohort study, conducted at 49 UK hospitals between 2011 and 2016, included euthyroid TPOAb-positive women 16 to 40 years of age with a history of miscarriage or subfertility, planning pregnancy, randomized to levothyroxine 50 mcg daily or placebo. Abnormal thyroid function, conception rate, and live birth rate (LBR) ≥34 weeks were analyzed.

RESULTS: Among the women, 70/940 (7.4%) developed subclinical (SCH) or overt (OH) hypothyroidism: 27/470 taking levothyroxine and 43/470 placebo (relative risk [RR] 0.63; 95% CI, 0.39-1.00; P = 0.05); 83% of cases emerged prepregnancy. Baseline median serum TSH concentrations and TPOAb titers were significantly higher in those who developed hypothyroidism vs those who did not (P < 0.001). Treated SCH/OH demonstrated a higher failure-to-conceive rate compared with euthyroid women (adjusted RR 2.02 [1.56-2.62]; P < 0.001). The LBR ≥ 34 weeks was similar in the treated SCH/OH and euthyroid groups (adjusted RR 1.09 [0.77-1.55]; P = 0.6).

CONCLUSION: Approximately 7% of euthyroid TPOAb-positive women will develop hypothyroidism within 1 year preconception or in pregnancy. Conception rates are lower in women with treated SCH/OH compared with euthyroid women, but LBR are comparable. Thyroid function in TPOAb-positive women should be monitored regularly, when trying to conceive, to ensure prompt diagnosis and appropriate treatment initiation.

Original languageEnglish
Pages (from-to)124-134
Number of pages11
JournalThe Journal of clinical endocrinology and metabolism
Volume108
Issue number1
Early online date14 Sept 2022
DOIs
Publication statusPublished - Jan 2023

Bibliographical note

Funding:
This study was directly linked to the TABLET Trial, funded by the NIHR Efficacy and Mechanism Evaluation (EME) programme (grant number 09/100/10).

© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Keywords

  • Female
  • Humans
  • Pregnancy
  • Abortion, Spontaneous
  • Autoantibodies
  • Hypothyroidism/drug therapy
  • Iodide Peroxidase
  • Thyroid Diseases/complications
  • Thyrotropin
  • Thyroxine/therapeutic use
  • Adolescent
  • Young Adult
  • Adult

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