The prevalence of thyroid dysfunction and autoimmunity in women with history of miscarriage or subfertility
Research output: Contribution to journal › Article › peer-review
Authors
Colleges, School and Institutes
External organisations
- UCL
- Assisted Conception Unit, Guy’s and St. Thomas’ Foundation Trust
- THE UNIVERSITY OF WARWICK
- Warwick Medical School
Abstract
Objective
To describe the prevalence of and factors associated with different thyroid dysfunction phenotypes in women who are asymptomatic preconception.
Design
Observational cohort study.
Setting
A total of 49 hospitals across the United Kingdom between 2011 and 2016.
Participants
Women aged 16 to 41years with history of miscarriage or subfertility trying for a pregnancy.
Methods
Prevalences and 95% confidence intervals (CIs) were estimated using the binomial exact method. Multivariate logistic regression analyses were conducted to identify risk factors for thyroid disease.
Intervention
None.
Main Outcome Measure
Rates of thyroid dysfunction.
Results
Thyroid function and thyroid peroxidase antibody (TPOAb) data were available for 19213 and 19237 women, respectively. The prevalence of abnormal thyroid function was 4.8% (95% CI, 4.5-5.1); euthyroidism was defined as levels of thyroid-stimulating hormone (TSH) of 0.44 to 4.50 mIU/L and free thyroxine (fT4) of 10 to 21 pmol/L. Overt hypothyroidism (TSH > 4.50 mIU/L, fT4 < 10 pmol/L) was present in 0.2% of women (95% CI, 0.1-0.3) and overt hyperthyroidism (TSH < 0.44 mIU/L, fT4 > 21 pmol/L) was present in 0.3% (95% CI, 0.2-0.3). The prevalence of subclinical hypothyroidism (SCH) using an upper TSH concentration of 4.50 mIU/L was 2.4% (95% CI, 2.1-2.6). Lowering the upper TSH to 2.50 mIU/L resulted in higher rates of SCH, 19.9% (95% CI, 19.3-20.5). Multiple regression analyses showed increased odds of SCH (TSH > 4.50 mIU/L) with body mass index (BMI) ≥ 35.0 kg/m2 (adjusted odds ratio [aOR] 1.71; 95% CI, 1.13-2.57; P = 0.01) and Asian ethnicity (aOR 1.76; 95% CI, 1.31-2.37; P < 0.001), and increased odds of SCH (TSH ≥ 2.50 mIU/L) with subfertility (aOR 1.16; 95% CI, 1.04-1.29; P = 0.008). TPOAb positivity was prevalent in 9.5% of women (95% CI, 9.1-9.9).
Conclusions
The prevalence of undiagnosed overt thyroid disease is low. SCH and TPOAb are common, particularly in women with higher BMI or of Asian ethnicity. A TSH cutoff of 2.50 mIU/L to define SCH results in a significant proportion of women potentially requiring levothyroxine treatment.
Details
Original language | English |
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Pages (from-to) | 2667–2677 |
Journal | Journal of Clinical Endocrinology and Metabolism |
Volume | 105 |
Issue number | 8 |
Early online date | 17 Jun 2020 |
Publication status | Published - 1 Aug 2020 |