Parity and 11-Year Serum Thyrotropin and Thyroid Autoantibody Change: A Longitudinal Population-Based Study

EMAS position statement: Thyroid disease and menopause

INTRODUCTION

Thyroid diseases are common in women in their late reproductive years; therefore, thyroid disease and menopause may co-exist. Both conditions may present with a wide range of symptoms, leading to diagnostic challenges and delayed diagnosis. Aim To construct the first European Menopause and Andropause Society (EMAS) statement on thyroid diseases and menopause.

MATERIALS AND METHODS

Literature review and consensus of expert opinion (EMAS executive board members/experts on menopause and thyroid disease).

SUMMARY RECOMMENDATIONS

This position paper highlights the diagnostic and therapeutic dilemmas in managing women with thyroid disease during the menopausal transition, aiming to increase healthcare professionals' awareness of thyroid disorders and menopause-related symptoms. Clinical decisions regarding the treatment of both conditions should be made with caution and attention to the specific characteristics of this age group while adopting a personalized patient approach. The latter must include the family history, involvement of the woman in the decision-making, and respect for her preferences, to achieve overall well-being.

Parity and Incidence of Thyroid Autoimmunity: A Population-Based Tehran Thyroid Study

Introduction: Autoimmune thyroid disease is the most common autoimmune disorder. Evidence regarding causes of the high prevalence and incidence of thyroid autoimmunity in women, and especially women of reproductive age, is still inconclusive and previous studies have suggested genetic, environmental, and existential factors to play a role in its pathogenesis. In this study, we aimed to investigate the effect of parity and other reproductive factors on the incidence of thyroid autoimmunity within the framework of the Tehran Thyroid Study (TTS). Materials and Methods: This study was conducted within the framework of the TTS and 1999 nonpregnant euthyroid thyroid peroxidase antibody (TPOAb) negative women were followed up for an average of 8.3 years. A pooled logistic regression model was used to assess the association (odds ratio) between time-dependent covariates parity, menopause, and abortion, and incidence of TPOAb positivity. Results: The total incidence rate of TPOAb positivity was 8.65 [7.35-10.18] per 1000 person-years. We found no significant association between changes in the number of parity and risk of developing TPOAb using multiple pooled logistic models both as crude effect and after adjustment for age, body mass index, and smoking. Similarly, there was no association between changes of parity, menopause, and abortion status, and incidence of TPOAb positivity. Conclusions: Parity does not seem to have an independent role in triggering thyroid autoimmunity, but vast immunological and physiological changes during pregnancy may act as a precipitating factor in the context of other genetic and environmental modifiers.

Increased risk of thyroid disease in Danish women with polycystic ovary syndrome: a cohort study

AIM

To investigate risk of thyroid disease in Danish women with PCOS.

DESIGN

National register-based study on women with PCOS in Denmark. 18,476 women had a diagnosis of PCOS in the Danish National Patient Register. PCOS Odense University Hospital (PCOS OUH, n = 1146) was an embedded cohort of women with PCOS and clinical and biochemical examination. Three age-matched controls were included for each woman with PCOS (n = 54,757). The main outcome measures were thyroid disease (hypothyroidism, Graves' disease, goiter, thyroiditis) according to hospital diagnosis codes and/or inferred from filled medicine prescriptions. Associations between baseline TSH and development of cardio-metabolic disease was examined in PCOS OUH.

RESULTS

The median (quartiles) age at inclusion was 29 (23-35) years and follow-up duration was 11.1 (6.9-16.0) years. The hazard ratio (95% CI) for thyroid disease development was 2.5 (2.3-2.7) (P < 0.001). The event rate of thyroid disease was 6.0 per 1000 patient-years in PCOS Denmark versus 2.4 per 1000 patient-years in controls (P < 0.001). Women in PCOS OUH with TSH ≥2.5 mIU/L (n = 133) had higher BMI (median 29 vs 27 kg/m2), wider waist, higher triglycerides and free testosterone by the time of PCOS diagnosis compared to women in PCOS OUH with TSH <2.5 mIU/L (n = 588). Baseline TSH did not predict later development of cardio-metabolic diseases in PCOS OUH.

CONCLUSIONS

The event rate of thyroid disease was significantly and substantially higher in women with PCOS compared to controls.

Temporal trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing across two phases of iodine fortification in Tasmania (1995-2013)

CONTEXT

Tasmania is an island state of the Australian Commonwealth with a well-documented history of mild iodine deficiency. Between 2001 and 2009, Tasmania experienced two incremental phases of iodine fortification.

OBJECTIVE

To examine trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing and their relationship to different phases of iodine nutrition in the Tasmanian population between 1995 and 2013.

DESIGN

Retrospective longitudinal study.

SETTING AND PARTICIPANTS

The major primary care and largest public hospital pathology providers in Tasmania submitted data for all TSH and ATPO tests performed between 1995 and 2013. Data linkage methodology was used to determine trends in TSH and ATPO testing.

RESULTS

A total of 1.66 million TSH assessments, involving 389,910 individual patients, were performed in Tasmania between 1995 and 2013. There was approximately a fourfold increase in the overall rate of TSH testing during this period with the rate of incident TSH assessment remaining relatively stable over the study period. The incidence of overt suppression and elevation of TSH (TSH≤0.1 mIU/L and ≥10 mIU/L) declined 62.3% and 59.7%, respectively, with a trend for increased incidence of borderline TSH elevation ≥4.0 mIU/L. The incidence of thyroid autoimmunity as determined by the proportion of abnormal ATPO results remained stable, with the absolute number of positive test results increasing during the study period.

CONCLUSION

Iodine supplementation of this mildly iodine-deficient population was not associated with an obvious increase in incidence of overt thyroid dysfunction or autoimmunity. Whilst the volume of TSH testing increased over the study period, the increase was driven by patients undergoing follow-up TSH assessments.

Parity and Risk of Thyroid Autoimmunity Based on the NHANES (2001-2002, 2007-2008, 2009-2010, and 2011-2012)

CONTEXT

Autoimmune thyroid disease is more common in women than in men. Fetal microchimerism has been implicated as a potential explanation for this disparity.

OBJECTIVE

The objective of this study was to evaluate the relationship between parity and thyroid autoimmunity in the US population.

DESIGN, SETTING, PATIENTS

The National Health and Nutrition Examination Survey was used to identify females with antithyroperoxidase (TPOAb) and antithyroglobulin antibody (TgAb) measurements and parity data. Subjects (n = 4864) were categorized as never pregnant (n = 909) or previously pregnant (n = 3955). The association of parity with thyroid autoantibodies was examined both qualitatively and quantitatively. Thyroid autoimmunity was defined as TPOAb and/or TgAb titers above the reference limits.

RESULTS

Previous pregnancy carried an odds ratio (OR) of 1.55 [95% confidence interval (CI): 1.26 to 1.91] for thyroid autoimmunity compared with never pregnant. Number of pregnancies was associated with thyroid autoimmunity: OR = 1.37 (95% CI: 1.02 to 1.84); 1.4 (95% CI: 1.08 to 1.81); 1.52 (95% CI: 1.18 to 1.96); and 1.73 (95% CI: 1.38 to 2.18) for 1, 2, 3, and ≥4 pregnancies, respectively. Because ever-pregnant women differed in several variables-age, race, smoking status, history of thyroid disease, and urinary iodine level-from never-pregnant women (P < 0.001), a multivariate regression analysis was performed, which showed no association of pregnancy with thyroid autoimmunity. The association was further examined utilizing an age-matched analysis, which confirmed the absence of an association between thyroid autoimmunity and parity.

CONCLUSION

Although we initially observed a strong association between parity and thyroid autoimmunity, after controlling for age and other variables, we were unable to identify an association.

Incidence of thyroid dysfunction in an Iranian adult population: the predictor role of thyroid autoantibodies: results from a prospective population-based cohort study

Background

The prevalence of thyroid dysfunction is high in Isfahan, an area of iodine sufficient in Iran. The aim of this study is to investigate the incidence of thyroid dysfunctions in adults of metropolitan Isfahan and to determine the role of thyroid autoantibodies.

Methods

In a population-based cohort study in 2006–2011, we measured TSH, T4, T3, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) in 618 out of 2254 people who were euthyroid in 2006. The incidence rates per 1000 person-year (pr) were calculated. The odds ratio (OR), relative risk (RR), and 95% confidence interval (95% CI) were calculated based on logistic regression to quantify the potential predictors of thyroid dysfunction. The receiver-operator characteristic (ROC) analysis along with area under the curve (AUC) was used to determine the optimal cutoff values for baseline TPOAb and TgAb as predictors of thyroid dysfunction.

Results

Within a 6-year follow-up, the incidence rate of hypothyroidism was 3.3 in women and 2.1 in men while the incidence rate of hyperthyroidism was 3.8 in women and none in men per 1000 (person-year). A cutoff value of TPOAb at 38 IU/mL was obtained to differentiate the patients with hypothyroidism and hyperthyroidism, with specificity of 0.75 and sensitivity of 0.76, and AUC (CI 95%) of 0.882 (0.743–1.02), P = 0.01 and 0.817 (0.600–1.035) P = 0.033, respectively. There is a statistically significant association of hypothyroidism and hyperthyroidism with positive TPOAb [RR (CI 95%): 1.99 (1.27–3.13) and 2.20 (1.23–3.95), respectively].

Conclusions

The incidence rate of thyroid dysfunction is high in Isfahan, and higher TPOAb concentration is its strong predictor.

Hypothyroidism incidence in and around pregnancy: a Danish nationwide study

OBJECTIVE

Immunological changes in and after a pregnancy may influence the onset of autoimmune diseases. An increased incidence of hyperthyroidism has been observed both in early pregnancy and postpartum, but it remains to be studied if the incidence of hypothyroidism varies in a similar way.

DESIGN

Population-based cohort study using Danish nationwide registers.

METHOD

All women who gave birth to a singleton live-born child in Denmark from 1999 to 2008 (n = 403 958) were identified, and data on hospital diagnosis of hypothyroidism and redeemed prescriptions of thyroid hormone were extracted. The overall incidence rate (IR) of hypothyroidism during 1997-2010 and the IR in three-month intervals before, during and after the woman's first pregnancy in the study period were calculated and compared with the IR of hyperthyroidism.

RESULTS

Altogether 5220 women were identified with onset of hypothyroidism from 1997 to 2010 (overall IR 92.3/100 000/year) and 1572 women developed hypothyroidism in the period from 2 years before to 2 years after birth of the first child in the study period. The incidence of hypothyroidism decreased during the pregnancy (incidence rate ratio (IRR) vs overall IR in the rest of the study period: first trimester: 0.89 (95% CI: 0.66-1.19), second trimester: 0.71 (0.52-0.97), third trimester: 0.29 (0.19-0.45)) and increased after birth with the highest level at 4-6 months postpartum (IRR 3.62 (2.85-4.60)).

CONCLUSION

These are the first population-based data on the incidence of hypothyroidism in and around pregnancy. The incidence declined during pregnancy followed by a sharp increase postpartum. Notably, hypothyroidism as opposed to hyperthyroidism showed no early pregnancy increase.