Elsevier

Maturitas

Volume 62, Issue 3, 20 March 2009, Pages 301-305
Maturitas

Thyroid stimulating hormone is associated with metabolic syndrome in euthyroid postmenopausal women

https://doi.org/10.1016/j.maturitas.2009.01.007Get rights and content

Abstract

Objectives

The aim of this study was to investigate the relationship between thyroid stimulating hormone (TSH) and metabolic syndrome (MetS) in euthyroid postmenopausal women.

Methods

We conducted a cross-sectional study of 2205 Korean postmenopausal women. Subjects who were not euthyroid were excluded. Fasting TSH, free thyroxine (FT4), insulin, glucose, and the level of insulin resistance, estimated by the homeostasis model assessment for insulin resistance (HOMA-IR) were measured. MetS was defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria.

Results

TSH levels were associated with total cholesterol, LDL-cholesterol, triglycerides and diastolic blood pressure. Using a multiple linear regression analysis, LDL-cholesterol, and triglycerides levels were identified as independently associated with TSH. Multivariate logistic regression analysis determined that TSH levels strongly contributed to MetS. Compared with the lower most quartile (TSH, 0.3–1.44 mIU/L), the adjusted odds ratio for MetS was 1.95 in the upper most quartile (TSH, 2.48–4.00 mIU/L). The prevalence of MetS increased as the TSH quartile showed a gradual increase.

Conclusion

We found a close relationship between TSH and MetS in euthyroid postmenopausal women. Therefore, more attention should be focused on postmenopausal women with high normal TSH levels for the management of cardiovascular disease.

Introduction

Cardiovascular disease (CVD) is the leading cause of death in women, especially postmenopausal women [1]. It is generally well accepted that hypothyroidism and metabolic syndrome (MetS) are both associated with increased risk for CVD. MetS, which describes a cluster of cardiovascular risk factors including obesity, atherogenic dyslipidemia, hypertension, and insulin resistance, increases the risk of developing CVD [2]. Overt hypothyroidism, with its accompanying hypercholesterolemia and hypertension, is associated with CVD [3], [4].

It has long been observed that thyroid dysfunction is associated with various cardiovascular risk factors and that these risk factors are similar to the components of MetS. Therefore, thyroid dysfunction may have an impact on the prevalence of MetS. However, most cardiovascular events occur in subjects with normal thyroid function, and conflicting results have been reported about the association between thyroid stimulating hormone (TSH) at the upper limit of the normal range and cardiovascular risk factors [5], [6], [7]. In many women, features of MetS such as abdominal adiposity, insulin resistance, and dyslipidemia develop with the transition from pre- to postmenopause [8], [9], [10], [11], [12], [13]. Thus, the question of whether there is an association between thyroid function and MetS in euthyroid postmenopausal women is important. There have been only a few studies on the effects of TSH on the prevalence of MetS. We investigated the association between serum TSH level and the prevalence of MetS and its components and serum lipids in euthyroid Korean postmenopausal women.

Section snippets

Subjects and measurement

The study population consisted of 2205 Korean postmenopausal women who were self-referred for a routine health check-up at Korea University Anam Hospital (Seoul, Korea) from November 2006 to November 2007. All participants were interviewed and examined by the attending gynecologist. Menopause was defined as cessation of menstruation for more than 1 year. The Ethics Committee of our institution approved this study and all subjects provided written consent.

To avoid the influence of confounding

Results

Table 1 displays the baseline characteristics of the study subjects. The mean age was 58.76 ± 5.97 years and the mean TSH level was 1.79 ± 1.59 mIU/L. We evaluated the association between TSH and cardiovascular risk factors, including the components of MetS. In simple correlation analysis, TSH was positively correlated with diastolic blood pressure, total cholesterol, LDL-C and triglycerides (Table 2). Using a multiple linear regression model, LDL-C (β = 0.105; P = 0.004) and triglycerides (β = 0.089; P = 

Discussion

We found that TSH levels were associated with MetS in euthyroid postmenopausal women independently of well-known MetS risk factors (age, YSM, BMI, HOMA-IR, life style factors). TSH levels were positively correlated with diastolic blood pressure, total cholesterol, LDL-C and triglycerides. Moreover, LDL-C and triglycerides were independently associated with TSH. Finally, subjects with high normal TSH levels had a 1.95-fold increased risk of MetS, as compared to those with low normal TSH levels.

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