An Examination of the Relationship Between Normal Range Thyrotropin and Cardiovascular Risk Parameters: A Study in Healthy Women
ABSTRACT To investigate the relationship between thyrotropin concentrations within the accepted reference range and cardiovascular risk.
Initially, 728 women aged 45-60 years were enrolled over a 12-month period. All participants underwent full cardiovascular assessment, including detailed health questionnaire, sphygomanometry, body mass index (BMI) calculation, fasting glucose and lipid profiling, and measurement of serum thyrotropin concentrations. Patients whose thyrotropin concentrations were within the reference range (0.5-4.5 mU/L) were divided into quartiles (n = 629). The means of cardiovascular risk parameters between the first (n = 158) and fourth (n = 157) quartile were compared. Subsequently, the relationships between thyrotropin concentration and risk parameters for cardiovascular disease were examined.
This study demonstrates that, within the reference range, increasing thyrotropin concentrations are associated with increasing risk parameters for the development of cardiovascular disease. Subjects with thyrotropin concentrations within the uppermost quartile of the reference range had significantly increased waist circumference, BMI, glucose, triglyceride, and systolic blood pressure measurements when compared to those in the lowermost quartile. Furthermore, significant relationships between thyrotropin and waist circumference, BMI, and fasting glucose and triglycerides concentrations were demonstrated. Finally, independent relationships between thyrotropin and both fasting glucose and triglyceride concentrations were demonstrated.
Within the reference range, increasing thyrotropin concentrations are associated with increasing cardiovascular risk parameters. Fasting glucose and triglycerides have been shown to be independently associated with thyrotropin concentration.
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- "However, the practice of measuring TSH levels twice and applying more stringent exclusion criteria made the impact of an acute setting or heart disease minimized. In addition, most of studies on thyroid function that have been published have adopted measuring TSH levels at one time point [6,7,10]. Third, the power of the present study could have been stronger with a larger number of study subjects. "
ABSTRACT: The relationship between TSH and the lipid profile is contradictory because few studies have excluded the potential influence of the thyroid hormones (TH). The aim of the present study was to evaluate the relationship between serum TSH levels and the lipid profile independent of TH. 1302 CHD patients diagnosed by coronary angiography were retrospectively studied. The prevalence and distribution of thyroid dysfunction were analyzed first. To assess the impact of TSH on serum lipids, Pearson's correlation analysis was performed after adjustments for classic factors and TH. To calculate the extent of the effect of TSH on the serum cholesterol level, the partial least squares method and additional statistical methods were used. After the exclusions, a total of 568 patients (270 males and 298 females with a mean age of 63.56 ± 11.376 years) were selected. The prevalence of thyroid dysfunction among the patients was 18.66%, and the prevalence of hypothyroidism (15.32%) was higher than that of hyperthyroidism (3.34%). Even after adjusting for confounding factors, such as sex, age, smoking status, fasting plasma glucose levels and TH, a significant positive impact of TSH on the serum total cholesterol (TC) level was revealed (r = 0.095, p = 0.036). Each 1 mIU/L increase in the TSH level might be linked to a 0.015580712 mmol/L elevation of the serum TC value. TSH can increase the TC level in CHD patients independent of TH. The present study suggests a potential physiological role of TSH and the importance of maintaining an appropriate TSH level in CHD patients.Nutrition & Metabolism 05/2012; 9(1):44. DOI:10.1186/1743-7075-9-44 · 3.36 Impact Factor
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ABSTRACT: Data on the association between subclinical thyroid dysfunction and coronary heart disease (CHD) and mortality are conflicting. To summarize prospective evidence about the relationship between subclinical thyroid dysfunction and CHD and mortality. MEDLINE (1950 to January 2008) without language restrictions and reference lists of retrieved articles were searched. Two reviewers screened and selected cohort studies that measured thyroid function and then followed persons prospectively to assess CHD or mortality. By using a standardized protocol and forms, 2 reviewers independently abstracted and assessed studies. Ten of 12 identified studies involved population-based cohorts that included 14 449 participants. All 10 population-based cohort studies examined risks associated with subclinical hypothyroidism (2134 CHD events and 2822 deaths), whereas only 5 examined risks associated with subclinical hyperthyroidism (1392 CHD events and 1993 deaths). In a random-effects model, the relative risk (RR) for subclinical hypothyroidism for CHD was 1.20 (95% CI, 0.97 to 1.49; P for heterogeneity = 0.14; I(2 )= 33.4%). Risk estimates were lower when higher-quality studies were pooled (RR, 1.02 to 1.08) and were higher among participants younger than 65 years (RR, 1.51 [CI, 1.09 to 2.09] for studies with mean participant age <65 years and 1.05 [CI, 0.90 to 1.22] for studies with mean participant age > or =65 years). The RR was 1.18 (CI, 0.98 to 1.42) for cardiovascular mortality and 1.12 (CI, 0.99 to 1.26) for total mortality. For subclinical hyperthyroidism, the RR was 1.21 (CI, 0.88 to 1.68) for CHD, 1.19 (CI, 0.81 to 1.76) for cardiovascular mortality, and 1.12 (CI, 0.89 to 1.42) for total mortality (P for heterogeneity >0.50; I(2 )= 0% for all studies). Individual studies adjusted for different potential confounders, and 1 study provided only unadjusted data. Publication bias or selective reporting of outcomes could not be excluded. Subclinical hypothyroidism and hyperthyroidism may be associated with a modest increased risk for CHD and mortality, with lower risk estimates when pooling higher-quality studies and larger CIs for subclinical hyperthyroidism.Annals of internal medicine 06/2008; 148(11):832-45. DOI:10.7326/0003-4819-148-11-200806030-00225 · 16.10 Impact Factor
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ABSTRACT: The aim of this study was to investigate the relationship between thyroid stimulating hormone (TSH) and metabolic syndrome (MetS) in euthyroid postmenopausal women. 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. 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. 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.Maturitas 03/2009; 62(3):301-5. DOI:10.1016/j.maturitas.2009.01.007 · 2.86 Impact Factor