The Association Between Blood Pressure and Normal Range Thyroid Function Tests in a Population Based Tehran Thyroid Study

Amouzegar, Atieh; Heidari, Mansour; Gharibzadeh, Safoora; Mehran, Ladan; Tohidi, Maryam; Azizi, Fereidoun

doi:10.1055/s-0035-1564131

Cited by 14 publications

(12 citation statements)

References 25 publications

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“…On the other hand, results of the present study showed that in the RR, serum FT4 exerts more notable effects on BP, especially SBP, compared to serum TSH. This reciprocal finding regarding the effect of serum TSH and FT4 has been observed in several cross-sectional [23,27] and cohort studies extracted from TTS data [28] also other surveys [29]. It is suggested that FT4 is a more reliable index for evaluation of thyroid function at the cellular levels; moreover, TSH changes following deviations in serum levels of FT4 is less vigorous whenever deviations are minimal [30].…”

Section: Total Populationsupporting

confidence: 53%

“…Thyroid function has complex direct and indirect effects on BP and several mechanisms have been speculated for explaining the role of thyroid hormones in BP regulation [19]. Data about changes in BP across the spectrum of thyroid dysfunction is well documented; but evidence regarding these changes across the range of euthyroidism is conflicting in view of cross-sectional studies [20][21][22][23] and very scarce and inconsistent in longitudinal surveys. Moreover, none of them have considered serum thyroid hormones; herein, we present an overview on the main results of the longitudinal studies.…”

Section: Discussionmentioning

confidence: 99%

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Associations Between Thyroid and Blood Pressure in Euthyroid Adults: A 9-Year Longitudinal Study

et al. 2018

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Longitudinal studies considering associations between thyroid function in the reference range (RR) with blood pressure (BP) are scarce and contradictory. We aimed to investigate the associations of serum thyrotropin (TSH) and free T4 (FT4) with different components of BP also incident prehyperetension (preHTN) and HTN during a 9-year follow-up. A sum of 2282 euthyroid individuals from an ongoing population-based cohort study were selected. A sex-stratified multivariate generalized estimating equation (GEE) method was employed. Moreover, a multivariate transitional model was used considering preceding BP status as a predictor of dichotomous outcomes of preHTN and HTN. Multivariate-adjusted GEE analysis revealed a decreasing trend for systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP) and pulse pressure (PP) throughout the study period in both men and women, either adjusted for serum TSH or FT4 levels. Serum FT4 within the RR was positively associated with all BP parameters in total population and in men, but serum TSH had a statistically significant mild increasing effect only on SBP, DBP and MAP of men. Multivariate transitional model found no association between serum TSH levels within the reference range (RR) and BP status; regarding serum FT4, a 1 ng/dl higher FT4 was associated with 40% increased risk of preHTN [OR (95% CI), 1.40 (1.02-1.90)], but not with HTN [OR (95% CI), 0.93 (0.80-1.09)]. It is concluded that serum FT4 within the RR is more strongly associated with BP parameters compared to TSH. This association is not consistent between men and women. Moreover, higher FT4 is associated with increased risk of preHTN.

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Section: Total Populationsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Associations Between Thyroid and Blood Pressure in Euthyroid Adults: A 9-Year Longitudinal Study

et al. 2018

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“…One study indicates that people with higher serum TSH level within normal range had elevated BP than those with lower serum TSH level in normal range [32]. However, another study from 4,985 euthyroid individuals reveals that there is no association in between serum TSH and BP [34]. In our study, results showed serum TSH had positive relationship with SBP and DBP.…”

Section: Discussioncontrasting

confidence: 46%

Age-related change in thyroid-stimulating hormone: a cross-sectional study in healthy euthyroid population

et al. 2018

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This cross-sectional study aimed to examine changes in thyroid-stimulating hormone (TSH) concentration over age in China and investigate relationship between TSH and risk factors for cardiovascular disease (CVD) among euthyroid subjects. TSH, free triiodothyronine (FT3), free thyroxine (FT4), blood lipid, and glucose were measured. 7,693 individuals were subdivided into different age groups. Associations between TSH and CVD risk factors [age, body mass index (BMI), systolic and diastolic blood pressure, total cholesterol (TC), triglycerides, low density lipoprotein-cholesterol (LDL-C) and high density lipoprotein-cholesterol (HDL-C) and fasting plasma glucose (FPG)] were evaluated with Pearson correlation analysis. Results showed that 2.5th percentile for TSH was consistent across age groups, whereas 97.5th percentile increased in subjects older than 40 years with upper limit being 6.83 mIU/L in subjects aged 60-69 years and 8.07 mIU/L in those older than 70 years. The age-speciﬁc upper limits reclassiﬁcation rate was higher in all age bands as compared to the common cut-off value. TSH was positively associated with age, SBP, DBP, TC and LDL-C and negatively with FT3 and FT4. Serum TSH within new reference range had a linear correlation with SBP, TC and LDL-C in subjects aged <60 years. There were no significant differences in BMI, blood pressure, lipid profile or FPG among subjects 60-69 and older than or equal to 70 years. Elevated TSH within new reference range is associated with risk factors for CVD in subjects aged <60 years. Thus, there might be age-related difference in the relationship between CVD risk factors and elevated serum TSH.

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“…47 In contrast to the positive association between fT4 and AF, we did not find an association between TSH levels in the reference range and AF, and this pattern of a positive association between fT4 but not TSH values in the reference range has also been shown for other adverse cardiac outcomes including congestive heart failure 14 and sudden cardiac death, 15 as well as for blood pressure. 48 These results of the effect of normal thyroid function on the heart are in contrast to the findings of a statistically significant inverse association between TSH levels within the reference range and dementia, whereas no significant association between fT4 levels in the normal range and rates of dementia was found in this study, 14 suggesting that thyroid hormone metabolism and action differs between target organs such as the heart and brain because of differences in deiodinase activity and thyroid hormone receptor expression; 47 these differences may explain why some clinical phenotypes are associated with fT4 only, some with TSH only, and others with both. These findings are also consistent with the observation that fT4 concentrations may differ even among euthyroid persons with the same TSH values: 49 individuals with higher fT4 values have higher cardiac exposure to thyroid hormones and are consecutively at a higher risk of AF, which is reflected by the findings of our study.…”

Section: Discussionmentioning

confidence: 99%

Thyroid Function Within the Normal Range, Subclinical Hypothyroidism, and the Risk of Atrial Fibrillation

et al. 2017

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Background Atrial fibrillation (AF) is a highly prevalent disorder leading to heart failure, stroke, and death. Enhanced understanding of modifiable risk factors may yield opportunities for prevention. The risk of AF is increased in subclinical hyperthyroidism, but it is uncertain whether variations in thyroid function within the normal range or subclinical hypothyroidism are also associated with AF. Methods We conducted a systematic review and obtained individual participant data from prospective cohort studies that measured thyroid function at baseline and assessed incident AF. Studies were identified from MEDLINE and EMBASE databases from inception to July 27, 2016. The euthyroid state was defined as thyroid stimulating hormone (TSH) 0.45–4.49mIU/l, and subclinical hypothyroidism as TSH 4.5–19.9mIU/l with free thyroxine (fT4) levels within reference range. The association of TSH levels in the euthyroid and subclinical hypothyroid range with incident AF was examined using Cox proportional hazards models. In euthyroid participants, we additionally examined the association between fT4 levels and incident AF. Results Of 30,085 participants from 11 cohorts (278,955 person-years of follow-up), 1,958 (6.5%) had subclinical hypothyroidism, and 2,574 individuals (8.6%) developed AF during follow-up. TSH at baseline was not significantly associated with incident AF in euthyroid participants or those with subclinical hypothyroidism. Higher fT4 levels at baseline in euthyroid individuals were associated with increased AF risk in age- and sex-adjusted analyses (hazard ratio=1.45; 95% confidence interval, 1.26–1.66, for the highest quartile vs the lowest quartile of fT4, p for trend ≤0.001 across quartiles). Estimates did not substantially differ after further adjustment for preexisting cardiovascular disease. Conclusion In euthyroid individuals, higher circulating fT4 levels, but not TSH levels, are associated with increased risk of incident AF.

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The Association Between Blood Pressure and Normal Range Thyroid Function Tests in a Population Based Tehran Thyroid Study

Cited by 14 publications

References 25 publications

Associations Between Thyroid and Blood Pressure in Euthyroid Adults: A 9-Year Longitudinal Study

Associations Between Thyroid and Blood Pressure in Euthyroid Adults: A 9-Year Longitudinal Study

Age-related change in thyroid-stimulating hormone: a cross-sectional study in healthy euthyroid population

Thyroid Function Within the Normal Range, Subclinical Hypothyroidism, and the Risk of Atrial Fibrillation

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