Thyroid Feedback Quantile-Based Index Is Associated With Blood Pressure and Other Hemodynamic Measures: A Cross-sectional Study.

Objective: Previous studies have reported inconsistent relationships between thyroid function and blood pressure (BP) levels. We aimed to explore the associations between thyroid hormone sensitivity and BP parameters.
Methods: This retrospective study included 6272 participants who underwent a health examination at the First Hospital of China Medical University between January 2017 and December 2018. The Thyroid Feedback Quantile-based Index (TFQI), Parametric TFQI, thyroid-stimulating hormone index, and thyrotroph thyroxine resistance index were calculated to reflect thyroid hormone sensitivity. Mean arterial pressure, pulse pressure, and rate-pressure product were used to indirectly represent arterial stiffness.
Results: The TFQI was positively associated with systolic BP (β = 3.22), diastolic BP (β =2.32), and mean arterial pressure (β = 2.62) (P < .001, for all). Analyses of the Parametric TFQI, thyroid-stimulating hormone index, and thyrotroph thyroxine resistance index yielded similar results. The TFQI was positively related to pulse pressure and rate-pressure product. With a 1 SD increase in the TFQI, the adjusted odds ratio for hypertension was 1.11 (95% CI 1.04-1.18). When comparing the fourth quartile of the TFQI with the first, the odds ratio for hypertension was 1.27 (95% CI 1.07-1.51, P _{for trend}  = .006). These relationships remained significant when stratified by age, sex, and body mass index. Similar results were observed in a euthyroid or normotensive population.
Conclusion: The TFQI was positively associated with BP and markers of arterial stiffness. Impaired thyroid hormone sensitivity was related to increased risk for hypertension.
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