Relationship between thyroid function and elevated blood pressure in euthyroid adults

Thyroid hormones (THs) have profound effects on cardiovascular functions, suggesting that THs may contribute to the development of elevated blood pressure (BP). Few studies, however, have systematically assessed the relationship between THs and elevated BP. We therefore conducted a cross‐sectional study to examine how serum THs concentrations are related to the prevalence of elevated BP in a euthyroid population. This study (n = 12 487) was performed in Tianjin, China. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid‐stimulating hormone (TSH) levels were measured by chemiluminescence immunoassay. Elevated BP was defined according to the JNC 8 criteria. Analysis of covariance and multiple logistic regression models were used to assess the relationships between FT3, FT4, and TSH quartiles and elevated BP. The multivariable‐adjusted odds ratios (95% confidence interval) of elevated BP for gradual increase in the FT3, FT4, and TSH quartiles, when compared to the lowest quartiles were 1.08 (0.97, 1.21), 1.24 (1.12, 1.39), and 1.32 (1.18, 1.47); 1.18 (1.06, 1.32), 1.18 (1.06, 1.31), and 1.24 (1.11, 1.38); 1.06 (0.96, 1.19), 1.06 (0.95, 1.18), and 1.03 (0.93, 1.15), respectively. Our study demonstrated that FT3 and FT4 are positively related to the prevalence of elevated BP in euthyroid adults, but no significant relationship was found between TSH and elevated BP.