Association between Blood Pressure and Serum Thyroid-Stimulating Hormone Concentration within the Reference Range: A Population-Based Study

Abstract

The association between thyroid function and blood pressure is insufficiently studied. The objective of the investigation was to study the association between TSH within the reference range and blood pressure. This was a cross-sectional, population-based study. A total of 30,728 individuals without previously known thyroid disease were studied. The main outcome measures were mean systolic and diastolic blood pressure and pulse pressure and odds ratio for hypertension (>140/90 mm Hg or current or previous use of antihypertensive medication), according to categories of TSH. Within the reference range of TSH (0.50-3.5 mU/liter), there was a linear increase in blood pressure with increasing TSH. The average increase in systolic blood pressure was 2.0 mm Hg [95% confidence interval (CI) 1.4-2.6 mm Hg] per milliunit per liter increase in TSH among men, and 1.8 mm Hg (95% CI 1.4-2.3 mm Hg) in women. The corresponding increase in diastolic blood pressure was 1.6 mm Hg (95% CI 1.2-2.0 mm Hg) in men and 1.1 mm Hg (95% CI 0.8-1.3 mm Hg) in women. Comparing TSH of 3.0-3.5 mU/liter (upper part of the reference) with TSH of 0.50-0.99 mU/liter (lower part of the reference), the odds ratio for hypertension was 1.98 (95% CI 1.56-2.53) in men and 1.23 (95% CI 1.04-1.46) in women. Within the reference range of TSH, we found a linear positive association between TSH and systolic and diastolic blood pressure that may have long-term implications for cardiovascular health.