Blood pressure levels in patients with subclinical thyroid dysfunction: a meta-analysis of cross-sectional data

The relationship between subclinical thyroid dysfunction and blood pressure is controversial and has received insufficient attention. The aim of this study was to assess whether blood pressure levels in patients with subclinical thyroid dysfunction differ from those of euthyroid subjects. A meta-analysis of all cross-sectional studies was performed to compare the blood pressure levels in patients with subclinical thyroid dysfunction with those of healthy controls. A computer-based online retrieval of databases (MEDLINE and EMBASE) and manual searches were undertaken to identify articles that addressed the association between subclinical thyroid dysfunction and blood pressure levels and were published through 2010, using no language restrictions. The meta-analysis was performed using STATA 11 (Stata). Seven cross-sectional studies were examined. In patients with subclinical hypothyroidism, the pooled estimate of the weighted mean difference (WMD) of increased blood pressure revealed a significant difference in both systolic blood pressure (SBP; WMD with 95% confidence interval (CI) 1.89 mm Hg (0.98-2.80), P<0.05) and diastolic blood pressure (DBP; WMD with 95% CI 0.75 mm Hg (0.24-1.27), P<0.05). However, in patients with subclinical hyperthyroidism, the pooled estimate of the WMD of increased blood pressure revealed no significant difference in SBP (WMD with 95% CI -0.75 mm Hg (-1.81 to 0.31)) or DBP (WMD with 95% CI -0.64 mm Hg (-2.36 to 1.08)). The present meta-analysis indicates that subclinical hypothyroidism is associated with increased SBP and DBP, whereas subclinical hyperthyroidism is not. Further investigation is needed to confirm blood pressure levels in patients with subclinical thyroid dysfunction. Hypertension Research (2011) 34, 1098-1105; doi:10.1038/hr.2011.91; published online 28 July 2011