Gender-specific associations between subclinical hypothyroidism and blood pressure in Chinese adults

Hypothyroidism is often related with increased blood pressure, yet, gender-specific associations between subclinical hypothyroidism (SCH) and hypertension have not been previously assessed. We conducted a large-scale, cross-sectional study from six districts of Jiangsu Province to investigate the association of SCH and blood pressure in female and male adults. In the studied population, 4725 participants (3034 women and 1691 men) aged 20-60 years were included. The prevalence of hypertension was significantly higher in males as compared to females (37.34% vs. 27.39%, P < 0.05), while the prevalence of SCH was much higher in women (9.36% vs. 5.32%, P < 0.05). Furthermore, the hypertension rate was significantly higher in female SCH group compared to euthyroid (EUT) group(P < 0.05), while no significant differences were observed between the two groups in male participants(P > 0.05). After adjusting for age and body mass index (BMI), SCH was an independent predictor for increased SBP (OR = 1.47, 95%CI 1.08-1.99, P = 0.015) and elevated pulse pressure (OR = 1.45, 95%CI 1.05-1.99, P = 0.024) in females, and serum thyroid stimulating hormone (TSH) was significantly higher in female hypertensive group as compared to normotensive group (2.09 vs. 1.92 mIU/l, P = 0.0004). In male participants, SCH was not independently correlated with blood pressure, and no significant difference in TSH levels between hypertensive and normotensive groups was observed (1.74 vs. 1.66 mIU/l, P = 0.12). We concluded that SCH is an independent predictor of increased SBP and pulse pressure in females. Thus, thyroid function may influence blood pressure to a greater extent in females compared to males.