The SCH prevalence rate was higher among women with hypertension, at 28%, compared with 20% among normotensive women. Among men, the prevalence of SCH was 21% among those with hypertension and 13% among the normotensive men.
Hypertension rates are increasing; it potentially affects up to 28% of the Chinese population.
People with SCH often lack obvious signs and symptoms, making it easy to miss.
Elevated blood pressure is positively correlated with thyroid-related diseases, but few studies have investigated the prevalence of SCH among persons with hypertension.
Prior study results documented a close relationship between SCH prevalence and hypertension, but the pathogenic relationship between the two is not clear.
This was a cross-sectional, observational study of 2818 randomly selected adults from Gansu Province, China.
The authors defined hypertension as a blood pressure of at least 140/90 mm Hg, normotension as a blood pressure of less than 120/80 mm Hg, and high normal blood pressure as pressures between these values.
They defined persons with SCH as those with normal levels of free thyroxine and free triiodothyronine and an abnormally elevated level of thyroid-stimulating hormone (TSH).
Among the 2818 people studied, 21% had hypertension, 43% had high normal blood pressure, and 36% were normotensive. The overall prevalence of SCH was 21%.
The prevalence of SCH was significantly higher among those with hypertension, 24%, than among those with normal blood pressure, 17%, regardless of age.
The prevalence of SCH was significantly higher in women than men in the normotensive, high-normal, and hypertensive groups: 20% vs 13%, 28% vs 18%, and 28% vs 21%, respectively.
The prevalence of SCH in hypertensive persons aged 60 years or younger (86% of the total study population) was significantly higher than in the normotensive population: 29% compared with 18%.
In a multivariate analysis, increased heart rate was significantly linked with a lower prevalence of SCH among people with hypertension. Measures that were significantly linked with an increased prevalence of SCH in people with hypertension were increased levels of triglycerides, low-density lipoprotein cholesterol, TSH-receptor antibody, thyroglobulin antibody, and fasting plasma glucose.
There is uncertainty about how well a single measure of a person's TSH level accurately reflects thyroid function.
The study received no commercial funding.
None of the authors had disclosures.