Subclinical hypothyroidism and hypertension in relation to thyroid cysts: A cross-sectional study

Abstract

Subclinical hypothyroidism is a condition characterized by a normal range of thyroid hormone [triiodothyronine (T₃) and thyroxine (T₄)] but with an elevated level of thyroid stimulating hormone (TSH) . It is also reported to be associated with hypertension. Since thyroid cysts could have a beneficial effect on the activation of thyroid hormone as reported in our previous study, their presence could influence the association between subclinical hypothyroidism and hypertension. To clarify those associations, a cross-sectional study of 1,724 Japanese within normal range of thyroid hormone (i.e., normal range of free T₃ and free T₄), aged 40-74 years, who participated in an annual health checkup in 2014 was conducted. Among the study population, 98 were diagnosed as having sublicnical hypothyroidism. For participants without a thyroid cyst, hypertension had a significant positive association with subclinical hypothyroidism, while for participants with a thyroid cyst, even though the power could not reach a significant value, an inverse tendency between hypertension and subclinical hypothyroidism was observed. The adjusted odd ratios (ORs) and 95% confidence intervals (CIs) were 1.91 (1.08, 3.37) for participants without thyroid cysts and 0.63 (0.26, 1.55) for participants with thyroid cysts, respectively. The status of thyroid cysts could act as a determining factor in the association between subclinical hypothyroidism and hypertension among participants within normal range of thyroid hormone.