Thyroid hormone within the normal range is associated with left ventricular mass in patients with hypertension

Thyroid hormone amplifies hypertrophy of cardiac myocytes. The heart is influenced by the minimal changes of thyroid hormone levels. We hypothesized that thyroid hormone within the normal reference range may be associated with left ventricular (LV) mass in hypertensive subjects. We performed echocardiography to assess LV mass indexed by body surface area (LVMI), and measured thyroid stimulating hormone (TSH), free triiodo-thyronine (fT3), free thyroxine (fT4), and brain natriuretic peptide (BNP) in 318 hypertensive patients without known thyroidal diseases. Glomerular filtration rate (GFR) was estimated using the MDRD formula. Relationship between each thyroid hormone and LVMI in hypertensive patients with euthyroidism were investigated using a multiple linear regression model entering age, gender, height, weight, GFR, log BNP, systolic BP, the use of more than 2 different types of antihypertensive medications, and HbA1c as covariates. Thyroid hormone and TSH levels were within the normal range in 293 patients. In these patients, fT3 (standard β = 0.13) and fT4 (standard β = 0.11) positively, and TSH (standard β = –0.15) inversely correlated with LVMI in the multiple linear regression model. Thyroid hormone may be associated with LV remodeling independent of renal and LV dysfunctions in hypertensive patients with euthyroidism.