Long-Term Thyrotropin-Suppressive Therapy with Levothyroxine Impairs Small and Large Artery Elasticity and Increases Left Ventricular Mass in Patients with Thyroid Carcinoma

Background: Exogenous subclinical hyperthyroidism, caused by long-term thyrotropin (TSH)-suppressive treatment with levothyroxine (LT4), is associated with several cardiovascular abnormalities. In order to assess the effect of long-term thyroid hormone-suppressive therapy on the blood vessels and myocardium, we determined the arterial elasticity, using the pulse wave contour analysis. Methods and results: Twenty-six athyreotic patients receiving TSH-suppressive LT4 therapy for periods ranging from 3 to 21 years at a mean daily dose of 2.25 ± 0.5 µg/kg per day were included in the study. Twenty six age- and gender-matched healthy subjects served as controls. Arterial elasticity of large and small arteries was evaluated using pulse wave contour analysis method (HDI CR 200, Eagen, MN). Cardiac structure was assessed by two-dimensional echocardiography. We found decreased large artery elasticity in subclinical hyperthyroidism (sHT) patients compared to controls (14.14 ± 3.38 versus 10.53 ± 2.43 L/mm Hg × 100,...