[Thyroid hormone and the cardiovascular system].

Thyroid hormone has many effects on the heart and vascular system. In hyperthyroidism changes in cardiovascular hemodynamics explain many of the clinical manifestations induced by thyroid hormones. In hypothyroidism the cardiovascular effects are opposite to those observed in hyperthyroidism, although the clinical manifestations are less obvious. This review will focus on the cardiovascular system in hyperthyroidism and hypothyroidism. In particular the subclinical dysfunctions of the thyroid gland, which occurs especially in older age, will be discussed. The clinical relevance and the necessity of diagnostic and therapy in subclinical thyroid disease are not clarified yet. In the United States an expert group has published a scientific review and guideline for the diagnosis and management of subclinical thyroid disease in 2004, which will also be outlined.