Irwin Klein, MD, and his colleague Sara Danzi, PhD, investigate the cellular and molecular mechanisms of thyroid hormone action on the heart and cardiovascular system. Thyroid hormone exerts profound effects upon the heart and cardiovascular system. In order to understand the cellular and molecular events that underlie these effects, we conduct clinical and laboratory studies designed to elucidate the mechanisms by which thyroid diseases alter cardiac performance, and how thyroid hormone treatments can improve the function of the pathologic cardiovascular system. Thyroid hormone regulates the expression of many important genes expressed in the myocardium, and can significantly alter cardiac function.
 
Thyroid hormone metabolism can be altered in patients after cardiac surgery, following acute myocardial infarction and in heart failure. This low serum T3 level accompanying non-thyroidal illness is referred to as the low T3 syndrome. Recent studies, including work done in our laboratory, suggest that the heart is sensitive to moderate decreases in serum T3 levels and that the mammalian myocardium responds directly to decreased T3 levels by altering cardiac specific gene expression which in turn influence myocyte contractile function. The laboratory is currently studying the cardiomyocyte specific changes in gene expression that occur in low T3 states. Carefully monitored T3 replacement therapy in addition to the established treatment regimes available may provide improved cardiac function to a patient population with chronic disease and a poor prognosis.
 
Dr. Klein is Professor of Medicine and Cell Biology at NYU School of Medicine and Associate Chairman of the Department of Medicine at North Shore University Hospital. He currently serves as the Chairman of the American Thyroid Association Research Committee and is on the editorial boards of the Journal of Clinical Endocrinology and Metabolism, Endocrinology, Thyroid and Clinical Endocrinology. He has a long standing clinical and basic science interest in the mechanisms of thyroid hormone action on the heart and the potential role for novel thyroid hormone based therapies in the treatment of heart failure.