title: Subclinical thyrotoxicosis and the heart.
abstract: Subclinical thyrotoxicosis is defined as a below normal thyrotropin (TSH) in association with a normal total and free thyroxine (T4) and triiodothyronine (T3). It may be caused by thyroid hormone treatment or by endogenous thyroid disease. The degree of thyrotoxicosis may be estimated by the level of TSH suppression. Subclinical thyrotoxicosis may be associated with changes in cardiac performance and morphology, but this has not been consistently found in all patient populations. Changes may include increased heart rate, increased left ventricular mass index, increased cardiac contractility, diastolic dysfunction, and the induction of ectopic atrial beats or arrhythmias. Cardiac exercise performance may be impaired. Subclinical thyrotoxicosis should be treated in patients with cardiac symptoms or disease. Treatment may include reduction of the thyroid hormone dose, treatment of the underlying thyroid condition, or beta-blockers.
authors.affiliation: Division of Endocrinology & Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. LynnBMD@aol.com
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Burmeister
authors.forename: Angel
authors.initials: A
authors.lastname: Flores
mesh_terms: D009202:Cardiomyopathies / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D002320:Cardiovascular Physiological Phenomena; D017079:Exercise Tolerance / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006801:Humans; D013971:Thyrotoxicosis / Q000097:blood / Q000150:complications* / Q000628:therapy; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use; D016277:Ventricular Function, Left / Q000502:physiology; D018879:Ventricular Premature Complexes / Q000097:blood / Q000209:etiology / Q000503:physiopathology
chemical_list: D013972:Thyrotropin; D013974:Thyroxine