title: Scintigraphic manifestations of thyrotoxicosis.
abstract: The term thyrotoxicosis refers to the clinical syndrome of increased systemic metabolism that results when the serum concentrations of free thyroxine, free triiodothyronine, or both are elevated. The term hyperthyroidism refers to overactivity of the thyroid gland with a resultant increase in thyroid hormone synthesis and release into the systemic circulation. These terms are not interchangeable, since thyrotoxicosis can develop in thyroid conditions that are not associated with increased thyroid function, such as thyroiditis, or in so-called factitious hyperthyroidism. The clinical signs and symptoms of thyrotoxicosis are virtually identical regardless of the cause. However, in a given patient, every attempt should be made to determine the exact cause of the thyrotoxicosis, as this in turn determines the prognosis and treatment. Since thyroid scintigraphy demonstrates the functional state of the thyroid gland, it should be used, in conjunction with determination of radioactive iodine uptake, as the imaging modality of choice for diagnosis of thyrotoxicosis. Although the scintigraphic features of several of the thyroid disorders that cause thyrotoxicosis may overlap, their recognition helps narrow the differential diagnosis, thereby guiding the referring physician in the work-up and management of this disorder.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, 861 Main Bldg, Philadelphia, PA 19107, USA. charles.intenzo@jefferson.edu
authors.forename: Charles M
authors.initials: CM
authors.lastname: Intenzo
authors.forename: Anne E
authors.initials: AE
authors.lastname: dePapp
authors.forename: Serge
authors.initials: S
authors.lastname: Jabbour
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Miller
authors.forename: Sung M
authors.initials: SM
authors.lastname: Kim
authors.forename: David M
authors.initials: DM
authors.lastname: Capuzzi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging / Q000379:methods*; D013971:Thyrotoxicosis / Q000175:diagnosis* / Q000000981:diagnostic imaging*