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Scintigraphy for Feline Hyperthyroidism

Harvey, A. M., A. Hibbert, et al. (2009). “Scintigraphic findings in 120 hyperthyroid cats.” Journal of Feline Medicine & Surgery 11(2): 96-106.

The purpose of this study performed at the University of Bristol, United Kingdom, was to characterize the scintigraphic findings in a group of cats with hyperthyroidism to determine the location of the abnormal thyroid tissue. Thyroid scintigraphy relies on the selective uptake of a radionuclide by thyroid tissue. Hyperthyroidism is diagnosed by the increased level of uptake by the thyroid gland compared with salivary gland tissue. Thyroid scintigraphy also demonstrates the location of the abnormal thyroid tissue, which is useful when planning treatment options. The database of the Feline Centre at the University of Bristol was searched for cases of feline hyperthyroidism with good quality scintigraphic images between 1994 and 2007. Images from 120 cats were evaluated. Almost 1 in 5 hyperthyroid cats was found to have multiple areas of abnormal thyroid tissue and/or intrathoracic thyroid tissue where surgical thyroidectomy would not be curative. Another finding was that scintigraphy could not reliably differentiate between thyroid carcinoma and adenoma. The authors conclude that the possible presence of ectopic thyroid tissue should be discussed with all owners of hyperthyroid cats prior to performing surgical thyroidectomy. [SL]
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Related articles:
Henrikson, T. D., L. J. Armbrust, et al. (2005). “Thyroid to salivary ratios determined by technetium-99m pertechnetate imaging in thirty-two euthyroid cats.” Vet Radiol Ultrasound 46(6): 521-3.
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Naan, E. C., J. Kirpensteijn, et al. (2006). “Results of thyroidectomy in 101 cats with hyperthyroidism.” Vet Surg 35(3): 287-93.
>> PubMed Abstract