Diagnosis of Feline Hyperthyroidism Using Thyroid Scintigraphy.

Marsolais M.E., Mott J. and Berry C.R.

Conference Proceedings, (2003). American College of Veterinary Internal Medicine: p.393

Diagnosis of hyperthyroidism is traditionally made by demonstrating elevations in the serum thyroxine (T4) level; however, fluctuations in T4 levels and the possibility that concurrent disease can suppress thyroid hormone concentrations often limit the diagnostic accuracy of this test. Hyperthyroidism has been definitively diagnosed by demonstrating a thyroid to salivary gland (T:S) ratio greater than 1:1 using sodium.