Introduction
Hyperthyroidism in cats is diagnosed based upon the cat’s symptoms, physical examination, and blood tests. In some cases, a technique called thyroid scintigraphy, or thyroid imaging, is used to detect how much of the thyroid has been affected by the disease.
Diagnosing Hyperthyroidism in Cats
Physical Examination
Hyperthyroidism causes a common series of symptoms to occur in cats, and many veterinarians begin their hyperthyroidism diagnosis based upon the cat’s symptoms. A physical examination of the thyroid gland may also help with the diagnosis. The thyroid gland consists of two lobes which are located on each side of the cat’s trachea. Lobes that have increased in size can usually be palpated by the veterinarian.
Blood Tests
Blood tests are often used to help confirm a hyperthyroidism diagnosis, but the results of the blood tests must be used in addition to a physical exam and pet history for an accurate hyperthyroidism diagnosis. Cats that have hyperthyroidism often have increased levels of T4, and sometimes T3, hormones circulating in their blood stream. The levels of T4 in the blood are tested in most cases as the T3 levels are only elevated in about 25% of cats with hyperthyroidism. Some cats with mild cases of hyperthyroidism have normal blood test results, and this is why blood tests cannot be used alone to diagnose hyperthyroidism.
Thyroid Imaging
In some instances, thyroid imaging is used in the diagnosis of hyperthyroid cats. This technique is only available at certain veterinarian facilities, and it is usually only performed in cases where the hyperthyroidism is caused by a cancer, or in cases where veterinarians wish to see how much of thyroid gland has been affected by the disease.