It is also possible for a cat to have a thyroid nodule that does not secrete excess thyroid hormone so a blood test must be done to confirm the diagnosis. In most cases, hyperthyroidism is relatively easy to confirm with a blood test. The only time diagnosis may be difficult is early in the disease because the T4 level will move in and out of the normal range over the course of the day. Like all hormones the blood level is not constant during the day. So, it is possible to take the blood sample when the level is at it's lowest point, which in early cases may still be within the normal range.
Hyperthyroidism is a treatable disease.
There are several different treatment options, and the preferred treatment will depend on the individual cat involved. Hyperthyroidism can be controlled, but not cured, with medication. These drugs block the production of thyroid hormones by the thyroid gland. These medications need to be given daily. Hyperthyroidism returns soon after the drugs are stopped.