Dr. Mann’s 6-year-old daughter’s
rendering that lead to the naming
of The Cat Company and which
provided the inspiration for the
color scheme of our web site.

How is Feline Hyperthyroidism Diagnosed?

First, you and your vet should look for changes in your cat’s behavior. These might include any or all of the following:

  • Weight loss
  • Anxiety or nervousness
  • Excessive appetite or decreased appetite
  • Increased water intake
  • Hyperactivity or lethargy
  • Excessive shedding, hair loss poor coat condition
  • Diarrhea or vomiting
  • Increased urination
  • Cardiac symptoms - rapid heart rate, arrhythmia

Normally the thyroid gland cannot be felt in your cat’s neck, but in some cases of hyperthyroidism the gland becomes large enough to feel.

Since many of the signs of hyperthyroidism can also be found in other diseases such as diabetes mellitus, kidney failure, heart disease, or liver disease, laboratory tests such as a CBC, serum chemistry, and urinalysis are generally performed to determine if these diseases are present.

The total T4 or simply T4 is the best and most common test used to diagnose hyperthyroidism in your cat.  Sometimes, veterinarians will use other tests to confirm their diagnosis of hyperthyroidism. These include the T3 suppression test, thyrotropin-releasing hormone stimulation test, measurement of free T4, and thyroid radionuclide uptake and imaging.