The T4 Test

Submitted by Veterinary Wellness Partners on Thu, 06/05/2014 - 9:35am

Thyroxin (T4) Testing

One of the more common tests that we run is the Thyroxine (T4) screening test.  This test is a generalized screening for both hypothyroidism (in dogs and horses) and hyperthyroidism (in cats).  Oftentimes, the T4 testing is paired with a complete blood cell test and the biochemical profile.  These three tests are often considered a baseline screening, especially in senior pets.  

A low value on the T4 test usually confirms hypothyroidism.  Occasionally we see a low value in debilitated animals.  In this case, the low value may be a condition called Euthyroid Sick Syndrome. This is a condition in which the Thyroxine (T4) levels are low due to the other disease process that is ongoing within the pet.  Animals with low thyroid levels can be easily supplemented and typical respond favorably to treatment.

A high value is a confirmation of hyperthyroidism.  This condition is common in cats.  Cats can be treated with medication to counteract the elevated thyroxine levels.  There are several methods to treat and each can be discussed with you, should you cat develop overactive thyroid disease.

For more information about the two conditions, please click on the embedded links, or search our website.