You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

The T3 Suppression Test is a useful test to perform in cats with suspected hyperthyroidism, but in which T4 concentrations are within the normal range.

In early cases of hyperthyroidism in cats T4 concentrations may be within the normal range but the disease is present. The normal range is 12-52 nmol/l.

Method :

1. Measure the concentration of T4 (thyroxine) in a blood sample  (plasma or serum)

2. Administer 7 doses of 20mg liothyronine at 8 hour intervals

3. 4 hours after the last dose measure T4 concentrations in the blood 

Results :

In hyperthyroid cats the T4 concentration is MORE than 50% of the pre-treatment level

In normal cats the T4 concentration is suppressed to LESS than 50%  of  the original pre-treatment concentration

Last updated : October 2013