Radioiodine (I-131) Referral Checklist for Veterinarians



To provide the best medical service possible to pets with feline hyperthyroidism and their owners, we require a preliminary work-up on each patient prior to treatment. A clear picture of the overall health of each cat is critical in determining if it is an appropriate candidate for the treatment.

Here's What We Need

  • Laboratory blood tests (CBC, chemistry profile and T4 results) within 4 weeks prior to I-131 treatment
  • Urinalysis within 4 weeks prior to I-131 treatment
  • Thoracic radiographs (Lateral and VD) within 4 weeks prior to I-131 treatment
  • Echocardiogram (this can be performed within 4 weeks prior to I-131 treatment or done at NorthStar VETS on the day of treatment)
  • Cats must be off thyroid medication (tapazole, methimazole) for at least 14 days prior to I-131 treatment and a T4 must be done (after being off medication for 10 to 14 days) to ensure proper dosing of I-131.
  • If a cat has begun thyroid medication, please repeat the blood work and USG prior to discontinuing the medication (to ensure they are not azotemic or isosthenuric when they are euthyroid)
  • The New Jersey Department of Environmental Protection allows us to release cats treated with I-131 therapy 72 hours post-treatment provided their radiation levels measure low enough (0.5 mr/hr or below). Some cats may require an additional 24 hours of hospitalization to allow radiation levels to dissipate.

Additional Information

  • Please advise your clients to call and speak with one of our Internal Medicine technicians to schedule an appointment and obtain an estimate for treatment
  • Please fax all records and email radiographs (if possible)
  • Clients may also bring records and radiographs if faxing and emailing are not an option

Please call us with any questions at 609.259.8300.