Repeat Radioiodine Injection For Hyperthyroidism

[GingerBear]

Has anyone had a cat that required more than one I-131 treatment for hyperthyroidism?

Background: Anna (12 yo) was diagnosed in September. She did well on methimazole for a few weeks, then I decided the radioiodine treatment was the way to go. That was done in early December. Unfortunately, her 4 week checkup revealed still high T4 numbers. I was told this was a possibility considering her high numbers to start. We need to wait on her 3 month blood test first, but it's likely a second round will be recommended. I will certainly talk with the radiation vet if it comes to it, but she's hard to get in touch with, so I wondered if the collective wisdom here had ever experienced this. How did the cat handle it? Any extra risks involved? I haven't been able to find much information other than it's not common. Of course! She didn't have many of the common symptoms either, so why not.

 

[FeebysOwner]

Hi. I don't have any personal experience with this, but I believe I have read that there is usually at least 3 months, sometimes 6 months, after treatment - to check levels - before considering a second treatment. Should that give you any consolation...

I hope other members on this site will soon see your post and offer first hand what their experiences have been! Hang in there!!

 

[kittyluv387]

Did your cat get a thyroid scintigraph before the first iodine treatment?

 

[GingerBear]

No, I don't think a scintigraph was done. She had chest xrays, but that was just to rule out heart or other issues before treatment.

 

[kittyluv387]

Well I would definitely have that done this time around before the radioactive treatment. They will be able to determine more accurately how much radioiodine your cat needs. It honestly should have been done the first time.

Do Hyperthyroid Cats Always Need a Thyroid Scan? | Animal Endocrine Clinic

 

[GingerBear]

Well I would definitely have that done this time around before the radioactive treatment. They will be able to determine more accurately how much radioiodine your cat needs. It honestly should have been done the first time.

Do Hyperthyroid Cats Always Need a Thyroid Scan? | Animal Endocrine Clinic

Yes, I'm kicking myself a bit for that. I'd read about it while researching, but with everything else going on it went right out of my mind. The radio clinic is the most convenient by far and was highly recommended, so I went with it. Thanks for the reminder! I will ask if things aren't improved by 3 months.

 

[crunchie]

I don't really have any first hand experience but I know that the clinic that I took my cat to has a policy that if the HT reappears within 1 year of treatment they will retreat the cat free of charge. Luckily all of her blood work was good (tested 1mo, 3mos and just shy of 1 year).
So I don't think it's common but not unheard of. From my understanding it would be more common with cat's who HT levels were very high to begin with.

 

[kittyluv387]

Yes, I'm kicking myself a bit for that. I'd read about it while researching, but with everything else going on it went right out of my mind. The radio clinic is the most convenient by far and was highly recommended, so I went with it. Thanks for the reminder! I will ask if things aren't improved by 3 months.

I'm sorry. Your veterinarian or the other professionals should have really encouraged you to get that done first.

 

[GingerBear]

Hi! I thought I'd give an update, in case anyone ever has a similar experience. Unfortunately, Anna did need to have a second I-131 treatment done. She started with T4 of 18.4 and dropped to 9.9 by 4 months. Still too high. Her second treatment was in March, and she handled it just fine, other than an epic poo in the crate on the way home. First time she's ever done that- of all the times! I worried when her 1 month T4 was still elevated, but she had her 3 month blood work this week, and we're back into an acceptable range- 2.1! I'm so relieved!