I-131 Results

Radtech49

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Hi All,

My 15yo cat, Jack, had I131 treatment on Monday and I brought him home on wednesday. His dose was apparently a low one, so his radioactivity came down pretty fast. He is scheduled for bloodwork in about 30 days.
For anyone who's had this done, how long before you noticed an improvement? Trying to search for that answer has left me with no information except that it could be 1 month to 9 months. So, just looking for anecdotal stories from everyone to get a feel for what to look for. He's not eating very much, He's drinking a lot of water(which I attribute to him being at the hospital for 2 days and in the carrier, etc) and he's very vocal and restless. So basically the same as before the treatment.
I hesitated to treat him in this way because of his age, but he's a very spry 15yo and other than his thyroid, he seems to be in good health. I just wish this was caught earlier. We suspected it years ago, but his bloodwork and urine always came back normal and the hospitals near me won't treat solely on symptoms.
Anyway. I'm just hoping that he gets relief. He just always seems so stressed out and worried(for lack of a better word) and he's skinny. I imagine he burns every calorie from pacing half the day. Thanks for any info.
 

Catmom1234567890

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Hi there,
Was the I-131 for diagnostic dose or larger dosage for treatment to shrink overactive thyroid gland. The purpose of I-131 for thyroid ablation is to destroy the overactive thyroid gland. I-131 that is not absorbed by the thyroid gland is excreted via urine during the first couple of days. I-131 is still retained in the thyroid. Improvement takes time as I-131 is still working to ablate the thyroid gland.

If he is eating, using the litter box, and active, I would observe him as the med doesn't work right away. However, if he is breathing abnormally then I would take him to the vet asap.
 
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Radtech49

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Hi,
No, He's not panting or anything like that. Just wondering what other people's experiences were with the therapy and time of seeing a change. No masses, just overactive thyroid. I don't know the dose, they just said it was small
 

Catmom1234567890

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Hi,
No, He's not panting or anything like that. Just wondering what other people's experiences were with the therapy and time of seeing a change. No masses, just overactive thyroid. I don't know the dose, they just said it was small
It sounds like it was a therapeutic dosage. I-131 retained in the thyroid gland takes time to ablate, thus your vet wants to see you in 30 days for blood work. I-131 has a half life of 8 days. This means it takes 8 days to reduce the radioactivity in half. I'm not a vet, but I'm a radiochemist and used to compound I-131 for kitties and humans. Please do not take this as medical advice. You know your kitty when he's not feeling well. Follow your gut instinct.
 

Antonio65

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Hi R Radtech49 ,

My cat was treated with I-131 at the age of 16 years and 3 months. She was held at the facility for four days and then she came home with me. Her radioactivity level was safe for travelling, but I was advised to keep her in a separate room for 4 weeks, which I disregarded because I didn't want her to suffer more than she did already.
The first bloodwork was required 30 days post treatment, with Thyroid levels, Kidney levels, weight and significant clinical signs.
Same thing 90 days and 180 days post treatment.
These results had to be sent to the facility for their database.

For good measure I ran all the required tests at days 120 and 150, just to be safe.

The first slight clinical improvement appeared 3 months post treatment, and the improvement was very well visible the next month.
My cat had an apathetic form of HT, and she had a few other ailments, so I didn't see much difference in her daily behavior, but the bloodworks were clear on the fact that she was getting better.

So i don't think you'll be able to see any significant improvement before Christmas. I hope it is faster in your case, but my experience reflected what I was told at the facility, so I guess they told me that based on their long experience.
 

Antonio65

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Hi,
No, He's not panting or anything like that. Just wondering what other people's experiences were with the therapy and time of seeing a change. No masses, just overactive thyroid. I don't know the dose, they just said it was small
You should have received a report of the treatment your cat got. On that report they should say what kind of treatment he received, if he was scanned with scintigraphy, the dosage of I-131 they injected, and the residual radioactivity level upon releasing.
This is what I have.
 
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Radtech49

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You should have received a report of the treatment your cat got. On that report they should say what kind of treatment he received, if he was scanned with scintigraphy, the dosage of I-131 they injected, and the residual radioactivity level upon releasing.
This is what I have.
No facility near me uses scintigraphy
 

Antonio65

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No facility near me uses scintigraphy
OK, but the report should tell you the dosage of I-131 given and the level of radioactivity your cat had at the moment of discharge.
But I also understand that not all facilities work the same way.

EDIT:
The scintigraphy is an important scan taht should always be done before the I-131 injection because it's the only way to assess the correct dosage.
 

neely

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No facility near me uses scintigraphy
I'm sorry to hear this but I understand you wanting to proceed with the I-131 treatment to help your cat, Jack. 🤗

I understand why Antonio65 Antonio65 explained the scintigraphy is so important. We brought our cat who was diagnosed with H-T in for follow up bloodwork last week and I am in the process of scheduling his I-131 treatment. The first available appt. is Nov. 30 and I purposely chose a facility that offers the scintigraphy. I guess we are lucky the facility here requires it. They also keep the cat at their facility for longer than your cat was there. I honestly don't know if there is a set amount of days or not but since it is a university affiliated veterinary medical school/specialty center I trust their knowledge and expertise. They told me the procedure is to bring the cat in on Tuesday and they go home on Saturday. They require repeat bloodwork at 1 mo., 3 mos., 6 mos. and 1 year.

Like you, I have to admit I'm anxious and nervous about his health as well as being away from home for that length of time but know in my heart the I-131- is the best treatment for his Hyperthyroidism. I sincerely hope that Jack starts to show signs of improvement in his appetite and gains some weight. Please keep us posted on his progress. :alright:
 
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Radtech49

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What's maddening is that we have a top notch veterinary school here, but their Hyperthyroid treatment center has never reopened since the whole covid thing. Other areas are open, just not this one. Makes me so angry. The only other places in driving distance don't do the scintigraphy.
 
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Radtech49

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OK, but the report should tell you the dosage of I-131 given and the level of radioactivity your cat had at the moment of discharge.
But I also understand that not all facilities work the same way.

EDIT:
The scintigraphy is an important scan taht should always be done before the I-131 injection because it's the only way to assess the correct dosage.
Yeah, i would have chosen that if it was available. The veterinary school that did offer that has closed their hyperthyroid section of the hospital down since covid hit and have never reopened. Really makes me angry.
His dose was 3.49mci. His dose at discharge was low enough that i didn't have to save his poop.
 
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