Questions on T4 levels, Hyperthyroidism and I-131 Treatment

catmando2

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Have a few questions about the T4 levels, Hyperthyroidism and I-131 Treatment.

I know before I-131 treatment, often cat get treated with meds (thermal gel or pill) and that's stopped about 7-14 days before the I-131 treatment.

My questions are how important is it that the T-4 levels are down to about normal range before the I-131 treatment? Yes, I understand if a cat is showing signs of hyperthyroidism we wish to treat them to get them more stable while waiting for the I-131 treatment.

For example, say a cat has a very high T4 and takes meds and cuts the T4 level down but still a bit high. Wouldn't at the time of the I-131 treatment, wouldn't the treatment take care of and probably cure the hyperthyroidism regardless if the T4 levels were in good range or not? If not, then what am I missing?
 

neely

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There are several steps before a cat can receive the I-131 treatment. They need to be considered a good candidate which is determined by a thorough physical exam, T-4 test, two view thoracic x-rays, CBC, blood pressure and urine analysis within one month of the procedure. If you have questions about your cat qualifying for the treatment I would suggest consulting with your vet or contacting a radiologist at the facility where you would go and ask if they do Scintigraphy which is essential.

Our cat was initially on Methimazole in the transdermal gel form after being diagnosed with Hyperthyroidism. Our feline vet told us he was a good candidate for the I-131 because he had no organ involvement so we looked into the radioactive iodine treatment. Best of luck.:crossfingers: I hope you are able to look into the procedure for your cat.
 
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catmando2

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There are several steps before a cat can receive the I-131 treatment. They need to be considered a good candidate which is determined by a thorough physical exam, T-4 test, two view thoracic x-rays, CBC, blood pressure and urine analysis within one month of the procedure. If you have questions about your cat qualifying for the treatment I would suggest consulting with your vet or contacting a radiologist at the facility where you would go and ask if they do Scintigraphy which is essential.

Our cat was initially on Methimazole in the transdermal gel form after being diagnosed with Hyperthyroidism. Our feline vet told us he was a good candidate for the I-131 because he had no organ involvement so we looked into the radioactive iodine treatment. Best of luck.:crossfingers: I hope you are able to look into the procedure for your cat.
Thanks. I undestand about the cat needing a bunch of labs to show the cat is a candidate for I-131. But still doesn't answer my question. Say if the cat is healthy all around but at time of I-131, the cat's T4 levels are high. Wouldn't that really not be an issue if high or good range at time since the I-131 should cure regardless (given, if the cat is healthy and good candidate and passed the tests)?
 

neely

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What is the age of your cat and how high is the T-4? I can only tell you that prior to our cat receiving the I-131 his T-4 was in the normal range. This is a question you should discuss with the vet who diagnosed the Hyperthyroidism since we can not give medical advice. Sorry.
 

FeebysOwner

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I think the key is that the cat obtains what they call 'euthyroidism' - meaning within the acceptable range - and that is when they would qualify to go through all the various follow up prep-testing for I-131 treatment. The thing I am not sure about is how long they have to maintain that state. That could vary by specialist to some degree.

The best I could find is this link (see under the section labeled "Preparation") - Radioactive Iodine Treatment (I-131) For Cats - Cat-World

Do you know who/what group you will be dealing with for the I-131 treatment? As neely neely suggested above, that is who I would ask about the timing and acceptable range.
 
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catmando2

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I think the key is that the cat obtains what they call 'euthyroidism' - meaning within the acceptable range - and that is when they would qualify to go through all the various follow up prep-testing for I-131 treatment. The thing I am not sure about is how long they have to maintain that state. That could vary by specialist to some degree.

The best I could find is this link (see under the section labeled "Preparation") - Radioactive Iodine Treatment (I-131) For Cats - Cat-World

Do you know who/what group you will be dealing with for the I-131 treatment? As neely neely suggested above, that is who I would ask about the timing and acceptable range.
I'm not to that point yet as the appointment is still a few months away.

Am just trying to understand as the I-131 brochures seem to say one shot and you are done .. a cure. So that perked my curiosity. Namely, if there's more to it than that, like the tests and T4 levels at time of shot?
 

FeebysOwner

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I think there is way more to it than what you just suggested - there is a process, and there should be more information that can be given to you than just an introductory brochure.

This web site is a hard one to navigate, but it might be worth your time to poke around in it to get a clearer picture of what is entailed.
Animal Endocrine Clinic | Where science and compassion cure
 
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catmando2

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Had a call back from a vet at the animal hospital I take my cat to. The vet was following up with a letter they got from the I-131 cat hospital that will be doing the treatment for my cat in Dec. The discussion also was about a letter I sent to another vet there at the animal hospital who saw my cat recently. The place plays a bit of musical chairs as to which vet I have. One that left, then another and now one that who had prescribed the most recent meds.

Anyhow, when talking we both kind of came to the same conclusion. Namely that at time of the I-131 treatment, the T4 levels at that time don't have to be perfect. In otherwords, I specially asks, "If the T4 levels are a bit high at the time, then it really isn't that critical right, as wouldn't the I-131 treatment take care of that?" The vet said, "Yes, it should" and mentioned because of that we really don't have to be too compulsive (my word not her's) about doing all the lab work that often. As long as he's healthy is the main thing.
 
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catmando2

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Another update ...

My cat's I-131 treatment appointment's moved up from 12/12 to 10/10.

Someone cancelled their appointment and the cat hospital doing the treatment said they have and opening and am I still interested in a sooner date. I sure am!

The sooner the better as for one, I wish to get him off the methamazole pill soon too as he is getting some side effects from the drug. Perhaps mild, but still makes me nervous.

He's scheduled to do all the pre-tests in about 2 weeks before treatment the week after.
 
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catmando2

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If your cat is scheduled on 10/10, it's already two weeks away. You should have all pre-tests done on next Monday.
Ask them when you have to stop the methimazole.
I had to stop it 6 days before the treatment.
According to the cat hospital that's doing the treatment, have to stop methimazole at least 7-14 days prior. Today is like 16 or 15 days prior. I told them I plan on stopping after today. As for the tests, they say have to stop med at least 7 days after cessation of meds. So test on 10/3 gives makes the cut off. I was thinking like you too and scheduled for Monday on 9/26 at first but they said no as has to be off the med before. Scheduling is like a jigsaw puzzle :alright:.
 

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Scheduling isn't the only jigsaw. Every facility has its own protocol.
Some don't need to have a test done a week prior to the injection, some hold the cat two weeks after the injection, and so on.

Also, it is highly advised to have a scintigraphy done shortly before the treatment. Most facilities run that test in-house.
When my cat was treated, they ran the scintigraphy a few minutes before giving her the shot.
Scintigraphy is important because it allows the vets to adjust the dosage of I-131 on the real needs of the cat.
 

neely

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Scintigraphy is important because it allows the vets to adjust the dosage of I-131 on the real needs of the cat.
I couldn't agree more and for this reason chose a veterinary specialty center that does Scintigraphy. :agree:

Good luck, we'll be thinking of your cat and you on October 10th. :goodluck:
 
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