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Dr. B.
Dr. B., Cat Veterinarian
Category: Cat
Satisfied Customers: 20578
Experience:  I am a small animal veterinarian with a special interest in cats and am happy to discuss any questions you have.
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I have a cat who has very high over active thyroid. What is

Resolved Question:

I have a cat who has very high over active thyroid. What is normal, and what is abnormally high?
Submitted: 2 years ago.
Category: Cat
Expert:  Dr. B. replied 2 years ago.

Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.

Was your cat's blood work tested at the vet pratice or sent to the lab for testing?

Customer: replied 2 years ago.
The blood test was done at a vet who sent it on to a lab for testing.
Expert:  Dr. B. replied 2 years ago.
Thank you,

First, I have to note that the exact reference range does vary by lab. Still, the range used by the lab that tested your cat's blood should be listed on the report they sent to your vet. Generally speaking though, a normal thyroid level is 20 - 40 nmol/L (or 1.2-5.2 ug/dL). Anything over this level would be considered high and therefore positive for hyperthyroid.

Now when we call a thyroid level "very high," this usually means that the level on the test was so elevated that the machine could not detect it. And while that may initially sound worrying (when we consider that higher = worse for other parameters), this is not necessarily any worse then a slightly elevated level. This is because different cats will respond to the various treatments (ie medication, dietary treatment with Hills Y/D, radioactive iodine, surgery, etc) differently. So, even if his thyroid levels were terribly high, it is quite possible to see those drop into normal range when initial treatment is started. Of course, it is also possible (as it is for any hyperthyroid cat) that your wee one may need his treatment dose adjusted to get him to a stable normal level.

I hope this information is helpful.

If you need any additional information, do not hesitate to ask!

All the best,

Dr. B.

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If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need as this is how I am credited for assisting you today. Thank you! : )
Customer: replied 2 years ago.
Thanks for reply, but I'm none the wiser really. The vet told me the cat's over active thyroid was 170, which was nearly off the scale as she said. I have been given tablets for the cat which are £73 per month! Is this normal?
Expert:  Dr. B. replied 2 years ago.
You are very welcome,

As you can see from my aforementioned reference range, that is very high. But again, I have seen cats in the high 100's drop into normal range even on a low dose of medication, so the key will be to treat and see where the thyroid level is in a few weeks time.

Now since that does sound oddly expensive, can you tell me which tablets you were given (ie Vidalta, Felimazole, etc)?
Customer: replied 2 years ago.
The tablets are 15 mg Vidalta carbimazole and Denamarin to suppoirt the liver, each tablet contains Silybin A+B 9mg.
Expert:  Dr. B. replied 2 years ago.
Hi again,

Well, if your cat is also on Denamarin (which is for liver troubles), this will raise costs quite a bit. Still, to keep costs down, I would note that you can consider requesting that your vet write a prescription so that you can purchase the medication online. As the online pharmacies are large companies, they can often sell these medications at reduced cost. You can see examples of costs for the Vidalta here (ie Viovet & PetDrugsOnline. ) As well, the cost of Denamarin (ie Viovet) may also be better via an online pharmacy and often doesn't require a prescription (since its a supplement and not a drug).

So, both drugs together would certainly raise monthly costs, but to keep costs down you could consider the above options or see if your vets offer a price match.

All the best,

Dr. B.

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If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need as this is how I am credited for assisting you today. Thank you! : )

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