Thyronorm not controlling hyper-T4?

RE: Thyronorm not controlling hyper-T4?

Robin Grimmer — Tue, 21 Nov 2017 11:16:48 GMT

I've inherited a case like this. Cat was doing fine on methimazole gel tubes topically, but the previous vet dedided the cat wasn't doing well on this and changed to Thyronorm 0.5ml bid without checking the T4 they then told the owner to give the Thyronorm with food contrary to the data sheet and when I saw it back to check bloods its T4 was now over 80 and the cat has lost weight the last recorded T4 was 6 months ago and was 52. I told the owner to give it without food and check again in a month but don't know how big a factor this is. I guess if still high will need a dose increase.

RE: Thyronorm not controlling hyper-T4?

Lucy Fleming — Tue, 21 Nov 2017 09:10:19 GMT

[quote user="Martin Atkinson"]Doh! Its because I was looking in old version of BSAVA formulary and it wasn't there and I misread the Google search. But just to add confusion Thyronorm tablets for humans contains levothyroxine and is of course for hypothyroidism![/quote]

Yeah I have to double check it every time!

And yes I spotted the human one as well when I was googling doing some research before putting my first case on it. The owner was getting it online as well so made sure to give her very careful instructions to be certain she was getting "Thyronorm for Cats"...!!

RE: Thyronorm not controlling hyper-T4?

Yantha Smyth — Sat, 18 Nov 2017 10:54:08 GMT

Hi I saw a cat for repeat T4 last week After dose increase; Initially it had been on 0.5ml bid, and its T4 was 257 at retest with good compliance. The dose was increased to 1ml bid (5mg bid) and 4wks later T4 was 21!

I would say increase dose and test again 3-4 weeks in your case.

Cheers

Yantha

RE: Thyronorm not controlling hyper-T4?

Martin Atkinson — Fri, 17 Nov 2017 18:36:58 GMT

[quote user="Lucy Fleming"]Thyronorm is methimazole (known as thiamazole though, the international nonproprietary name, apparently, while methimazole is the United States Adopted Name) - it isn't carbimazole.[/quote]Doh! Its because I was looking in old version of BSAVA formulary and it wasn't there and I misread the Google search. But just to add confusion Thyronorm tablets for humans contains levothyroxine and is of course for hypothyroidism!

RE: Thyronorm not controlling hyper-T4?

Lucy Fleming — Fri, 17 Nov 2017 16:53:29 GMT

I'm another one for increasing the dose - 0.5ml BID is the suggested starting dose, so increasing seems sensible to me. If still not doing well I would lean towards iodine treatment - I believe the boarding periods are quite a bit less now than they used to be, and cats are certainly well looked after when there! I had heard (but can't remember where from) that bioavailability might actually be better when in food but not been trialled - certainly as long as consistent shouldn't be making a big difference. Hopefully a bigger dose will sort the cat out!

[quote user="Martin Atkinson"]That said, I don't like Carbimazole I've never found it as reliable or as adjustable as methimazole[/quote]

Thyronorm is methimazole (known as thiamazole though, the international nonproprietary name, apparently, while methimazole is the United States Adopted Name) - it isn't carbimazole.

[quote user="Michael Woodhouse"]Board and medicate cat for a week. Re bleed and see.[/quote]

A week might not be long enough. Re-sampling normally suggested after three weeks.

I also agree that it might be a carcinoma, but just not a high enough dose seems more likely to me at the moment. Look forward to an update!

RE: Thyronorm not controlling hyper-T4?

Thomas Johnson — Fri, 17 Nov 2017 16:29:49 GMT

[quote user="salome2001"]

This is my first experience using Thyronorm.

the cat has been on it since diagnosed in February. Owner is convinced cat gets 95% of doses ("maybe missed 5 in 5 months") and is giving it in the mouth. She is a dedicated owner and I believe she is getting it in the cat :)

Currently on 0.5ml bid

the latest T4 is 174 nmol/L , and the cat clinically is tachycardic and has lost weight.

So... for anyone using Thyronorm more regularly... have you had any problems with efficacy?

[/quote]

I've got a few cats on it and have found it very effective, in your situation I would increase the dose to 1ml bid and see what happens.

RE: Thyronorm not controlling hyper-T4?

niall morton — Fri, 17 Nov 2017 15:18:30 GMT

I think Sarah caney offers thyronorm support for any difficult cases, shes very helpful so worth giving her a shout

RE: Thyronorm not controlling hyper-T4?

Rob Loxley — Fri, 17 Nov 2017 13:31:22 GMT

another fan of thyroidectomies here; generally no problems identifying the PT and can preserve in-situ in most cases or reimplant otherwise

RE: Thyronorm not controlling hyper-T4?

salome2001 — Fri, 17 Nov 2017 10:15:04 GMT

thanks all for input.

as I said, I do think the cat is receiving the medication.

I don't like thyroidectomies for all the reasons already mentioned above, its my last resort option.

I-131 is on the radar for the owner but she doesn't want to do it because of the boarding issue.

We have discussed y/d and as the hat is a solo homebody, it's our next option

But we are increasing the dose and rechecking in a few weeks.

(the cat also has some pre-existing mild renal issues)

thanks

RE: Thyronorm not controlling hyper-T4?

Martin Atkinson — Fri, 17 Nov 2017 10:02:35 GMT

[quote user="Beats"] Just take out the bigger gland - complete extracapsular if you don't plan on returning +/- cutting out the parathyroid and sticking it in neck muscle[/quote]This is assuming that you can identify the parathyroids in the first place. IME they are rarely anything other than a vaguely paler bit near the proximal pole and I have done dozens of them. It is then not straightforward to dissect out and/or preserve the blood supply especially if the thyroid is fragile and the capsule indistinct and there is no certainty that if you bury them in muscle they will survive. All good in theory but less so in practice.

RE: Thyronorm not controlling hyper-T4?

Beats — Fri, 17 Nov 2017 09:46:00 GMT

[quote user="Martin Atkinson"][quote user="Beats"]Either way I'd remove the thyroid.[/quote]Assuming its unilateral. It is not always possible to preserve the parathyroids even if you're an experienced surgeon and a hypocalcaemic cat is more problematic to monitor and treat than a hyperthyroid cat.[/quote]

I agree I like to feel the neck before deciding on options, however:

If bilateral, you still have plentiful options to improve things:

1) Just take out the bigger gland - complete extracapsular if you don't plan on returning +/- cutting out the parathyroid and sticking it in neck muscle

2) Staged removal 3 weeks or more apart

3) Decide intra-op based on how happy you are with your dissection on one side whether to do modified extracapsular or simply intracapsular scoop-out of other side (or leave alone as per options 1 and 2)

RE: Thyronorm not controlling hyper-T4?

Martin Atkinson — Fri, 17 Nov 2017 09:19:51 GMT

[quote user="Beats"]Either way I'd remove the thyroid.[/quote]Assuming its unilateral. It is not always possible to preserve the parathyroids even if you're an experienced surgeon and a hypocalcaemic cat is more problematic to monitor and treat than a hyperthyroid cat.

[quote user="Clive Ansell"]Or Iodine-131 therapy?, depending upon the case and the owners wishes and expectations of course.[/quote]Very much dependent, most owners don't want to/can't afford to pay or have some beef about the cat being away for 2-3 weeks and the last one I sent for I-131 therapy ended up hypothyroid, which made it hypotensive, which exacerbated existing renal disease and has to be very tightly controlled so hasn't become any easier to manage. Plus, although its irrelevant to the current thread other than to show the OP's case is relatively straightforward, it's diabetic, obese, has autoimmune skin disease and the owner struggles to pill it - joy!

In the end apart from a unilateral thyroidectomy in appropriate cases, and even then most go bilateral after 18 months, I have found methimazole bid to be the least line of resistance.

RE: Thyronorm not controlling hyper-T4?

Julie Innes — Fri, 17 Nov 2017 08:43:18 GMT

We're using it in our angry 19 year old surgery cat- seems to be working pretty well (although we haven't done bloods recently as, typical vet surgery cat we can't bleed him without sedation!) He weighs himself regularly and is definitely putting on weight (and getting a bit less angry!) We just give him it in food (I need all my fingers!!) and he takes it surprisingly well

RE: Thyronorm not controlling hyper-T4?

Stephanie Wellings — Fri, 17 Nov 2017 06:01:58 GMT

[quote user="KMurphy"]

[quote user="robloxley"]Be aware if giving it in a large meal it may not be as effective "Do not administer in food as efficacy of the product when administered via this route has not been established", though I've not come across this as a particular problem. [/quote]

I've only had clients give it in food and it's been very effective in all cases in which I've used it. One cat had some GI upset with it but other than that it's been great.

[/quote]

I called the drug company to ask about this (because I don’t think giving liquids to cats outside of food is easy at all, half of it goes up the wall) and they said that anecdotally it seems to work fine but they don’t have data for it.

In the OP‘s case I would change to another form of medication - even if you can prove the thyronorm works by admitting it and medicating yourself, that just proves where the problem is and possibly makes the owner feel a bit inadequate... but it doesn’t mean they will be any more able to medicate properly afterwards, so you need to find something that works for them at home.

RE: Thyronorm not controlling hyper-T4?

Clive Ansell — Thu, 16 Nov 2017 22:18:18 GMT

Or Iodine-131 therapy?, depending upon the case and the owners wishes and expectations of course.

RE: Thyronorm not controlling hyper-T4?

Beats — Thu, 16 Nov 2017 21:43:55 GMT

Either the drug is not working at this dose, or the owner/cat combo is not working to get the drug to where it is meant to be.

Either way I'd remove the thyroid.

RE: Thyronorm not controlling hyper-T4?

Michael Woodhouse — Thu, 16 Nov 2017 19:44:07 GMT

Board and medicate cat for a week. Re bleed and see.

RE: Thyronorm not controlling hyper-T4?

KMurphy — Thu, 16 Nov 2017 17:39:16 GMT

I've only had clients give it in food and it's been very effective in all cases in which I've used it. One cat had some GI upset with it but other than that it's been great.

RE: Thyronorm not controlling hyper-T4?

Rob Loxley — Thu, 16 Nov 2017 16:27:49 GMT

[quote user="salome2001"]So... for anyone using Thyronorm more regularly... have you had any problems with efficacy?[/quote]

Generally getting on well with it. Be aware if giving it in a large meal it may not be as effective "Do not administer in food as efficacy of the product when administered via this route has not been established", though I've not come across this as a particular problem. Why not increase the cat's dose and monitor response?
I'd have thyroid carcinoma lower down my list than compliance issues or insufficient dose, given the cat has only been diagnosed 9 months, is still on much less than 20mg/day and that the total T4 is not 'super-high'

RE: Thyronorm not controlling hyper-T4?

Clive Ansell — Thu, 16 Nov 2017 15:58:02 GMT

[quote user="Emily Rainbow"]It may be a carcinoma?[/quote]

maybe? is there a palpable and enlarging goitre or mass ?

RE: Thyronorm not controlling hyper-T4?

Emily Rainbow — Thu, 16 Nov 2017 15:40:38 GMT

It may be a carcinoma?

RE: Thyronorm not controlling hyper-T4?

Martin Atkinson — Thu, 16 Nov 2017 15:39:53 GMT

[quote user="salome2001"]I agree that compliance is usually the first item on the radar, but this lady is at home with her sole companion all day and I'm pretty sure she is getting the correct dose in the cat most days .[/quote]Never underestimate the ways in which owners can confound you into believing they are complying when they're not and I'd say second only to the administration of insulin for DM, failure to give thyroid meds to cats is top of the list. e.g. They put the medication in the food but forget to mention the cat didn't eat it.

That said, I don't like Carbimazole I've never found it as reliable or as adjustable as methimazole. Have you considered Hills YD or a transdermal gel?

RE: Thyronorm not controlling hyper-T4?

salome2001 — Thu, 16 Nov 2017 15:00:32 GMT

I agree that compliance is usually the first item on the radar, but this lady is at home with her sole companion all day and I'm pretty sure she is getting the correct dose in the cat most days . The T4 isn't just a little high, it's higher than at diagnosis

RE: Thyronorm not controlling hyper-T4?

Clive Ansell — Thu, 16 Nov 2017 14:56:58 GMT

Most cases I have seem to have stabilised well, although I can think of 2 where the dose given is fairly high.

First place I would look is owner compliance; if they say cat is getting 95%, they probably mean 50% or 5%, or even the other cat or the second cousins twice removed dog is getting it.

I have had a recent case where the owners insist that the cat gets it Vidalta every day, yet the last prescription for 30 days worth was collected in March! cat has lost weight, has HR>200 and T4 >150. Remainder of bloods and c/e all unremarkable.