Tachypnoeic hyperthyroid, with ALT 1100

Re: Tachypnoeic hyperthyroid, with ALT 1100

Bob Russell — Mon, 28 Apr 2014 15:10:36 GMT

Have to admit I have not seen any real difference in side effects between the two drugs. Felimazole is a bit more flexible dose wise.

I have one that went on neo-mercazole (bad boy!) and when that became unavailable switched to the generic. It has not looked back! Doing much better than it ever did on anything else!

I do wonder how bioavailability varies between products and individuals!

Re: Tachypnoeic hyperthyroid, with ALT 1100

sandpiper — Mon, 28 Apr 2014 11:39:04 GMT

[quote user="John Flynn"]Anecdotally, I switched back from vidalta to felimazole a few years ago as I felt that cats just didn't do as well and seemed to have more problems [/quote]

Re: Tachypnoeic hyperthyroid, with ALT 1100

John Flynn — Fri, 25 Apr 2014 20:14:19 GMT

[quote user="David Mills"]

Degree of ALT elevation means very very little in cats (or dogs for that matter), I consider it essentially a binary test.

[/quote]

I think the reduction of a continuous variable like this into a binary test is generally unhelpful, in the absence of a pre-disease comparison, then assessment of magnitude of elevation w.r.t the upper reference limit (URL) seems generally most appropriate. Why introduce an arbitrary cut-off point? Degree of elevation above what is irrelevant?

I agree that the number "1100" means very little in of itself, but if we assume that this was tested on a properly calibrated test in which 97.5% of healthy dogs demonstrated an ALT level below, say, 100 U/L, then at an elevation of >10 x URL in a cat, I'd be happy to say that this was likely indicative of significant clinica hepatopathy. Waiting for liver function to deteriorate to a measurable amount seems rather unecessary... Had the ALT been increased at 110, say, I'd consider this less of an issue.

Some thoughts from those more learned than myself:

"The magnitude of increased enzyme activity may limit the possible explanations. For example, an ALT activity of 15 x URL is probably caused by hepatocyte damage, not severe muscle damage."

"For the cytoplasmic enzymes... the magnitude of increase may relate to the severity of damage; that is, slight damage may cause values <2 x URL, whereas severe damage might cause values ?50 x URL. However, magnitude of increase does not differentiate reversible damage from irreversible damage, or local damage from diffuse damage."

ref: Fundamentals of Veterinary Clinical Pathology, 2nd ed (2008) eds Stockham&Scott

Re: Tachypnoeic hyperthyroid, with ALT 1100

David Mills — Fri, 25 Apr 2014 19:22:15 GMT

This cat isn't in heart failure with that LA/Ao measurement and these X-rays. Generally dyspnoea can only be CHF if there is LA>16.5mm in cats. Did you mean thickened atrium or ventricles? The former is almost unheard of.

Degree of ALT elevation means very very little in cats (or dogs for that matter), I consider it essentially a binary test.

I woud also highly recommend unilateral thyroidectomy - in half an hour you can solve the cat's primary problem for around a year and a half, and in about 40% it will solve the problem completely. Hypert4 kills far more quickly than CRF so it almost all cases I'd crack on with this.

Never noticed a difference between vidalta and felimazole - AFAIK the side effects are linked almost entirely to methimazole, which carbimazole is broken down into so if you have side effects with one you will almost certainly get them in the other. Anecdote, of course.

Re: Tachypnoeic hyperthyroid, with ALT 1100

Martin Atkinson — Fri, 25 Apr 2014 19:07:16 GMT

[quote user="John Flynn"]Anecdotally, I switched back from vidalta to felimazole a few years ago as I felt that cats just didn't do as well and seemed to have more problems - would be interested to hear if this is the same experience as others or if their is any decent objective data on the relative incidence of adverse reactions and their severity between the two drugs?[/quote] Anecdotally I would agree. When previously the only choice for medical treatment was human carbimazole, Felimazole was a breath of fresh air in terms of reduced side effects and ability to control the TT4. I cannot see the point in going back to the future unless the single daily dose is critical (you can often get away with a single dose of felimazole anyway)*. Being forever cynical my view was that Vidalta was just a back door through the casade with an old-fashioned drug that had been superceded.

But back to the OP, cardiac X-rays can't tell you if the cat has HCM as it may be reduced internal chamber size due to HCM. If echo is not an option then try my favourite NT-proBNP. I have found it a very accurate predictor of cardiac disease in cats in most cases. And I agree that the raised ALT may be due to the poorly controlled hyperthyroidism and carbimazole.

* PS don't tell anyone I told you but you can also crush felimazole and put it in the cat's food without loss of bio-availability if there is a compliance problem, just address the potential public health issues with the client!!

Re: Tachypnoeic hyperthyroid, with ALT 1100

Laura Marshall — Fri, 25 Apr 2014 14:41:57 GMT

Thanks for the responses. I am assumining that uncontrolled hyperthyroidism is responsible for some of what I'm seeing, but wanted other peoples thoughts to see if similar! I hadn't even thought about the meds themselves causing the marked elevation in ALT. I think this adds fuel to the argument to switch to felimazole. The responses to the X-rays are very useful as ewell, I wasn't seeing significant changes to justify any meds at this stage. I think I'll get better controlled over the t4 and see what we're left with! Does anyone have any conversion rules that they use when going from vidalta to felimazole?

Re: Tachypnoeic hyperthyroid, with ALT 1100

vanessab — Thu, 24 Apr 2014 19:02:02 GMT

comment regarding ALT and previous liver evaluation: ALT is more liver specific in cats and elevations are considered significant, unless other causes can be identified (e.g HT4, drugs etc.) BAST may be useful to evaluate liver function but will be normal in early disease and liver biopsy may be the only way to successfully r/o primary hepatic disease. The liver appears to extend beyond the costal arch in the XR? 1100 is a large increase, is there any possibility of lab error?

regarding the heart, remodelling changes due to HT4 are usually less severe than primary cardiac dz so would depend on the measurements. Cardiac biomarkers may be useful if you want a definite diagnosis?

Re: Tachypnoeic hyperthyroid, with ALT 1100

John Flynn — Thu, 24 Apr 2014 03:39:14 GMT

[quote user="Francisco Gomez"]Any other opinions anyone?[/quote]

An opinion from another non-expert, but I vote for lower airway disease as cause for any (expiratory) dyspnoea.

Cardiovascular structures appear within normal limits to me on the (rotated) lateral and DV radiographs.

I'd blame a combination of the uncontrolled hyperT4 and the vidalta for the elevated ALT. From its datasheet:

"The treatment may induce increase of liver enzymes. Severe cases may require temporary or permanent treatment discontinuation. However, these elevations are usually reversible following drug discontinuation, although symptomatic therapy (nutritional and fluid support) may be required."

Indeed, the vidalta could be blamed for almost anything

"Most frequent common adverse reactions encompass vomiting, diarrhoea, reduced appetite, loss of condition, lethargy, tachycardia, polydipsia, dehydration, and polyuria. Dermatological signs (pruritus, moist dermatitis, erythema, alopecia) have also been reported. These clinical signs are usually mild, adequately controlled by symptomatic therapy and do not require treatment discontinuation. However, if more severe clinical signs occur that do not respond to symptomatic therapy, the dose should be reduced or treatment stopped according to risk:benefit evaluation. In cases of serious adverse reactions, mortality, possibly due to the product, might occur if treatment is not discontinued. In some cases, signs of gastrointestinal bleeding such as bloody vomit, oral haemorrhage or dark feces can be observed. These signs should be considered as serious and require immediate action (dose reduction or treatment discontinuation). Weight loss, dyspnoea, aggressiveness, disorientation, ataxia or pyrexia have also been reported in rare cases. Treatment of hyperthyroidism may result in a reduction in the glomerular filtration rate. In severe cases, where azotaemia develops, temporary or permanent treatment discontinuation may be required. The treatment may induce increase of liver enzymes. Severe cases may require temporary or permanent treatment discontinuation. However, these elevations are usually reversible following drug discontinuation, although symptomatic therapy (nutritional and fluid support) may be required. Anaemia, increase or decrease in white blood cell count, neutrophilia, thrombocytopaenia, eosinophilia and/or lymphopaenia may also occur, in particular during the first 4-6 weeks of treatment. Treatment discontinuation may be required in case of persistent and marked disorder. In most of the cases, the abnormality will resolve spontaneously within 1 month after treatment discontinuation. Positive antinuclear antibody titres have also been reported. It appears that adverse reactions are reversible on cessation of treatment."

Anecdotally, I switched back from vidalta to felimazole a few years ago as I felt that cats just didn't do as well and seemed to have more problems - would be interested to hear if this is the same experience as others or if their is any decent objective data on the relative incidence of adverse reactions and their severity between the two drugs?

Further anecdotally, and trying to be practically helpful, I find that these cats do better on the whole with at least a unilateral thyroidectomy. Switching to Hill's y/d may be an alternative option, but I have extremely limited experience of its use personally.

Re: Tachypnoeic hyperthyroid, with ALT 1100

Laura Marshall — Wed, 23 Apr 2014 23:04:48 GMT

No other clinical signs. Electrolytes were normal. Don't have the biochem results in front of me for numbers, but there were elevations in BUN, ALT, ALKP and cholesterol.

I'm aware that the hyperthyroidism is not under control, and this is being addressed currently. But clearly this is not the only issue with this cat.

Re: Tachypnoeic hyperthyroid, with ALT 1100

Francisco Gomez — Wed, 23 Apr 2014 14:42:34 GMT

Any other signs? I.e. Temperature, neuro, gi, etc? Is the rest of biochem normal? And electrolytes? Even if it was cardiac, I'd assume it would be secondary to hyperT4. 84mmol/l isn't under control. Quick glance at x-ray, i don't see CVC too enlarged in the lateral view and lung fields look pretty sound too. Any other opinions anyone?