Hyperthyroidism & elevated SDMA

[ajp]

Hi Everyone,

So recently my 12 year old cat George had been losing weight, eating more and vocalising a lot. I took him to the vet to do a blood test, and it turns out that he has hyperthyroidism(t4 level of 195) and elevated SDMA(22) which is apparently an early indicator of CKD. His creatanine levels were within normal parameters.

So my vet told me, based on the elevated SDMA levels, that she suspects he is in an advanced state of renal failure, as the hyperthyroidism is likely masking the underlying kidney issues. George was put on methimazole topical treatment and a renal care diet.

This news obviously devastated me.

I guess I was just wondering if anyone had experienced similar issues with feline hyperthyroidism? did CKD present itself after the treatment?

[Mollycat]

Sorry for your bad news, one of these is hard to take let alone both at once.

Unfortunately hyperthyroidism masking kidney failure is one of the big issues about it. Although your George is right on the age bracket for HT he is a little young for advance kidney failure, which isn't a very encouraging sign, but that doesn't mean both issues can't be successfully managed.

My girl Molly was hyperthyroid and because of the way she is our only option was the curative but expensive and drastic radioactive iodine. Before this treatment can be done the cats go through 2 days of testing including x-rays, scans, blood tests, blood pressure, more heart tests, and more, just to evaluate if they are suitable for the treatment. In the 5 months while we were waiting for the treatment, her hyperthyroidism was controlled by diet, it's a pate type canned food and kibble currently only made by Hills that must be stuck to absolutely to work at all. It works be reducing iodine so low that the thyroid gland can't make any more thyroid hormone than the bare minimum. Awesome for cats that can't take medicine.

What happens is that the thyroid has a small tumour which in almost all cases is non-cancerous but which makes the cat produce sky-high levels of thyroid hormones. These raise metabolism, hence the constant hunger and weight loss, but they also produce other changes including high blood pressure. The high blood pressure is dangerous for the heart as it is pumping so much harder the heart walls thicken and it eventually fails, and it can also damage the eyes and eventually cause blindness. So it's not a disease that can be left untreated. But the high blood pressure also makes the kidneys work artificially better, and that's what your vet means by masking the renal failure.

So as the thyroid failure is brought under control, blood pressure drops (saving the heart and eyes) and the extent of the kidney failure begins to show. Kidney failure on its own is a degenerative condition with no cure, but can be very successfully managed for a long time. My first CKD cat was 8 when she was diagnosed and lived a full and happy 8 years more with just a change of diet, no drugs and no extra fluids. Sure enough my Molly who had some very early damage to her eyes and heart showed up some low level kidney issues after treatment, but she is not even on a renal diet at the moment, mostly because I need her on high protein to try and rebuild her muscle loss and then we will monitor her kidney levels.

SDMA is a relatively new diagnostic tool for identifying kidney disease and cannot be taken alone as a reliable diagnosis, and anyway George's other issues are probably more urgent as HT needs to be under control before renal function can be properly evaluated. This article describes SDMA in CKD very well https://todaysveterinarypractice.com/ea ... larginine/ Also, it's primarily about kidneys but there is an important section on kidneys with hyperthyroidism, http://www.felinecrf.org/index.htm which we recommend to everyone with a new renal insufficiency diagnosis - it's just brilliant and one of the most helpful resources on the www.

There is a lot to take in but with a good vet, Tanya's Pages and Cat Chat, you're already well on the road to the best care possible for George and for yourself.

[booktigger]

I'm sorry to hear this, I know my vet doesn't like to get thyroid levels too under control when there are kidney issues, as the high blood pressure helps the kidneys. I disagree with SDMA not being reliable, it has been used for a few years now and as George's tests showed, picks it up before the creatnine levels are affected, so can be managed at an earlier stage

[ajp]

Sorry for your bad news, one of these is hard to take let alone both at once.

Unfortunately hyperthyroidism masking kidney failure is one of the big issues about it. Although your George is right on the age bracket for HT he is a little young for advance kidney failure, which isn't a very encouraging sign, but that doesn't mean both issues can't be successfully managed.

My girl Molly was hyperthyroid and because of the way she is our only option was the curative but expensive and drastic radioactive iodine. Before this treatment can be done the cats go through 2 days of testing including x-rays, scans, blood tests, blood pressure, more heart tests, and more, just to evaluate if they are suitable for the treatment. In the 5 months while we were waiting for the treatment, her hyperthyroidism was controlled by diet, it's a pate type canned food and kibble currently only made by Hills that must be stuck to absolutely to work at all. It works be reducing iodine so low that the thyroid gland can't make any more thyroid hormone than the bare minimum. Awesome for cats that can't take medicine.

What happens is that the thyroid has a small tumour which in almost all cases is non-cancerous but which makes the cat produce sky-high levels of thyroid hormones. These raise metabolism, hence the constant hunger and weight loss, but they also produce other changes including high blood pressure. The high blood pressure is dangerous for the heart as it is pumping so much harder the heart walls thicken and it eventually fails, and it can also damage the eyes and eventually cause blindness. So it's not a disease that can be left untreated. But the high blood pressure also makes the kidneys work artificially better, and that's what your vet means by masking the renal failure.

So as the thyroid failure is brought under control, blood pressure drops (saving the heart and eyes) and the extent of the kidney failure begins to show. Kidney failure on its own is a degenerative condition with no cure, but can be very successfully managed for a long time. My first CKD cat was 8 when she was diagnosed and lived a full and happy 8 years more with just a change of diet, no drugs and no extra fluids. Sure enough my Molly who had some very early damage to her eyes and heart showed up some low level kidney issues after treatment, but she is not even on a renal diet at the moment, mostly because I need her on high protein to try and rebuild her muscle loss and then we will monitor her kidney levels.

SDMA is a relatively new diagnostic tool for identifying kidney disease and cannot be taken alone as a reliable diagnosis, and anyway George's other issues are probably more urgent as HT needs to be under control before renal function can be properly evaluated. This article describes SDMA in CKD very well https://todaysveterinarypractice.com/ea ... larginine/ Also, it's primarily about kidneys but there is an important section on kidneys with hyperthyroidism, http://www.felinecrf.org/index.htm which we recommend to everyone with a new renal insufficiency diagnosis - it's just brilliant and one of the most helpful resources on the www.

There is a lot to take in but with a good vet, Tanya's Pages and Cat Chat, you're already well on the road to the best care possible for George and for yourself.

Thanks so much for the detailed reply.

My vet did speak to me about the radiation therapy, though wants to monitor how he responds to the topical treatment first. Everything i've read about this treatment suggests this is the "gold standard" way to treat an overactive thyroid, so I am hoping George will be eligible for this. I hadn't heard of diet as a treatment, but this is interesting to know. He has had a bit of diarrhoea today, but hopefully that is due to the change in diet(royal canin renal prescription food).George seems to be responding well to the methimazole, he was noticeably calmer last night after his first treatment in the morning which is encouraging.

It is encouraging to hear that your CKD cat managed to live that many years after diagnosis. I'm hoping George's kidneys are in a manageable state such that he can last at least another year(hopefully more), I'm not ready to let him go just yet!

Thanks for the resources, ill be sure to use them all so I can be as well informed as possible. Hope your Molly is doing well!

[Mollycat]

I'm sorry to hear this, I know my vet doesn't like to get thyroid levels too under control when there are kidney issues, as the high blood pressure helps the kidneys. I disagree with SDMA not being reliable, it has been used for a few years now and as George's tests showed, picks it up before the creatnine levels are affected, so can be managed at an earlier stage

My apologies, I must have read an old article - it did say it would allow for much earlier detection but at the time it wasn't as reliable but the indication was anything over 14 indicated further tests. Thank you for the correction and update

[ajp]

I'm sorry to hear this, I know my vet doesn't like to get thyroid levels too under control when there are kidney issues, as the high blood pressure helps the kidneys. I disagree with SDMA not being reliable, it has been used for a few years now and as George's tests showed, picks it up before the creatnine levels are affected, so can be managed at an earlier stage

That's interesting, I guess that is why the radiation treatment was not recommended up front in my cats case as a gradual lowering of thyroid levels allows for a more malleable approach to treatment when the kidneys are a concern.

Apparently SDMA does flag earlier than creatinine levels, as creatinine can be lowered by the loss of muscle mass.

[ajp]

This was George yesterday, 4.67 kg. He used to be around 7kg.

[booktigger]

When I got Lucy 5 years ago, my vet offered me the chance to be included in testing but then when I turned up at the vets bleeding from getting Lucy in the carrier we changed our mind, but 12 months later, her CKD was picked up by the SDMA, she didn't really have symptoms, she'd just been sick once or twice and occasionally drank a bit more water. Which means that we got her diagnosis 4 years next month, she is starting to drink more now, and refusing renal wet food, but in the climate, not easy to take her for bloods, the staff would lose some blood if I couldn't be there too