Early kidney disease and hyperthyroidism in elderly cat

[4horses]

My 15 year old cat has been diagnosed with hyperthyroidism. All other bloodwork was normal. Urine was slightly dilute. We treated the hyperthyroidism for 2 months and repeated bloodwork. The new bloodwork was all normal, except thyroid values were too low. Vet suggested reducing his thyroid medication.

SDMA test was 16, which is one point above normal.

During this time, kitty has been drinking more than normal and having increased urination and dilute urine. His coat still looks terrible. He’s shedding like crazy. Now I know coat problems are typical with thyroid problems, but i had hoped the medication would improve things. He seems more lethargic then normal as well.

If he has kidney disease why would BUN and creatinine be normal? The vet did say it wasn’t diabetes. The vet suggested it was possibly a urinary tract infection, but he hasn’t had bloody urine and the last urinalysis was normal except for dilute urine. Since hyperthyroidism and kidney disease usually occur together, it could be the early stages of chronic kidney disease.

My regular vet wasn’t in last week to go over the results. I plan on calling them back next week to see what we do next.

Should I put him on a kidney disease diet and see if it helps? His weight isn’t bad right now, but he has lost muscle that he needs to regain. He’s like an old horse with muscle loss over the topline. His spine is rather prominent, but he has a belly on him.

I have no experience with kidney disease in cats. Not sure what to expect from here. If you have a cat with kidney disease please tell me how you manage it. The food he is on is high in phosphorus, not sure if a lower phosphorus diet would be more helpful?

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[4horses]

Anyone?

[OzarksRider]

Hyperthyroidism doesn’t cause kidney disease, but treating the hyperthyroidism can unmask already existing disease. BUN and creatinine will remain normal until the kidneys have lost most of their function, so if these values are normal your cat likely still has pretty good kidney function. Did they test the urine for protein? If the vet did a dipstick urinalysis on your cat and everything was normal then it’s unlikely that he/she has a urinary tract infection. And if there was no protein in the urine the cat probably doesn’t have kidney disease. The increased drinking and peeing are two symptoms that can be caused by hyperthyroidism, and lethargy can also be caused by thyroid, so it’s important to have a thorough workup to know exactly what you’re dealing with. The American Association of Feline Practitioners has published treatment guidelines for feline hyperthyroidism; you can access the article here: https://journals.sagepub.com/doi/10.1177/1098612X16643252 (If the link doesn’t work just Google 2016 Guidelines for the Management of Feline Hyperthyroidism.)

I’ve had two hyperthyroid cats, and both were treated with radioactive iodine. One cat was first treated with methimazole tablets, but she couldn’t tolerate them. I took her to a clinic for radioactive iodine treatment and it worked like a charm. She recovered completely and lived happily for two more years. She was euthanized because of inoperable squamous cell carcinoma in her jaw; nothing to do with hyperthyroidism or radioactive iodine. The second cat was also treated with radioactive iodine, and his hyperthyroidism was also completely cured. Unfortunately, he died a few months later from cardiomyopathy which was likely present before the hyperthyroidism. Both of these cats were in their teens (13 and 14) when they were diagnosed.

For my money, radioactive iodine is the way to go with hyperthyroidism because it completely cures the disease. It’s expensive up front, but over time it’s cheaper than medication if the cat lives long enough. That’s because you have to buy the medication and then pay for periodic vet visits and lab tests to monitor the dose. And it completely eliminates the stress for both you and the cat of trying to administer medication twice a day, every day.

I hope your cat does well; I’ve been there and I know how hard it can be to know what’s the right thing to do. Please post an update when you find out more.

[rubygirl1968]

I have no experience with hyper t but my old cat, Thomas had ckd (chronic kidney disease).

He wouldn’t eat the rx diets but managed quite well with daily fluids for 3 years after diagnosis. I wish I’d done the fluids sooner.

I wish you all the best with your kitty.

[Larbear]

I had a hyperthyroid cat with borderline kidney disease. It was my understanding that the hyperthyroid can worsen the kidney disease (even on the methimazole.

I did transdermal methimazole for awhile to see how his kidneys were and when he showed that the kidneys were stable, I took him in to do radioactive iodine. Turned out he wasn’t a candidate because during the initial tests they thought he had lymphoma (aggressive large cell) and that by the time he had recovered, the cancer would take him. He did have IBD and I believe around the time he came off the MMI, his IBD symptoms were pretty severe. Once back on his MMI and him finally eating food that I had been trying for ages to get him to eat, his IBD calmed down and he thrived for almost a year before his kidneys went. I do feel if he had been able to do the radioactive iodine his kidneys would have held out longer (speculation on my part of course).

I would say look into a phosphorous binder but I would be careful about restricting protein, they will muscle waste if they don’t get enough. I would try to feed something that has good quality protein. I don’t know if there’s any real evidence that restricting the protein slows the progression of the disease.

[Rain]

@Larbear

I would say look into a phosphorous binder but I would be careful about restricting protein, they will muscle waste if they don’t get enough. I would try to feed something that has good quality protein. I don’t know if there’s any real evidence that restricting the protein slows the progression of the disease.

100% agree with this. My “kidney cat” lived another 6 years on a phosphorous binder – she would not eat a kidney diet. Phos-bind is not too expensive and I think you can get it on Amazon. Also agree with not restricting protein.

Since hyperthyroidism “speeds things up” your cat may seem lethargic just because the meds are working and slowing things down, so to speak.

[Larbear]

If your kitty is becoming lethargic, I wonder if the MMI is causing GI upset? Is he getting MMI orally? If so maybe try the transdermal form. My old kitty man did much better on that than the pill form.

[4horses]

I’m not a huge fan of restricting protein because he has lost so much muscle already. I will look into the phosphorus binders.

The vet wants to wait before doing further bloodwork. He wants to see how he does on the lower dose of felimazole.

[shiloh]

Poor kitty. I’m so sorry you both are having to go thru this. BTDT and I have to say that I felt like the little Dutch boy at the dike trying to stop the ocean. When one hole got plugged up, another would pop open. Thyroid meds did not work for my cats (I don’t think we got the right balance but then we never had enough time either). If you need help/support with giving fluids, I can help and have some supplies I can let you have. I have needles and may have some line as well. All fresh still in unopened packages. Let me know.