Hyperthyroidism and Stage 3 Kidney disease treatment


TCS Member
Thread starter
Oct 21, 2021
Hi everyone-
I am posting for my girl shimmer who is 16 and has been treated for hyperthyroidism for about 2 years now with prescription diet. Over last few months she has lost more weighs and was now diagnosed with stage 3 kidney disease. We switched to a kidney prescription food diet but she would not eat it. After a few days with the vet she was better (we thought she was crashing) and eating. The vet has us administering sub Q at home. Last night after the 75ml she had a seizure. Are these any way connected? Is this a sign of another issue perhaps with her heart? I have a follow up with Vet but I want to ensure her final months/years are happy and pain free and not treating her for 5 different things just for me. Thanks for any feedback.


May the purr be with you
Dec 22, 2005
First, let me welcome you to the site. :welcomesign: Second, our cat was also diagnosed with Hyperthyroidism so I can definitely understand your worry and concern. He does not have kidney disease and although starting his senior years at age 11 he's younger than your girl. I'm tagging several other members who have more personal experience with H-T and kidney disease hoping they can offer their advice Antonio65 Antonio65 and FeebysOwner FeebysOwner - other members may weigh in too.

In addition, here are several threads that may have some helpful information for you:
New Hyperthyroid & likely Kidney Disease diags. :-( How to convert Phosphorous mg to Tanya's CRF chart?
Low T4 - Cause for Concern?

My educated guess regarding the seizure is that her immune system is compromised therefore contributing to the seizure but your vet is the best person to discuss this with since they know her medical history. Best of luck, please keep us updated. :alright:


TCS Member
Top Cat
Jun 13, 2018
Central FL (Born in OH)
Hi! Although heart disease can accompany both hyperthyroidism and CKD, another issue which could be your case is high blood pressure, also fairly common in cats with these conditions - and it can cause seizures. Make sure you ask the vet to check her blood pressure. Ideally, it needs to be checked multiple times within a given visit to get a more accurate reading. If it does show high, continuous follow up checks are advised.

Have you looked at this web site for all kinds of information about CKD, including data about hyperthyroidism, heart disease, and high blood pressure? I've linked to the page on hypertension (high BP), but as you look through the site you will find information about other conditions as I mentioned above. It is a lot of information to digest, but it is well worth taking some time to go through it all.
Tanya's Comprehensive Guide to Feline Chronic Kidney Disease - All About Hypertension (felinecrf.org)