Janet
Thank you.
You MUST get her on a binder right away. You really need to get that phosphorus level down ASAP. And yes, you were correct in your PM that her P x Ca exceed 70...but just barely.
I would get Dr. Lisa's Phosphorus Charts we linked the other day and I would get the lowest ones you can find that do not have any of the products she is allergic to. Then find the ones low in carbs. You want to shoot for less than 200 mg P per 100 calories or less than 1% P on a dry matter basis. If you can't find any lower that she can have, get as close as you can. But if you get your vet to prescribe an aluminum hydroxide binder, that is best of all. Phosphorus control is KEY to them staying stable with CKD and you don't want to play catch up.
You can get aluminum hydroxide cheapest at thrivingpets.com. You just sprinkle it on the food, mix, let it sit a minute, and then give it to her. It binds the P in the food so don't give it directly to Izzy. I would read and reread
The Importance of Phosphorus Control on Tanya's website. GREAT STUFF! Alot of vets miss this because the lab ranges show normal up to 8 or so; but that includes kittens and kittens always have higher P levels as they are making bone. As you have on one of the SSs, you should be shooting for 4. Gussie is starting his fourth year of CKD and his P is 4.4.
I also think you need to be doing subq fluids daily. It's better to do a small amount daily then to do a larger amount EOD.
If you don't have her on a methycobalamine supplement (Zobaline is good for FDs) PLUS a multi B like Jarrows B Right, you also should do that now. CKD cats pee alot of the vitamin B out and the methyl B12 and multi B help control anemia which is another really important factor. You want to keep the HCT up as long as you can; once it falls below 20%, they need erythropoetin stimulating agents and those come with their own issues. She will feel better longer if her P and anemia are under control. And if she gets fluids every day.
Have you had her blood pressure checked lately? They need to keep an eye on that. It is very common for CKD cats to have high BP. Gus has been on amlodipine (a low dose) for two years now....no side effects.
Let me know if you have questions and how I can help.