Low urine specific gravity but normal blood work?

[drelocks]

Our cat (8) has chronic pancreatitis and is on daily prednisolone since 2020.. Since 2021 he's had low urine specific urine gravity bounces between 1.010 and 1.017. these tests are sporadic and usually done in ED during a flare.

Our vet just performed yesterday outside of flare and it's still low. All of CBC completely normal, blood salt level normal, glucose normal. Creatinine is 1.4.

She said she's not too concerned but we will check again in couple months. Can either be early warning of kidney disease, pred use, or diabetes insipidus?

He does love drinking out of his water fountains and does pee biggish clumps 5 times a day, but this has been his normal for years and nothing has changed. He's never dehydrated.

Anyways in the meantime vet said not to worry. Plan is to start a taper on his pred, retest, keep all his fountains handy but stop adding extra water to his wet food. He only eats wet food.

Anyone with experience with my super long story? Thanks in advance!

 

[silent meowlook]

Your story wasn’t long at all.

I am not a vet.

With chronic kidney disease, thee has to be around a 70% loss of kidney function ( so basically only 1/2 of a kidney working) for i to show up on bloodwork.
I would, for now, follow your vet’s advice and recheck after the Prednisolone has been decreased.

Another thing you could do, would be an abdominal ultrasound to see what the kidneys look like. If you do want to do that, it is important that you have it done by a board certified internal medicine vet, as ultrasounds are subjective and you need a vet with extra training, knowledge and experience.

 

[drelocks]

Your story wasn’t long at all.

I am not a vet.

With chronic kidney disease, thee has to be around a 70% loss of kidney function ( so basically only 1/2 of a kidney working) for i to show up on bloodwork.
I would, for now, follow your vet’s advice and recheck after the Prednisolone has been decreased.

Another thing you could do, would be an abdominal ultrasound to see what the kidneys look like. If you do want to do that, it is important that you have it done by a board certified internal medicine vet, as ultrasounds are subjective and you need a vet with extra training, knowledge and experience.

His ultrasound in January was normal outside of pancreas! Thanks!

 

[FeebysOwner]

Hi. From what I have read a lower USG can be a warning about kidney disease, pred use, and/or diabetes insipidus. I would want to do one change at a time - starting with lowering the Pred over time with re-testing along the way. Although you have had a fair amount of testing done that can help identify diabetes insipidus, there are a few others as well. See the list of tests in the article linked below. I also included an IRIS article about USG.

I am not sure what is the value of reducing his water intake. If nothing else comes of other testing, he may simply have a lower USG due to the volume of moisture he is getting. I have not read anything to suggest that raising the USG by lowering moisture intake has a positive purpose. I would ask the vet what is to be gained by lowering the amount of moisture he takes in.
Diabetes Insipidus in Cats | PetMD
IRIS Kidney - Education - Using Urine Specific Gravity (iris-kidney.com)

 

[emocatowner]

If I remember correctly, my vet said something about how proper USG tests should be done when the cat hasn't had any water for a number of hours, to see how much the kidneys are actually capable of concentrating urine, otherwise it can just be low because the cat likes drinking water. I also remember him saying it's not really worth doing that test when you have bloodwork.

Steroids like pred will also decrease the USG, so her idea of lowering it and rechecking also makes perfect sense.

It's probably ok to not add extra water to his wet food, it sounds like he's doing just fine on hydration on his own. And it may help get more calories in him, if there's any weight struggles due to the pancreatitis.

 

[FeebysOwner]

It's probably ok to not add extra water to his wet food, it sounds like he's doing just fine on hydration on his own. And it may help get more calories in him, if there's any weight struggles due to the pancreatitis.

Hydration - and perhaps, fluid support - is/are generally considered crucial in the treatment of pancreatitis.

 

[emocatowner]

Hydration - and perhaps, fluid support - is/are generally considered crucial in the treatment of pancreatitis.

During a flare-up, if there is dehydration, doing subcutaneous fluids would be more effective. Also, that way he can eat more food before filling up his belly, as they often struggle with eating, and the only alternatives I can think of to that, are syringe feeding and feeding tube. Though I doubt a little bit of extra water in his food will really make a difference either way, when we have such a well hydrated and cared for kitty.

 

[FeebysOwner]

During a flare-up, if there is dehydration, doing subcutaneous fluids would be more effective.

That is what I meant by fluid support.

Though I doubt a little bit of extra water in his food will really make a difference either way,

Hence, one of the reasons not to reduce the water he is used to getting in his food. Reducing it isn't going to make much of a difference, other than to change the routine he is used to, without a real purpose for doing so.