Protein in urine, yet non-proteinuric


TCS Member
Top Cat
Hi there! 

My cat Boo (14 years old) has shown a 1+ for protein on every urinalysis for the past year. He has also lost weight and his appetite isn't great. When we do the protein:creatinine ratio test, it shows he is non-proteinuric. His BUN and creatinine on routine blood work have always been within range. In fact, everything was in range except this stubborn 1+ on his urinalysis. There was one time when his cholesterol was slightly elevated. We wonder if it could be some kind of early glomerular disease (although we cannot find an underlying cause). Or perhaps very early interstitial nephritis, even though there are no other red flags.

What are your thoughts on this consistent 1+ for protein on the urinalysis? I have started Boo on omega-3 fatty acids, as I have read that it can help with proteinuria. Our vet said an ACE inhibitor may be needed to help reduce the amount of protein lost through the kidneys. I'm not sure what else I can do. There is some controversy over low-protein diets for cats with proteinuria. What is your take on this?

Thanks so much, Dr. Kris.
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dr kris

TCS Member
Guest Expert

Boo is very cute!

Ok, without ever seeing Boo, im going to make a guess.

He has what I call “skinny back”. You look at him, and his back area, moving closer to his hind end / butt is the part where you can see his weight loss. He looks thinner at that location. Maybe a little, maybe alot.

Skinny Back. Am I right or wrong for Boo?

Getting back to the 1+ on the urine dipstick.

I do see alot of 1+ coming back on those dipsticks. Providing there is no infection, and a urine culture and sensitivity was done, the following will be true: The first thing to note is that those sticks have a high false positive rate for protein. They lie to me all the time! But it still is useful. Because the second thing to note is how concentrated the pee was. If Boo’s urine was concentrated (i.e. the specific gravity was high), then having 1+ protein can be a normal physiological finding. The the pee concentraion is low, with 2+ on the stick, yes, im looking for underlying causes. If the urine protein / creatinine ratio is normal - and I have several normals, I become very happy and confident that I have no PLN (protein losing nephropathy).

Which brings us to skinny back.

Take 100 cats at Boo’s age, and 30 of them start to get it. The reasons for this weight loss can be complex, often independent of what the kidneys are doing. When you look at the data for elderly people, we see the same phenomenon.

Zack, my own cat is doing this as well. Describing the in’s and outs of preventing this weight loss is something I have in the works (either as an upcoming blog post of video).

For Boo, I would consider the following when talking to your vet:

1) Fish oils - yes! Regardless or proteinuria or not.
2) Ace inhibitors - Im probably not going to use that yet. Your fish oils may be doing this job for you. Plus, I dont want anything to mess with his appetite right now because:

3) Cats at 14 will probably have increased MER. This is fancy talk for saying they need more calories because they become less efficient at digesting their food, their requirements for healthy proteins and fats actually increase. This implies, for a non-proteinuric cat, that you are actually increasing their dietary protein, and not decreasing it.

All these things are what we are doing with Zack and his somewhat skinny back.

Hoped that helped!

Dr. Kris


TCS Member
Top Cat
View media item 229618
Aw, thanks! Yes, he has muscle wasting. His spine and hips are quite boney. Most of the photos in his TCS album are older and so it has gotten worse. The photo on the right is semi-recent (taken two months ago). And yes, C&S was done, never any infection or bacteria or crystals. His specific gravity has always been fine, as well. There was one urinalysis where the urine came back "cloudy" instead of "clear", but that only happened one time last year. The most recent one was clear. He's due for another urinalysis soon.

Thanks for much for your reply!