Stage 1 kidney disease in cats: what it means and how long cats live

What does stage 1 kidney disease mean?

If you're reading this, your cat probably looks completely fine, and somebody has just told you her kidneys aren't. That's a strange place to be, and it's worth slowing down here, because stage 1 is the best news this diagnosis comes with.

Stage 1 is the earliest of the four IRIS stages, the system vets use to describe how far kidney disease has gone. It means there's evidence of kidney damage, but the blood values that set the stage are still inside the normal band. She isn't sick from her kidneys yet. Most cats at this stage are only found because somebody looked: a senior screening panel, a urine test run for some other reason, or an SDMA that came back higher than expected.

Most cats aren't found here. They're found at stage 2 or later, often on a routine senior panel or after the water bowl has been emptying faster for a while. A cat caught at stage 1 has more room ahead of her than a cat caught at any later stage, and that's the frame I'd want you to keep.

The numbers behind stage 1

The stage comes off two blood values read together. Creatinine is a waste product healthy kidneys clear. SDMA is a newer marker that often rises earlier and is less thrown off by how much muscle she has.

So if her blood looks normal, what put her in stage 1? Usually one of three findings. An SDMA that's above the lab's line. Urine that's getting dilute, because the ability to concentrate urine often slips before any blood value moves. A healthy cat runs a urine specific gravity above about 1.035, and a kidney cat drifts down toward 1.008 to 1.012, which isn't far off tap water. Or protein leaking into her urine. The urinalysis page covers both urine tests properly.

One rule that matters a lot at this end of the scale: staging is supposed to be done on a well-hydrated, stable cat and confirmed on more than one check. A single SDMA a little over the line, drawn on a hot day from a cat who'd been off her water, is a reason to recheck rather than a diagnosis on its own. And if the two markers disagree on separate checks, IRIS says to go by the higher one, because creatinine leans on muscle and a thin older cat's creatinine can flatter her.

Substaging: protein and pressure

IRIS asks for two more things alongside the stage, and they matter at stage 1 as much as anywhere, because both are treatable and neither shows up on a routine blood panel.

Urine protein, as a UPC (urine protein to creatinine ratio). Under 0.2 is non-proteinuric, 0.2 to 0.4 is borderline, above 0.4 is proteinuric. A stage 1 cat who's leaking protein is a different conversation from one who isn't.

Blood pressure. Under 140 is normal, 140 to 159 prehypertensive, 160 to 179 hypertensive, 180 and above severe. High blood pressure can be both a cause and a consequence of kidney damage. If your vet has the equipment, it's worth doing. Plenty of clinics don't, mine included, and the blood pressure page covers what to watch for instead.

How long do cats live with stage 1 kidney disease?

There isn't a published median for stage 1, and I'd rather tell you that plainly than borrow a number from a later stage. Cats are rarely found this early, and the ones who are tend to be followed for other reasons, so the survival studies don't have a stage 1 group worth quoting.

The honest expectation is years, often many of them. The life expectancy page has the published figures for stages 2 to 4, and they're worth knowing as the shape of the road ahead. But the stage 2 figure, about three years, was measured in cats diagnosed in the upper half of stage 2, which is further along than a cat in stage 1.

What moves her course from here is mostly the same short list that matters at every stage: whether she's losing protein in her urine, whether her blood pressure is high, whether her phosphorus stays on target, and whether anything treatable is sitting behind the damage.

What treatment looks like at stage 1

Mostly, it looks like watching, and that's on purpose. The temptation to throw everything at a cat who feels perfectly well is real, and there's no need.

Look for a cause you can do something about. In most cats nobody ever finds a single cause, and age does most of the work. But a few contributors are worth ruling in or out while she's well, because they're treatable: a kidney infection with no outward signs, high blood pressure, and anything she's been given that's hard on kidneys, especially an anti-inflammatory meant for a person. The causes page walks through the list.

Get a UPC if she's never had one. It's cheap, any practice can run it, and it's the one result most likely to change what she's prescribed.

Talk about food, without a fight. The lower-phosphorus diet is the most evidence-backed thing you can do at home for a kidney cat, and the kidney diets page covers the gentler early-stage formulations. Whether she needs one yet at stage 1 depends on her phosphorus and her urine, so it's a question for your vet with her numbers in front of them, not a rule.

Recheck on a schedule. Every three to six months is the usual range at stage 1, blood and urine together. Write each result down with the date. One number is a dot. Four make a line, and the line is what tells you how she's really doing. The recheck page covers what a complete recheck includes.

Keep her kidneys out of harm's way. No human painkillers, ever. Make sure every vet who sees her knows about the kidneys before anything is prescribed. And keep lilies out of the house entirely, because they're catastrophic in cats.

One more, because it comes up at this stage more than any other. If she needs dental work, ask your vet about it now rather than later.

Once a cat is stage 2 or beyond, I don't do dental cleanings under anesthesia in my own practice, though some clinics do careful dental work in kidney cats. The nausea and vomiting page covers both, and stage 1 is a different conversation.

What to ask your vet at stage 1

Take this list in, or send it ahead:

• Which finding put her in stage 1: her SDMA, her urine concentration, her urine protein, or something else?
• Was she well hydrated when the sample was drawn, and should we confirm it on a second check?
• What was her UPC? If it hasn't been done, can we add it?
• Is her blood pressure something you can measure, and if not, what should I watch for at home?
• Where is her phosphorus against the stage 1 target of under 4.5?
• Is there anything treatable we should look for, like a kidney infection?
• When do you want to see her again, and what will you test then?

The view from stage 1

She doesn't know anything's changed, and for now very little has. She'll keep doing what she does, and the most useful thing you can do is the boring part: write the numbers down, weigh her on Sundays, and keep the rechecks.

If her next results move her into stage 2, that's the most common place cats are diagnosed and there's still a lot of time there. The stage 2 page covers what changes. The IRIS stages page has the full chart for all four stages if you want to see the whole map.