Cat Creatinine Levels Chart: Normal Range & What Values Mean
Last reviewed: April 2026
Cat Creatinine Key Levels
Normal creatinine: 0.8-2.4 mg/dL. Values above 2.4 with symptoms indicate kidney disease requiring investigation.
Worried about your cat's kidney values?
See creatinine, BUN & SDMA explained together
Creatinine is just one piece of the puzzle. Vets look at three kidney markers together—BUN, creatinine, and SDMA—to get the full picture of your cat's kidney health.
Cat Kidney Values Quick Reference Chart
| Test | Normal | Mild | Moderate | Severe |
|---|---|---|---|---|
| BUN (mg/dL) | 10-30 | 31-50 | 51-80 | >80 |
| Creatinine (mg/dL) | 0.8-2.4 | 2.5-2.8 | 2.9-5.0 | >5.0 |
| SDMA (µg/dL) | 0-14 | 15-25 | 26-38 | >38 |
One elevated test could be dehydration or stress. Kidney disease diagnosis requires 2+ elevated tests at least 2 weeks apart. SDMA rises earliest (at 25% kidney loss vs 75% for creatinine).
Normal ranges: BUN 10-30, creatinine 0.8-2.4, SDMA 0-14. If your cat's creatinine is 2.8 and SDMA is 18, that's Stage 2 kidney disease—treatable with diet alone if caught now. If creatinine hits 3.5+, you're in Stage 3 requiring medications. The decision point: SDMA >14 or creatinine >2.4 means stop watching and start intervening.
What Vets Focus On
- • SDMA is the early warning — rises before creatinine, often 6-12 months sooner
- • High BUN + normal creatinine = dehydration — recheck after fluids before diagnosing CKD
- • Creatinine >2.8 triggers treatment — prescription diet and phosphate binders start immediately
What Are Cat Kidney Values?
- • BUN (Blood Urea Nitrogen) — A waste product filtered by the kidneys. When kidneys aren't functioning optimally, BUN levels rise.
- • Creatinine — Another waste product closely linked to kidney function. Often considered more reliable than BUN for assessing kidney health.
- • SDMA — An early marker that detects kidney disease before creatinine rises. Learn more in our detailed SDMA guide.
Why Kidney Values Matter in Cats
Cats are particularly prone to chronic kidney disease (CKD), especially as they age. Studies show that up to 30% of cats over 10 years old develop some degree of kidney disease. This is why regular screening for senior cats is so important. Tracking these values helps veterinarians catch kidney problems early and guide treatment decisions that can significantly improve quality of life.
Common Causes of Elevated Kidney Values
- High BUN: Dehydration, high-protein diet, gastrointestinal bleeding, or kidney disease. See our complete BUN guide for details.
- High Creatinine: More directly linked to kidney dysfunction and less affected by external factors
- High SDMA: Sensitive early warning sign of CKD, often elevated before other markers
Chronic Kidney Disease Staging Chart for Cats
| IRIS Stage | Creatinine | SDMA | What It Means | Treatment Focus |
|---|---|---|---|---|
| Stage 1 | < 1.6 | < 18 | Non-azotemic. Kidney disease present but function appears normal. | Identify cause, regular monitoring, kidney-friendly diet. |
| Stage 2 | 1.6 - 2.8 | 18 - 25 | Mild disease. ~33% function lost. Often no symptoms. | Prescription diet, hydration, phosphorus binders. Monitor every 3-6 months. |
| Stage 3 | 2.9 - 5.0 | 26 - 38 | Moderate disease. ~75% function lost. Symptoms appear. | Diet, fluids, phosphorus binders, BP meds, anti-nausea. Monitor monthly. |
| Stage 4 | > 5.0 | > 38 | Severe disease. >75% function lost. Quality of life affected. | Intensive care, frequent fluids, appetite stimulants. Palliative discussions. |
Life Expectancy by CKD Stage
Stage alone doesn't determine prognosis — a Stage 3 cat who drinks well, eats a kidney diet, and has controlled blood pressure often outlives a Stage 2 cat who is managed poorly. That said, median survival times from diagnosis give a realistic starting point:
| IRIS Stage | Creatinine | Median Survival | Key Factors |
|---|---|---|---|
| Stage 1 | < 1.6 mg/dL | Years — often near-normal lifespan | Diet, monitoring, address underlying cause |
| Stage 2 | 1.6–2.8 mg/dL | ~1,000–3,000+ days (3–8+ years) | Phosphorus control is the biggest modifiable factor |
| Stage 3 | 2.9–5.0 mg/dL | ~200–600 days (6 months–2 years) | Hydration, nausea control, blood pressure |
| Stage 4 | > 5.0 mg/dL | ~35–80 days median; highly variable | Quality of life, appetite, uremic signs |
Survival data from Syme et al. (2006) and Boyd et al. (2008). Ranges reflect well-managed cats; individual outcomes vary significantly based on concurrent diseases (hypertension, hyperthyroidism, anemia) and response to treatment.
Phosphorus: The Most Important Number You're Not Watching
Most cat owners focus on creatinine and BUN, but phosphorus may matter more for slowing progression. Elevated phosphorus damages the remaining nephrons directly and accelerates CKD. The IRIS targets:
- • Stage 1–2: Phosphorus < 4.5 mg/dL — achievable with diet alone in most cats
- • Stage 3: Phosphorus < 5.0 mg/dL — often requires phosphate binders (aluminum hydroxide, lanthanum carbonate)
- • Stage 4: Phosphorus < 6.0 mg/dL — binders essential; some cats need multiple types
If your cat's phosphorus is above target for their stage, this is often the single highest-impact change your vet can make. Ask specifically about phosphorus at every CKD recheck — it isn't always discussed unless you raise it.
Phosphorus is controlled mainly through food, so if your cat is above target for their stage the next question is which diet and how to switch. Our guide to the best diet for cats with CKD covers the prescription options and how to transition a picky cat.
Understanding the staging chart helps you interpret your cat's specific results. Here's how to put the numbers together:
Example: Understanding Your Cat's Values
If your cat has BUN 37, Creatinine 2.4, SDMA 18:
- • Creatinine 2.4 suggests Stage 2 CKD (1.6-2.8 range)
- • SDMA 18 is at the borderline (Stage 1-2), confirming mild kidney disease
- • BUN 37 is mildly elevated (normal 10-30), consistent with early kidney dysfunction
- • Action: Start prescription kidney diet, ensure good hydration, recheck in 3-6 months
Important: Staging requires at least two consecutive tests showing elevated values, with at least 2 weeks between tests. One elevated result could be dehydration or stress. SDMA often catches kidney disease earlier than creatinine alone, and staging guides treatment but doesn't predict lifespan—many Stage 2-3 cats live years with proper management.
Have your cat's kidney panel results?
Upload your cat's bloodwork and get instant explanations of creatinine, BUN, and SDMA values. Track trends over time to catch kidney disease early.
Analyze My Cat's Kidney PanelFeeding a Cat With Kidney Disease
Before changing food, be sure of what these numbers mean. Kidney values rise with dehydration as readily as with kidney disease, and a single elevated panel is not a diagnosis. Diet only becomes the lever once your vet has confirmed CKD on a repeat panel with a urine specific gravity to match.
The evidence-based choice: a prescription renal diet. Hill's Prescription Diet k/d is the most studied of them, holding phosphorus to roughly 0.3–0.5% on a dry matter basis against 1.0–1.5% in ordinary cat food. Phosphorus restriction is the single dietary factor with the strongest evidence behind it in CKD. These diets need your vet's authorization, which you can supply when ordering through Petco's veterinary range rather than making a separate trip.
Shop Prescription Renal Diets →If you don't have the authorization yet: a renal diet needs a vet's sign-off before any retailer will sell it to you. An online vet can review your cat's bloodwork and write it without a clinic visit, which is usually faster than waiting for an appointment.
Talk to a Vet Online →If a prescription diet is not an option yet: Smalls is one of the few fresh cat food companies publishing real nutrient data, running roughly 0.37–0.39% phosphorus as fed, about 1.13–1.39% dry matter. Set that against the numbers above and the limit is plain — it is not a renal diet and not a low-phosphorus food, it sits at the lower end of the ordinary range. What it offers is high moisture, portion control, and figures you can check against your vet's guidance. That makes it worth considering in two narrow cases: a Stage 1 cat being managed without a therapeutic diet, or a cat refusing renal food outright, where the real alternative is not eating. IRIS guidance puts a therapeutic diet from Stage 2 onward, so this stops being appropriate as CKD progresses.
See Smalls Recipes →The full guide to what to feed a cat with kidney disease →
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Signs of Kidney Problems in Cats
- • Increased drinking and urination — often the first sign owners notice
- • Weight loss — despite normal or increased appetite
- • Reduced appetite — becoming pickier about food
- • Vomiting or lethargy — from toxin buildup
- • Bad breath — chemical odor from kidney dysfunction
If your cat has not been diagnosed yet, this is the moment to price cover
Kidney values rise with dehydration as readily as with disease, and a single elevated panel is not a diagnosis. The window closes at the diagnosis, not at the first abnormal number. Plans start at $9/month.
How “pre-existing” actually works: insurers exclude anything your pet has already shown signs of before the policy starts or during its waiting period. A diagnosis is not required — a note in the record can be enough on its own.
Conditions that are curable generally stop counting once your pet has been free of symptoms and treatment for a set period, commonly 180 days. Chronic ones — kidney disease, diabetes, heart disease — do not. So the moment that matters is before the next panel rather than after it, and whether a value already flagged in the record counts is a judgement your insurer makes when a claim is filed. Read the policy's own definition before buying.
We may earn a commission if you purchase through this link, at no extra cost to you.
What Happens Next?
Your veterinarian may recommend:
- • Repeat bloodwork to confirm trends and rule out temporary elevations
- • Urine testing to assess kidney concentration ability
- • Imaging (ultrasound) to evaluate kidney structure
- • Prescription kidney diets that are lower in protein and phosphorus
- • Supportive medications including fluids, phosphorus binders, and appetite stimulants
- • Blood pressure monitoring as hypertension often accompanies kidney disease
Key takeaway: Kidney values show how well your cat's kidneys are functioning. Mild changes may only need monitoring, while severe or persistent changes guide treatment decisions. Early detection and management can significantly slow disease progression.
Monitor Your Cat's Kidney Health
Upload your cat's bloodwork into VetLens and get:
- ✓ Plain-English explanations of BUN, Creatinine, and SDMA
- ✓ Context on whether changes are due to dehydration, diet, or CKD
- ✓ Suggested questions to ask your vet
- ✓ Tailored diet and supplement recommendations
Frequently Asked Questions
What is SDMA and why is it important?
SDMA is an early marker of kidney function that often rises before creatinine. It can detect kidney disease when only 25% of kidney function is lost, compared to creatinine which typically rises after 75% loss.
What causes high BUN in cats?
High BUN can result from kidney disease, dehydration, high-protein diet, or gastrointestinal bleeding. Your vet will consider other values and clinical signs to determine the cause.
What is a dangerous creatinine level?
Values above 2.4 mg/dL are considered abnormal. Levels above 4.0 mg/dL often indicate advanced kidney disease requiring intensive management.
Can kidney disease be treated?
While there's no cure for chronic kidney disease, proper diet, medications, and supportive care can slow progression and significantly improve quality of life. Many cats live years with well-managed kidney disease.
What creatinine level is dangerously high in cats?
Creatinine above 5.0 mg/dL marks Stage 4 CKD — the most severe category. At this level, over 75% of kidney function is lost and cats often show uremic signs: vomiting, not eating, severe lethargy, and mouth ulcers. Values between 3.0–5.0 (Stage 3) are serious but many cats respond well to aggressive management. A single high reading isn't always the full picture — dehydration can temporarily push creatinine up by 0.5–1.0 mg/dL, so vets recheck after rehydration before staging.
My cat has Stage 3 kidney disease — how long do they have?
Stage 3 (creatinine 2.9–5.0 mg/dL) has a median survival of roughly 200–600 days from diagnosis in published studies, but this range is wide. Cats at the lower end of Stage 3 who eat well, maintain weight, have controlled blood pressure and phosphorus, and receive subcutaneous fluids regularly often exceed these medians significantly. The trajectory matters as much as the current number — a cat holding stable at creatinine 3.2 for 18 months has a different prognosis than one who went from 2.5 to 3.2 in 3 months.
What does high BUN mean if creatinine is normal?
BUN elevated with normal creatinine almost always means dehydration, not kidney disease. BUN rises faster with dehydration and dietary protein than creatinine does. Your vet will typically recheck after IV or subcutaneous fluids — if BUN normalizes and creatinine stays normal, the kidneys are fine. If both rise together and stay elevated on a recheck 2+ weeks later, that points toward CKD.
When should I consider euthanasia for a cat with kidney disease?
There's no creatinine number that automatically means it's time. The decision centers on quality of life: Is your cat eating? Comfortable? Interested in interaction? Able to groom? Uremic signs — persistent vomiting, not eating for days, hiding, seizures, severe weakness — indicate suffering that treatment can no longer control. Many vets use quality-of-life scoring tools (like the HHHHHMM scale) to help make this assessment more objective. When treatment stops buying good days and only extends difficult ones, that's usually when the conversation shifts.
Related Reading
How to Read Cat Blood Test Results
Comprehensive guide to understanding all your cat's bloodwork
SDMA in Cats
Why this early kidney marker is so important
BUN Levels in Cats
What high BUN means and when it's concerning
Chronic Kidney Disease in Cats
Stages, treatment, and long-term management
Cat Liver Enzymes Explained
Liver function is often tested alongside kidney values