IRIS Stage 4 · Severe
IRIS Stage 4 kidney disease in cats: what it means
Kidney values are markedly raised and cats are more likely to feel unwell. Care focuses on comfort, appetite, hydration and quality of life, in close partnership with your vet.
Please read first
These are reference ranges, not a stage. Only your vet can stage CKD — in a cat that is clinically stable and well hydrated, using results from at least two occasions and the whole clinical picture. The values below describe the range IRIS associates with Stage 4. A single test result in this range does not mean a cat “is” Stage 4.
The values IRIS associates with Stage 4
| Blood creatinine | > 5.0 mg/dL (> 440 µmol/L) |
|---|---|
| SDMA | > 38 µg/dL |
| Phosphorus target | 2.5 – 6 mg/dL |
Source: IRIS Staging of CKD (modified 2023) — iris-kidney.com; phosphate targets: 2026 iCatCare consensus guidelines.
What care often looks like
Every cat is different, and your vet will tailor care to yours. At this stage, care often includes:
- Care usually focuses on comfort: appetite, nausea control, hydration and keeping your cat warm and calm.
- Some cats benefit from more intensive support such as hospital fluids, or a feeding tube if eating is hard. Your vet can explain what might help your cat.
- Tracking good days and bad days can help you and your vet see the bigger picture.
- Hospice-style care at home is an option many families choose. Talk with your vet about what you’re seeing.
How long do cats live at Stage 4?
Values in the Stage 4 range mean the kidneys are working much less than normal, and cats are more likely to feel unwell. Some cats still have good stretches of time with supportive care. Your vet can help you understand what to expect and how to keep your cat comfortable.
Substaging: urine protein and blood pressure
IRIS also “substages” every cat with CKD by protein in the urine (UPC) and by blood pressure, because both affect care. These apply at any stage.
| UPC | Substage |
|---|---|
| < 0.2 | Non-proteinuric |
| 0.2 – 0.4 | Borderline proteinuric |
| > 0.4 | Proteinuric |
| Systolic (mmHg) | Substage |
|---|---|
| < 140 | Normotensive |
| 140 – 159 | Prehypertensive |
| 160 – 179 | Hypertensive |
| ≥ 180 | Severely hypertensive |
Questions to ask your vet
Ask your vet
- What can we do to keep my cat comfortable?
- What signs of discomfort should I watch for at home?
- How will we know if a treatment is helping?
- Can we talk about quality of life and what support is available?
Not sure where the numbers sit?
Type your cat’s creatinine and SDMA into the free Lab Decoder to see them on the IRIS reference bars.
Frequently asked questions
What does IRIS Stage 4 mean for a cat?
Kidney values are markedly raised and cats are more likely to feel unwell. Care focuses on comfort, appetite, hydration and quality of life, in close partnership with your vet. Only your vet can stage your cat, using repeated tests on a stable, well-hydrated cat.
What creatinine level is IRIS Stage 4 in cats?
IRIS associates a blood creatinine of > 5.0 mg/dL (> 440 µmol/L) with Stage 4 in cats, alongside an SDMA of > 38 µg/dL.
What is the life expectancy for a cat with Stage 4 kidney disease?
Values in the Stage 4 range mean the kidneys are working much less than normal, and cats are more likely to feel unwell. Some cats still have good stretches of time with supportive care. Your vet can help you understand what to expect and how to keep your cat comfortable.
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