Lab value · CREA
Creatinine in cats, explained
Creatinine is a waste product made by muscles. Healthy kidneys filter it out of the blood, so when kidney filtering drops, creatinine rises.
What a higher creatinine can mean
A higher creatinine usually means the kidneys are filtering less — though dehydration can raise it temporarily, and lab-to-lab differences are common.
What a lower creatinine can mean
A lower creatinine can reflect better hydration or improved kidney filtering. Cats that lose muscle can also show lower creatinine than their kidney function would suggest.
Why it matters in kidney disease
- Creatinine is the marker IRIS has used longest to describe where kidney values sit. It is usually measured alongside SDMA, BUN and a urine test.
- It only rises noticeably once a large share of kidney function has been lost, so a normal creatinine does not rule out early kidney changes.
- Because muscle makes creatinine, thin or older cats with less muscle can show a lower number than their kidneys alone would produce. SDMA helps here.
- Dehydration raises creatinine temporarily. Vets often recheck once a cat is well hydrated before drawing conclusions.
IRIS reference bands
IRIS publishes reference bands for creatinine in cats. A value in a band is not a diagnosis: 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.
| IRIS stage | Creatinine (mg/dL) | µmol/L |
|---|---|---|
| Stage 1 | < 1.6 | < 140 |
| Stage 2 | 1.6 – 2.8 | 140 – 250 |
| Stage 3 | 2.9 – 5.0 | 251 – 440 |
| Stage 4 | > 5.0 | > 440 |
Source: IRIS Staging of CKD (modified 2023) — iris-kidney.com; phosphate targets: 2026 iCatCare consensus guidelines.
What does my cat’s number mean?
- A creatinine of 1.4 mg/dL (about 124 µmol/L) is in the range IRIS associates with Stage 1.
- A creatinine of 1.8 mg/dL (about 159 µmol/L) is in the range IRIS associates with Stage 2.
- A creatinine of 2.0 mg/dL (about 177 µmol/L) is in the range IRIS associates with Stage 2.
- A creatinine of 2.5 mg/dL (about 221 µmol/L) is in the range IRIS associates with Stage 2.
- A creatinine of 3.0 mg/dL (about 265 µmol/L) is in the range IRIS associates with Stage 3.
- A creatinine of 4.0 mg/dL (about 354 µmol/L) is in the range IRIS associates with Stage 3.
- A creatinine of 5.5 mg/dL (about 486 µmol/L) is in the range IRIS associates with Stage 4.
Whatever the number, one result is a snapshot. Your vet will look at hydration, the trend over time and other tests together.
Questions to ask your vet
Ask your vet
- Is this change meaningful, or within normal day-to-day variation?
- Was my cat well hydrated when this sample was taken?
- When should we recheck creatinine?
Decode your cat’s CREA
Enter your cat’s values and get a plain-English summary, IRIS reference bars and questions for your vet.
Frequently asked questions
What is Creatinine in a cat blood test?
Creatinine is a waste product made by muscles. Healthy kidneys filter it out of the blood, so when kidney filtering drops, creatinine rises.
What does a high creatinine mean in cats?
A higher creatinine usually means the kidneys are filtering less — though dehydration can raise it temporarily, and lab-to-lab differences are common.
What does a low creatinine mean in cats?
A lower creatinine can reflect better hydration or improved kidney filtering. Cats that lose muscle can also show lower creatinine than their kidney function would suggest.
What is a normal creatinine level for a cat?
A typical feline reference interval is about Example only: 0.6 – 2.4 mg/dL. Use the range printed on your cat’s report — it differs between labs., but every lab sets its own range. The range printed on your cat’s report is the one to use.
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