Lab value · BUN
Blood Urea Nitrogen in cats, explained
BUN measures urea, a waste product from breaking down protein. The kidneys remove it, so it often rises with kidney disease.
What a higher blood urea nitrogen can mean
A higher BUN can come from reduced kidney function, dehydration, a high-protein meal before the test, or bleeding in the gut. High BUN is often linked to nausea.
What a lower blood urea nitrogen can mean
A lower BUN can reflect better hydration, a lower-protein diet, or improved kidney function.
Why it matters in kidney disease
- BUN is not used for IRIS staging, but it often rises alongside creatinine in CKD.
- High BUN is linked with uremic nausea, poor appetite and mouth ulcers, so it helps your vet understand how your cat may be feeling.
- A protein-rich meal before the blood draw or bleeding in the gut can also raise BUN.
Questions to ask your vet
Ask your vet
- Could my cat’s BUN be contributing to nausea or poor appetite?
- Does my cat’s diet need adjusting?
Decode your cat’s BUN
Enter your cat’s values and get a plain-English summary, IRIS reference bars and questions for your vet.
Frequently asked questions
What is Blood Urea Nitrogen in a cat blood test?
BUN measures urea, a waste product from breaking down protein. The kidneys remove it, so it often rises with kidney disease.
What does a high blood urea nitrogen mean in cats?
A higher BUN can come from reduced kidney function, dehydration, a high-protein meal before the test, or bleeding in the gut. High BUN is often linked to nausea.
What does a low blood urea nitrogen mean in cats?
A lower BUN can reflect better hydration, a lower-protein diet, or improved kidney function.
What is a normal blood urea nitrogen level for a cat?
A typical feline reference interval is about Example only: 16 – 36 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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