Creatinine
Chemistry ·Also called: CREA, CRE, creatinine serum, kidney value
What it is
Muscle produces creatinine continuously as a by-product of energy use. Healthy kidneys clear it efficiently, so the blood level stays remarkably stable in a given animal. It is less affected by diet than BUN.
Why your vet measures it
Creatinine underpins the staging of chronic kidney disease and the monitoring of every pet on kidney treatment. Its weakness is muscle dependence: a heavily muscled dog runs higher and a thin, elderly cat with wasted muscle can have 'normal' creatinine despite significant kidney loss.
What a high result can mean
- Chronic kidney disease, the most common cause in older cats and dogs
- Acute kidney injury from toxins — antifreeze, lilies in cats, grapes in dogs, some medications
- Dehydration or reduced blood flow to the kidneys
- A urinary obstruction preventing urine leaving the body
- Large muscle mass, which raises the baseline without disease
What a low result can mean
- Loss of muscle mass from age, illness or malnutrition
- Over-hydration
- Not usually a concern in itself, but it can mask kidney disease
Dogs and cats differ
Greyhounds and other sighthounds normally run creatinine above the standard canine range because of their muscle mass, and treating that as kidney disease is a well-known trap. In older cats, the opposite trap applies: muscle wasting can keep creatinine looking acceptable while the kidneys decline, which is a large part of why SDMA was introduced.
Questions worth asking your vet
- How does this compare with my pet's own previous results?
- Was the urine concentrated or dilute at the same time?
- Given my pet's breed and body condition, is this value what you would expect?
- What IRIS stage does this put my pet in, and what changes now?
Related terms
See this value explained on your pet's own report
Upload the lab report or X-ray and get every value explained in the context of your own dog or cat — in minutes.
Explain my pet's results