By The Pawline veterinary teamVeterinary-reviewed by Alastair Greenway, BVM&S MRCVS · 25 July 2026
The UCCR measures cortisol in urine, corrected for concentration, giving an integrated picture of cortisol output rather than a single stressed snapshot. It is a very sensitive screen for Cushing's disease — excellent at ruling it OUT, but poor at ruling it in, because stress alone raises it.
Measuring cortisol in blood has a well-known problem: it surges with stress, so a single sample from a vet visit is nearly uninterpretable. The urine cortisol:creatinine ratio sidesteps some of that. Cortisol is excreted into urine continuously, so a urine sample reflects cortisol output integrated over several hours rather than one instant. Dividing by urine creatinine cancels out how dilute the sample is — the same trick the UPC uses — giving a single dimensionless number.
The UCCR measures cortisol output integrated over hours, corrected for urine concentration — a sensitive screen, best at ruling Cushing's out.
Crucially, the sample should be collected at home, calmly, ideally a morning sample after a couple of quiet days — because a sample taken at the clinic reintroduces exactly the stress the test is trying to avoid.
The key property: rules out, doesn't rule in
The UCCR's defining characteristic is that it is highly sensitive but poorly specific for Cushing's disease (hyperadrenocorticism):
A normal UCCR makes Cushing's very unlikely. This is its real value — a cheap, non-invasive, owner-collected test that can largely exclude the disease and spare a pet a more involved work-up.
A raised UCCR does not confirm Cushing's. Stress and virtually any non-adrenal illness can raise it — kidney disease, diabetes, and general illness among them. A high result means "Cushing's is not excluded", not "Cushing's is present".
So a raised UCCR is a doorway to definitive testing — the LDDST or ACTH stimulation test — never an endpoint. Using it as a diagnosis would over-treat a great many stressed or unwell dogs.
Other uses
The UCCR is sometimes used in an extended protocol (with dexamethasone given at home) to help distinguish pituitary-driven from adrenal-driven Cushing's once the diagnosis is established. It has also been explored, less commonly, in investigating suspected Addison's disease, where a comfortably normal result argues against cortisol deficiency.
In chronic disease
Because it is non-invasive and owner-collected, the UCCR is convenient for screening, but the monitoring of treated Cushing's patients is generally done with ACTH stimulation testing (or equivalent protocols) and clinical signs rather than UCCR. Its home is at the front of the diagnostic pathway, not the follow-up.
Cat vs dog
The UCCR is chiefly a canine test, reflecting how much more commonly Cushing's is diagnosed in dogs. It has been described in cats, where feline Cushing's is uncommon and characteristically linked to poorly-controlled diabetes, but the interpretive experience is far deeper in dogs. In both, the stress and illness caveats apply.
About the reference range
This page shows no range strip. The UCCR is a derived ratio whose cut-offs are laboratory-specific, and Pawline draws a band only where it holds a verified interval. Read your result against the reference on your own report, noting how and where the sample was collected.
For orientation only: one widely-used screening cut-off is >20 (Zoetis interpretive guide / 2023 AAHA endocrinopathy guidelines), applied to both dogs and cats — but it is a rule-out, not a rule-in: a value under it makes Cushing's unlikely, while a value over it is only supportive because many non-adrenal illnesses (and the stress of a vet-collected sample) push it up. The exact number is also scaling- and lab-dependent — other laboratories quote thresholds such as >15 or >30 in ×10⁻⁶ units — so the denominator scaling must match the reporting lab. In cats it is the recommended first-line screen; collect the urine calmly at home. Read your own report's cut-off.
What to do next
If Cushing's is suspected, a calmly collected home urine sample for UCCR is a sensible, low-stress first step: a normal result largely closes the question. A raised result should be followed by definitive dynamic testing (LDDST or ACTH stimulation) with your vet, and interpreted in the light of any other illness — because on its own, a high UCCR frequently means nothing more than that your dog was unwell or unsettled.
This page is educational and is not a diagnosis. Lab results are interpreted in the full clinical context by your veterinary surgeon; a single value rarely tells the whole story.
