The UCCR is a useful screening test for canine hyperadrenocorticism as a low (normal) result makes Cushing's unlikely, with approximately 90% sensitivity. It is useful in those cases where hyperadrenocorticism is unlikely but needs to be definitely excluded. The test has low specificity as there are a lot of false positives. Further tests are needed to confirm that a high result is due to hyperadrenocorticism. It is thought that the test has similar sensitivity and specificity in cats but there are few published reports.
The urinary cortisol:creatinine ratio may be used as a screening test on urinary samples collected at home by the owners. Patients with elevated UCCR may then be tested with the low dose dexamethasone test.
- Ratio < 17.5 x 106 Cushing's is unlikely
- Ratio > 17.5 x 106 Cushing's may be present
Canine and feline
- Collect a morning urine sample. To avoid false positives, stress should be minimised in the 24 hours prior to collection, and avoid testing unwell patients.
- Submit sample with a request for urinary cortisol and creatinine ratio.