Cortisol/Creatinine Ratio

Diagnosis of Cushing’s disease including differentiation between adrenal and pituitary forms.

Morning urine 1 ml

• Collection of morning urine day 1 = sample 1
• Collection of morning urine day 2 = sample 2
• Administration of dexamethasone on day 2: orally 3 x 0.1 mg/kg bdw throughout the day
• Collection of morning urine day 3 = sample 3

Cortisol, creatinine

Dog

1 day

• Interpretation of the ratio of day 1 and day 2:
  < 40: Normadrenocorticism, Cushing’s disease is unlikely.
  40 – 60: Questionable result
  > 60: Hyperadrenocorticism is possible and should be verified by a low-dose dexamethasone test.
• Interpretation of the ratio of day 3:
  (An increased ratio on day 1 and day 2 is a prerequisite)
  > 50% of the average value of the first two samples indicate a cortisol-producing adrenocortical tumour. The presence of nonsuppressible pituitary Cushing’s disease is possible.
  < 50% of the average value of the first two samples indicate a pituitary-dependent Cushing’s disease or another disease which causes increased cortisol secretion (diabetes, stress, gastrointestinal diseases, diseases with protein loss).