Cortisol/Creatinine ratio

LABOKLIN Service ID: 183


Diagnosis

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

Material

Morning urine 1 ml

Execution

  • 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
Parameter

Cortisol, creatinine

Species list

Dog

Duration

1 day

Assessment

  • 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).