Urinary free cortisol

Urinary free cortisol measurements are used primarily in the diagnosis of hypercortisolism caused by Cushing syndrome.

Reference ranges for urinary free cortisol vary by age, as follows:

  Age 0-2 years - Not established

  Age 3-8 years - 1.4-20 µg/24 h

  Age 9-12 years - 2.6-37 µg/24 h

  Age 13-17 years - 4-56 µg/24 h

  Age 18 years or older - 3.5-45 µg/24 h

Conversion factor

Cortisol: µg/24 h X 2.76 = nmol/24 h (molecular weight = 362.5)