Cortisol

Specimen requirements

Sample type: Serum (Serum)

Collection requirements: No special requirements

Cost

Price on application

Turnaround time

Please see Turnaround times

Analytical method

Immunoassay - Indirect / Competitive

Analysis undertaken at these site(s)

• John Radcliffe Hospital
• Churchill Hospital
• Horton General Hospital

Reference intervals

In adult patients who are not taking steroid treatment:

9am cortisol <100nmol/L is suggestive of adrenal insufficiency

9am cortisol >350nmol/L excludes adrenal insufficiency

9am cortisol between 100 and 350nmol/L may be normal, and cannot be used to exclude or diagnose adrenal insufficiency

9am cortisol <50 nmol/L after overnight dexamethasone suppression exclude endogenous Cushing's syndrome.

A random (non-9am) cortisol or a value when the patient is taking steroid treatment is uninterpretable

For guidance on interpretation of cortisol results, please contact Endocrinology Advice and Guidance via eRS.