Specimen requirements
Sample type: Serum (Serum)
Collection requirements: No special requirements
Cost
Price on application
Turnaround time
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 on steroid treatment,
- 9 a.m. cortisol <100 nmol/L suggests adrenal insufficiency
- 9 a.m. cortisol >400 nmol/L makes adrenal insufficiency unlikely
- For 9 a.m. cortisol of 100-400, consider a short synacthen test
- Midnight cortisol <50 nmol/L excludes endogenous Cushing's
- 9 a.m. cortisol <50 nmol/L after overnight dexamethasone suppression excludes endogenous Cushing's syndrome. For advice, please consult Endocrinology.
A random (e.g. non-9.00 a.m.) cortisol or a value when patient is on steroids is uninterpretable.
