Sample type: Serum
Test name: Cortisol a.k.a. dexamethasone suppression test
Condition / Indication: Addisons / Cushings
Special precautions & notes: Indications - suspicion of adrenal insufficiency. For diagnosis a short synacthen test is advised. For a short synacthen test, please ensure that a short synacthen test (rather than 3 separate cortisols) is requested. Multiple labels will be printed for the time points required.
Reference range: 8-10 am cortisol > 300 nmol/l usually considered to exclude Addisons unless on oestrogens or systemically unwell. A short synacthen test may be required to exclude Addisons: a stimulated cortisol (at either 30 or 60 minutes) ≥450 nmol/L excludes adrenal insufficiency, and in pregnant ladies, or those taking OCP, a higher threshold of 600 nmol/L applies. For investigation of Cushings, see document below to aid test selection.
Container: Serum (Gold top)
Ideal volume (mL): 5 mL
Referred outside NBT for analysis? No
Discipline: Clinical Biochemistry
Section: Automated Laboratory
Turnaround time: 1 day