• Patients with hyponatraemia
• Patients with unexplained hypotension
• Patients with hypoglycaemia not in the context of insulin or sulfonylurea use
• Patients who have pituitary disease (note in acute setting results may not be interpretable)
• Patients who have new pigmentation - particularly of scars and gums
• Weaning long term steroids in a patient (see steroid bundle)

What if my patient is taking steroids?
Patients who are taking prednisolone at a dose of >4mg/daily, hydrocortisone >15mg daily, dexamethasone > 0.5mg daily or methylprednisolone >3mg daily are on supraphysiological doses of steroid which can suppress their own steroid production. Hydrocortisone can be picked up on the cortisol assay but the other steroids will not be and patients on these doses of steroid will have appropriately low cortisol levels when measured. Please do not check a cortisol in patients on more than these doses of steroids or equivalent

Morning Cortisol Tests

Cortisol is best checked in the morning before 10am.

Morning Cortisol >425nmol/L - excludes adrenal insufficiency

Morning Cortisol >275nmol/L but <425nmol/L - Adrenal insufficiency unlikely. If concurrent critical illness or high index of clinical suspicion please discuss with Endocrinology on call. 

Morning cortisol of <275nmol/L - Adrenal insufficiency possible. Confirm with short synacthen test (SST).

Short Synacthen Test (SST)

1: Draw a blood sample (brown tube) and send to lab for cortisol at time 0 minutes

2: Inject 250micrograms (one ampoule) of synacthen either intravenously or intramuscularly

3: Draw a second blood sample (brown tube) and send to lab for cortisol at time 30 minutes

4: Ideally the labels should be printed at the time of blood taking to enable appropriate interpretation of results.

5: Interpret result: A cortisol of >430nmol/L in the second sample suggests intact adrenal function.

Synacthen is not kept on most wards but can be ordered the same day from pharmacy. Ideally synacthen tests are performed in the morning but will still be reliable in the afternoon.

A SST should NOT be performed in a patient who is within six weeks of pituitary surgery or injury, or in patients in whom there is a suspicion of pituitary apoplexy as it is not reliable. Please discuss any concern with adrenal insufficiency in these patient with the endocrine team on call. If there is a suspicion of pituitary apoplexy please call the endocrine on-call team out of hours as a matter of urgency.