Hypercortisolism Diagnosis and Imaging

Diagnosis and Radiological tests

There are four main questions your doctor will try to answer to determine if you might have Cushing syndrome:

  1. Are you producing too much cortisol? Collecting your urine for 24 hours and measuring the cortisol can tell your doctor how much cortisol was made over the day.
  2. Do you have a low cortisol level in the late evening? Checking the amount of cortisol in your saliva just before going to sleep at night tells your doctor whether your levels are following a normal ‘predictable’ pattern.
  3. Does the amount of cortisol produced by your body decrease normally after giving a dose of artificial steroid? The low dose (1mg) dexamethasone suppression test will test to see if your body responds normally to an increase in steroid levels.
  4. Is your ACTH level low, normal or high? A low ACTH level indicates there is potentially a higher than normal amount of cortisol being produced by the adrenal glands. A high ACTH level suggests the pituitary gland or a site elsewhere in the body is producing too much ACTH, and this can cause increased levels of cortisol in the body.

Once the diagnosis is made, the next step is to determine the cause. If the ACTH level is high, you will need to have additional tests to determine if there is a pituitary or ectopic tumor.

The results of the laboratory testing will determine what type of imaging is needed. If a pituitary tumor is suspected, then a CT scan or MRI of the brain will be ordered. If it is believed that excess cortisol levels are caused by a tumor in the adrenal gland(s), a CT scan or MRI of the abdomen will likely be ordered. If an ectopic ACTH-producing tumor is suspected, then a CT scan, MRI, PET CT or DOTATATE scan of the chest, abdomen, and pelvis will likely be ordered.