It may take time to be diagnosed with Cushing's disease
There is a process to diagnosing Cushing's disease, and it normally takes time. People may have symptoms from excessive cortisol levels for some time before Cushing's syndrome or Cushing's disease is suspected. Different tests can identify if your symptoms are the result of excessive cortisol. When these tests confirm that there is excess cortisol in the body, additional tests are used to determine if this hypercortisolism is caused by Cushing's disease or a different form of Cushing's syndrome. Each test may be performed multiple times because the level of cortisol in your body can change throughout the day. The only way to be sure results are accurate is to repeat the tests.
The process of diagnosing Cushing's disease
There are generally 3 phases in the diagnostic process and you will likely see more than 1 doctor, including an endocrinologist.
Phase I: Confirm clinical suspicion For more information about each test, click its name.
For patients who respond to and can tolerate immediate release Sandostatin® Injection:
The indicated starting dose of Sandostatin® LAR Depot is 20 mg q28d (no washout period)
With appropriate dosing, steady-state drug levels typically achieved at 3 months
Medical history (drug history)
Measures the likelihood that your symptoms are caused by hypercortisolism and identifies possible causes that can be evaluated with medical tests. Due to the complexities associated with the diagnosis of Cushing's disease, it is very important to be honest when you answer these questions.
Medical history (drug history)
To better understand your health and symptoms, your doctor or nurse will ask you specific questions, such as:
Are you taking any medications?
What types of food do you eat and how often do you eat them?
How often do you exercise?
Have you gained weight suddenly? (you may be asked to show an old photograph of yourself)
Measures if you have the symptoms that are known to be caused by hypercortisolism.
Your doctor may look for:
Purplish streaks on your body (called striae)
Fatty tissue around your mid-section
Thinning of your arms and legs
Fatty tissue that creates a hump on your back
Redness or roundness in your face
Bruises on your body
Thinning of your skin
Excessive facial/hair growth (hirsutism) if you're female
Medical conditions that are unusual for a patient's age
— High blood pressure (called hypertension)
— High cholesterol2
— Heart disease
Your doctor or nurse will examine your entire body to look for specific physical signs of Cushing's disease and may do some tests to better understand your symptoms.
Phase II: Confirm hypercortisolism Medical tests will be performed to measure the level of cortisol in the body. These tests should only be done when a form of Cushing's syndrome (including Cushing's disease) is suspected. For more information about each test, click its name.
Measures the level of cortisol in your urine over a 24-hour period.
If the levels are too high, then you may have Cushing's disease or Cushing's syndrome
This test is often used because it only measures the type of cortisol that causes Cushing's disease, called "circulating cortisol," and may be more accurate than other tests that measure cortisol levels
24-hour urinary free cortisol (UFC)
You will have to keep a container with you at all points during the 24-hour period to collect your urine. Make sure to store the container in a cold place such as a cooler or refrigerator.
Tell your doctor if you have a kidney condition because it may affect your test results
Don't drink excessive amounts of fluids or use any glucocorticoid medications, like steroid-containing skin or hemorrhoid creams, during the 24-hour period
The urine will then be given to a lab for testing.
At least two measurements need to be taken because UFC levels in a patient with Cushing's syndrome or Cushing's disease can be variable.
Please follow all written and verbal instructions provided by your doctor.
You will likely need to spend 48 hours at a hospital or specialty center when this test is performed. A healthcare professional will take a blood sample from you at night while you are staying at the hospital or center. An indwelling line is commonly used to draw blood.
Phase III: Determine if Cushing's disease is the cause of hypercortisolism For more information about each test, click its name.
Measures the level of ACTH in the blood that is close to the pituitary gland compared with the level of ACTH in the blood in the periphery.
If the ACTH level in the blood sample near your pituitary is substantially higher than the ACTH level in the blood sample from your peripheral circulation, then it is very likely that you have a tumor in your pituitary gland (Cushing's disease)
A specialist will insert two small tubes (called catheters) into your femoral vein (the vein in the inner thigh in the groin region) and pass it up the vein to your head. Another catheter (called the periphery catheter) will be inserted in a different location (such as your forearm). You will be given a medication to numb the area where the tube is placed in your body.
You may experience some discomfort when the tubes are in place
You are given an injection of CRH and blood samples are taken from both sides of your pituitary as well as from the periphery to measure the levels of ACTH.
The needle used to draw blood may cause swelling or bruising.
This test is more invasive than the others and often recommended only after it is known that you have too much cortisol in your blood.
Measures how the level of cortisol in your blood responds to dexamethasone
If your blood level of cortisol stays the same, you may have Cushing's disease or Cushing's syndrome
Helps determine if an ACTH-producing tumor is on the pituitary (Cushing's disease) or somewhere else (ectopic Cushing's syndrome)
High-dose dexamethasone suppression test
There are several versions of this test but all involve taking dexamethasone and then visiting your doctor, who will take a blood sample. It is thought to be more accurate than the low-dose dexamethasone test.
Version 1: you take 0.5 mg or 2 mg of dexamethasone in pill form every 6 hours for 2 days
Be sure to take the dexamethasone pills at the correct time
Version 2: you take 8 mg of dexamethasone in pill form 1 night before going to bed
Be sure to take the dexamethasone pill at the correct time
Version 3: you are given an IV injection of 4 mg to 7 mg dexamethasone
The needle used to draw blood may cause swelling or bruising