Cushing's Syndrome Diagnosis
When making a Cushing's syndrome diagnosis, a doctor typically reviews the patient's medical history and conducts a physical exam. The next step in diagnosing Cushing's syndrome usually involves a urine test to determine if the patient's body is producing excess levels of the hormone cortisol. If so, further tests are done to determine the cause. Tests used to make a definite Cushing's syndrome diagnosis may include biochemistry tests, imaging scans, and catheterization procedures.
In order to make a Cushing's syndrome diagnosis, the doctor will usually ask a number of questions concerning a person's medical history, including questions about:
- The patient's current symptoms
- Whether there is a family history of any medical problems
- Any medicines the patient is taking.
The doctor will also usually perform a physical exam, looking for any signs of Cushing's syndrome. If these suggest Cushing's syndrome, the doctor will order certain tests.
Tests used for diagnosing Cushing's syndrome follow a two-step process. First, doctors order tests are to see if there is too much cortisol in the body. If these tests indicate that Cushing's syndrome is present, then additional tests are done to discover the cause of the extra cortisol.
The first test often used to diagnose Cushing's syndrome is a urine test. This urine test measures how much cortisol is being produced (this is called a 24-hour urinary free cortisol level test).
If the level of cortisol indicates possible Cushing's syndrome, the doctor will order other tests to discover which of the possible Cushing's syndrome causes may be responsible. These tests may include:
- Biochemistry tests
- Imaging scans
- Catheterization procedures.
In these tests, the doctor may recommend the dexamethasone suppression test, the CRH stimulation test, or both. The dexamethasone suppression test involves taking a man-made cortisol by mouth for one or two days (depending on the test), during which time cortisol levels in the blood and urine are measured. The CRH stimulation test involves receiving an injection of the corticotropin-releasing hormone (CRH), followed by a blood test, to see if there is a rise in the levels of ACTH (adrenocorticotropin) and cortisol.
In some cases, your doctor may first order a dexamethasone suppression test instead of a 24-hour urinary free cortisol level test to help diagnose Cushing's syndrome.