Cushing's syndrome can be difficult to diagnose because a variety of factors-from
the time of day to a temporary illness-can lead to a higher-than-average
cortisol level in people who do not have Cushing's
syndrome. It also can be hard to pinpoint the cause. This is important,
because treatment depends on the cause. You may need to see an
endocrinologist (a doctor who specializes in hormone
disorders) to diagnose or treat Cushing's syndrome.
Cushing's syndrome, your doctor will ask about your
medical history and do a
physical exam. He or she can usually find out
from these exams whether
corticosteroid medicine is causing the condition. If
it is, other tests usually are not done and your doctor will consider changing
It is possible that the main title of the report Addison's Disease is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
If you are not taking steroid medicine or your
doctor believes something other than steroid medicine is causing Cushing's
syndrome, you will have laboratory tests to check your level of cortisol. These
A cortisol test, which may be done on a sample
blood or on a sample of
urine collected over a 24-hour period.
overnight dexamethasone suppression test using a low
dose of steroid (often done to reconfirm a cortisol test). This test is most
commonly done on a sample of blood, but a more extensive form of the test may
involve both blood and urine samples.
A test to measure cortisol in the saliva in the evening may
If the first tests show that too much ACTH is causing
Cushing's syndrome, other tests may be needed to find out its source. These
Inferior petrosal sinus sampling (IPSS) to find
out whether too much ACTH is being released from the pituitary gland. During
IPSS, a small tube (catheter) is used to collect samples from blood vessels
near the brain. If these blood samples show high levels of ACTH, it usually
means that the pituitary gland is the source of excess ACTH. The IPSS is
often used with the CRH stimulation test.
Computed tomography (CT scan) and
magnetic resonance imaging (MRI) of the chest or
pituitary gland, which may help locate a tumor producing ACTH. But sometimes
the tumor may be too small to detect with a CT scan or an MRI. A CT and MRI of
the adrenal gland may also be used to locate adrenal tumors.
Blood test results showing changes in body chemistry also
may point to Cushing's syndrome. These include:
An increase in the number of white blood cells