Many people on the message boards have had personal experience with a lot of the different types of tests. You can read what they have to say, or ask questions of your own on the Tests Forum

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There's a message board for Cyclical Cushing's that may help you get more insight into this very baffling disease. you can find that board here: Cyclical (Episodic, Intermittent) Cushing's

Best of luck to you!

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Tests such as a computed tomography (CT) or magnetic resonance imaging (MRI) scan can help locate the pheochromocytoma. A test using injected radioactive chemicals that tend to accumulate in pheochromocytomas is also useful. A scan is then performed to see where the radioactive chemicals are.

More about Pheochromocytoma
   This Topic on the Message Boards.

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From GH Deficiency

This information was developed by David Cook, M.D. It is not intended to substitute for a full and frank consultation with qualified medical personnel, which is the primary means for a patient to obtain care and treatment. The information was believed to be current on November 5, 1998 and with the lapse of time, certain of this material will be outdated.

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Physicians have always relied upon analysis of urine specimens in order to diagnosis and treat many disease processes. Twenty-four hour urine collections are often employed to estimate the production rates of various hormones. The accuracy of test results depends entirely on the accuracy of the urine collection technique. These instructions are provided as a guide to ensure that your 24-hour urine collection is obtained in a manner that will permit reliance upon the test results.

You should collect every drop of your urine produced during a 24-hour period. You should begin the collection in the morning or else at a time specified by your physician. At that time, pass your urine, flush it down the toilet, and note the exact time. These measures permit you to start with an empty bladder and an empty collection bottle. Thereafter, collect every single drop of urine during the day and following night. The very next morning, exactly 24 hours from the start time, you should empty your bladder and add that urine to the collection bottle. This will complete the collection. There should be no more than a 5 or 10 minute variation between the start and stop time. If you find that you must urinate an hour or so before the appointed time, go ahead and do so, then drink a full glass of water so that you could urinate again at the time to end the collection.

Urine samples should be collected in a large cup or other container and then poured into the large bottle. Do not try to urinate directly into the bottle. Void urine prior to bowel movements in order to avoid losing urine that might normally be passed during a bowel movement.

Some patients are asked to collect more than one consecutive 24-hour urine sample. If that is the case, you should complete the first collection as instructed. Then, begin the second collection by adding any urine made in the next 24-hours to the second bottle. You should not discard any urine when starting the second or any subsequent collections. Simply change bottles at the stop and start times after adding that last sample required to complete the previous collection.

The bottles for some tests contain a weak acid as a preservative. Do not discard the acid. If you accidentally get acid or urine from the bottle on your skin or clothing, rinse the effected area immediately with plenty of cold water. Collection bottles must be refrigerated. This is best accomplished by using an ice chest, cooler, or if so inclined, your refrigerator.

If you forget to collect all of the urine or perform the test improperly, discard the specimen and start again on another day. If the bottle contained an acid preservative, you will need to obtain a new bottle from the laboratory or your physician's office. Otherwise, you may reuse the bottle after rinsing it with distilled water.

Finally, please remember to call your physician or nurse if you have any questions about the proper collection of a 24-hour urine sample.

More information on Urine Testing is available by clicking here.

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Because Cushing's Syndrome is a rare but serious disorder, it is very important to carefully exclude (rule out) other disorders and then separate the different types, leading eventually to a specific cause that can be treated. This process of testing and excluding usually takes days to weeks and requires a lot of patience and cooperation by the person being tested.

After the initial history, physical exam and routine blood tests, the first step is to prove cortisol excess with specific blood and 24 hour urine tests for cortisol. Inappropriate cortisol production will then be evaluated by doing a dexamethasone suppression test. Dexamethasone (steroid) pills are given by mouth, then blood and urine are collected for cortisol and other adrenal hormones. A screening test might be done initially with an overnight test, but if it is abnormal, usually a 4 day test divided into low and high dose dexamethasone is needed. To separate ACTH dependent from independent types, a blood test for ACTH in the morning is done. Blood and urine tests for adrenal androgens are useful. Testing with other drugs, such as metyrapone and CRH (corticotropin releasing hormone) may also be needed.

Once all of the blood and urine results are analyzed, they will establish whether some type of Cushing's Syndrome is present, and should indicate whether the disease is ACTH dependent (pituitary or ectopic) or independent (an adrenal tumor). Localizing techniques such as CT or MRI are then used to find the tumor. Often a pituitary tumor is tiny and hard to find, so a special test of the release of ACTH from both sides of the pituitary (petrosal sinus sampling) might be needed. Small tumors producing ectopic ACTH are also sometimes difficult to localize and require repeated scans and x-rays.

Written by: Paul Margulies, M.D., F.A.C.P., F.A.C.E. Medical Director of NADF Clinical Associate Professor of Medicine, Cornell University Medical College and posted at http://www.medhelp.org/www/nadf4.htm

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24-Hour Urinary Free Cortisol Level This is the most specific diagnostic test. The patient's urine is collected over a 24-hour period and tested for the amount of cortisol. Levels higher than 50-100 micrograms a day for an adult suggest Cushing's syndrome. The normal upper limit varies in different laboratories, depending on which measurement technique is used.

Once Cushing's syndrome has been diagnosed, other tests are used to find the exact location of the abnormality that leads to excess cortisol production. The choice of test depends, in part, on the preference of the endocrinologist or the center where the test is performed.

Dexamethasone Suppression Test This test helps to distinguish patients with excess production of ACTH due to pituitary adenomas from those with ectopic ACTH-producing tumors. Patients are given dexamethasone, a synthetic glucocorticoid, by mouth every 6 hours for 4 days. For the first 2 days, low doses of dexamethasone are given, and for the last 2 days, higher doses are given. Twenty-four hour urine collections are made before dexamethasone is administered and on each day of the test. Since cortisol and other glucocorticoids signal the pituitary to lower secretion of ACTH, the normal response after taking dexamethasone is a drop in blood and urine cortisol levels. Different responses of cortisol to dexamethasone are obtained depending on whether the cause of Cushing's syndrome is a pituitary adenoma or an ectopic ACTH-producing tumor.

The dexamethasone suppression test can produce false-positive results in patients with depression, alcohol abuse, high estrogen levels, acute illness, and stress. Conversely, drugs such as phenytoin and phenobarbital may cause false-negative results in response to dexamethasone suppression. For this reason, patients are usually advised by their physicians to stop taking these drugs at least one week before the test.

CRH Stimulation Test This test helps to distinguish between patients with pituitary adenomas and those with ectopic ACTH syndrome or cortisol-secreting adrenal tumors. Patients are given an injection of CRH, the corticotropin-releasing hormone which causes the pituitary to secrete ACTH. Patients with pituitary adenomas usually experience a rise in blood levels of ACTH and cortisol. This response is rarely seen in patients with ectopic ACTH syndrome and practically never in patients with cortisol-secreting adrenal tumors.

Direct Visualization of the Endocrine Glands (Radiologic Imaging) Imaging tests reveal the size and shape of the pituitary and adrenal glands and help determine if a tumor is present. The most common are the CT (computerized tomography) scan and MRI (magnetic resonance imaging). A CT scan produces a series of x-ray pictures giving a cross-sectional image of a body part. MRI also produces images of the internal organs of the body but without exposing the patient to ionizing radiation.

Imaging procedures are used to find a tumor after a diagnosis has been established. Imaging is not used to make the diagnosis of Cushing's syndrome because benign tumors, sometimes called "incidentalomas", are commonly found in the pituitary and adrenal glands. These tumors do not produce hormones detrimental to health and are not removed unless blood tests show they are a cause of symptoms or they are unusually large. Conversely, pituitary tumors are not detected by imaging in almost 50 percent of patients who ultimately require pituitary surgery for Cushing's syndrome.

Petrosal Sinus Sampling This test is not always required, but in many cases, it is the best way to separate pituitary from ectopic causes of Cushing's syndrome. Samples of blood are drawn from the petrosal sinuses, veins which drain the pituitary, by introducing catheters through a vein in the upper thigh/groin region, with local anesthesia and mild sedation. X-rays are used to confirm the correct position of the catheters. Often CRH, the hormone which causes the pituitary to secrete ACTH, is given during this test to improve diagnostic accuracy. Levels of ACTH in the petrosal sinuses are measured and compared with ACTH levels in a forearm vein. ACTH levels higher in the petrosal sinuses than in the forearm vein indicate the presence of a pituitary adenoma; similar levels suggest ectopic ACTH syndrome.

The Dexamethasone-CRH Test Some individuals have high cortisol levels, but do not develop the progressive effects of Cushing's syndrome, such as muscle weakness, fractures and thinning of the skin. These individuals may have Pseudo Cushing's syndrome, which was originally described in people who were depressed or drank excess alcohol, but is now known to be more common. Pseudo Cushing's does not have the same long-term effects on health as Cushing's syndrome and does not require treatment directed at the endocrine glands. Although observation over months to years will distinguish Pseudo Cushing's from Cushing's, the dexamethasone-CRH test was developed to distinguish between the conditions rapidly, so that Cushing's patients can receive prompt treatment. This test combines the dexamethasone suppression and the CRH stimulation tests. Elevations of cortisol during this test suggest Cushing's syndrome.

Some patients may have sustained high cortisol levels without the effects of Cushing's syndrome. These high cortisol levels may be compensating for the body's resistance to cortisol's effects. This rare syndrome of cortisol resistance is a genetic condition that causes hypertension and chronic androgen excess.

Sometimes other conditions may be associated with many of the symptoms of Cushing's syndrome. These include polycystic ovarian syndrome (PCOS), which may cause menstrual disturbances, weight gain from adolescence, excess hair growth and sometimes impaired insulin action and diabetes. Commonly, weight gain, high blood pressure and abnormal levels of cholesterol and triglycerides in the blood are associated with resistance to insulin action and diabetes; this has been described as the "Metabolic Syndrome-X." Patients with these disorders do not have abnormally elevated cortisol levels.

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This test relies on the fact that if the source of your high ACTH is the pituitary gland blood levels taken from very near the gland will be higher than the blood level in an arm vein. Pituitary gland tumors are often tiny and can't be seen even with the most modern scanners. This test will help your endocrinologist to know with almost 100% certainty whether the pituitary gland is the source or if a search is needed elsewhere (for example in the lungs or abdomen). This guides treatment, for example the recommendation for Pituitary surgery.

For more information on the PSS, as it is often referred to, see Petrosal Sinus Sampling

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The Magnetic Stereotaxis System (MSS), developed by a team of American neurosurgeons, is touted as a safer, less invasive and more effective way to biopsy brain tumors. Other applications may include diagnosing and treating cardiovascular conditions, such as coronary artery disease, cardiac arrhythmia and aneurysms.

For more information about MSS, see The Magnetic Stereotaxis System (MSS)

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