Diagnosing Cushing’s Syndrome

by on September 1st, 2014
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Cushing’s Syndrome, also known as hypercortisolism, is a hormone disorder that is caused by elevated levels of cortisol. Those at risk for the syndrome include those aged 20 to 50, obesity, type 2 diabetes, and those with high blood pressure. It is a rare condition.

Signs of Cushing’s

According to the National Institute of Diabetes and Digestive and Kidney Disease, symptoms of Cushing’s Syndrome are a round face, increase in neck fat, thin arms and legs, skin that bruises easily, poor healing, weakened bones, and excess hair grown in the face and neck for women. Men may have erectile dysfunction and loss of sexual desire. More common signs are fatigue, increase in blood pressure and glucose, increase in thirst and urination, muscle weakness, depression, a shoulder hump, anxiety, and irritability.


There is not a single test to diagnose Cushing’s syndrome, but multiple. Three are more common to use for testing than others. These include the 24 hour urinary-free cortisol test, low dose dexamethasone suppression test, and the dexamethasone-corticotrophin-releasing hormone test.

24 Hour Urinary-Free Cortisol

This test measuring the urine for cortisol. Several urine samples are done during a 24 hour period for testing. While the normal limits vary from lab to lab, levels over 50 to 100 micrograms will indicate Cushing’s syndrome in adults.

Low Dose Dexamethasone Suppression

Also known as just LDDST, the patient is given a synthetic glucocorticoid or low dose of dexamethasone. This is given over a two day period, every six hours. There is a urine test prior to the first dose and periodically throughout both days. There is an alternate test that just uses an overnight dose a single time. Either of these tests can give the doctor a positive/negative diagnosis.

Dexamethasone-Corticotrophin-Releasing Hormone Test

Also known as just CRH, there may be an excess of cortisol without showing signs of Cushing’s that this test will test for. This condition, known as pseudo-Cushing’s, does not require treatment for the endocrine glands. This test will be able to tell the difference between the real Cushing’s syndrome and pseudo-Cushing’s. A dose of dexamethasone can prevent those with pseudo-Cushing’s from getting a high cortisol rating with this test while it has no effect on those with actual Cushing’s.


Treatment includes surgery, chemotherapy, radiation, or cortisol-inhibitor drugs. There can be a positive Cushing’s test if the patient is on long term use of glucocorticoids. In this case they can taper off the dosage to the best drug dose for control.


National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH Publication No. 08-3007, July 2008

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