Cushing’s syndrome diagnosis accuracy highest with urinary free cortisol test

cushings-syndrome-diagnosis-accuracy-highest-with-urinary-free-cortisol-testDiagnosis accuracy of Cushing’s syndrome is highest with urinary cortisol test. A study published in The Journal of Clinical Endocrinology and Metabolism found a 24-hour urinary free cortisol test can most accurately diagnose Cushing’s syndrome.

The researchers analyzed data from 137 adults, all with hypercortisolism, between 2012 and 2014. Thirty-eight of the participants had a confirmed diagnosis of Cushing’s syndrome, and 99 did not. Researchers measured 24-hour urinary free cortisol with liquid chromatography-tandem mass spectrometry (LC-MS/MS), late-night salivary cortisol with a radio-immunometric method, and serum cortisol with a 1-mg dexamethasone suppression test. The three tests were performed on patients within two weeks.


LC-MS/MS test – used to measure 24-hour urinary free cortisol – was found to reveal higher positive ratio and lower likelihood ratio among the three tests.

The researchers wrote, “This result is rather surprising, because some authors have recently advocated replacing [the urinary free cortisol] assay with other tests. Our findings go against such a hypothesis, probably because we used LC-MS/MS in our routine clinical practice for all patients, meaning that high [urinary free cortisol] concentrations pointed to a high likelihood of [Cushing’s syndrome].”

Higher urinary free cortisol was found among men with Cushing’s syndrome, as well as greater cortisol suppression in the 1-mg dexamethasone suppression test in women, but gender did not affect test accuracy.
The researchers concluded, “Choosing between valid tests for ruling out [Cushing’s syndrome] in high-risk populations requires an understanding of their diagnostic performance in different clinical settings. We recommend measuring [urinary free cortisol] with LC-MS/MS as the first-line screening test for the diagnosis of [Cushing’s syndrome], and then confirming hypercortisolism with the 1-mg [dexamethasone suppression test] or late-night salivary cortisol assay.”

Know all about cortisol urine test

A cortisol urine test measures the amount of cortisol in the urine. Cortisol is produced by the adrenal gland and is released into the body during times of stress – physical or emotional. Aside from being the stress hormone, cortisol performs other important functions in the body, like controlling blood sugar, regulating blood pressure, fighting infection, regulating mood, and playing a role in metabolism of carbohydrates, fats, and proteins.

If you are showing symptoms of a medical condition that causes cortisol to fluctuate, your doctor will perform a cortisol urine test to help diagnosis.

Common symptoms for high cortisol include:

  • Frequent urination
  • Increase in thirst
  • Fatty tissue deposits, especially around the abdomen and upper back
  • Pink or purple stretch marks
  • Weight gain
  • Fatigue
  • Muscle weakness
  • Thinning skin that bruises easily

Symptoms of low cortisol are:

  • Weight loss
  • Fatigue
  • Dizziness
  • Fainting
  • Muscle weakness
  • Abdominal pain
  • Diarrhea
  • Constipation

Based on your test results, your doctor will provide you with a diagnosis and be able to begin treatment for whatever the condition may be.

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Author Bio

Mohan Garikiparithi got his degree in medicine from Osmania University (University of Health Sciences). He practiced clinical medicine for over a decade before he shifted his focus to the field of health communications. During his active practice he served as the head of the Dept. of Microbiology in a diagnostic centre in India. On a three-year communications program in Germany, Mohan developed a keen interest in German Medicine (Homoeopathy), and other alternative systems of medicine. He now advocates treating different medical conditions without the use of traditional drugs. An ardent squash player, Mohan believes in the importance of fitness and wellness.