Situations Test preferred Test not preferred Cyclic Cushing's syndrome  UFC or LNSC DST Mild Cushing's syndrome  LNSC or DST UFC Pseudo Cushing's syndrome  LNSC or DST UFC CS patients on antiepileptics  UFC or LNSC DST Adrenal incidentaloma  DST UFC or LNSC Pregnancy  UFC DST, LNSC Severe chronic kidney disease  DST or LNSC UFC Low pretest probability  UFC High pretest probability  LNSC UFC: urinary free cortisol; LNSC: late-night salivary cortisol; DST: dexamethasone suppression test
Discrepancies in results of low-and high-dose dexamethasone suppression tests
for diagnosing preclinical Cushing's syndrome.
In the the 3rd post-operative year, hormonal examination revealed cortisol level under 1.8 pg/dL after low-dose dexamethasone suppression test
(LDDST) and radiological examination showed no adenomatous residue in the pituitary gland except for the former cystic lesion.
Incidentalomas should be evaluated for hormonal change with an overnight 1-mg dexamethasone suppression test
to detect subclinical Cusbing's syndrome.
Low-dose dexamethasone suppression test
(DST), 24-h urinary free cortisol (UFC) levels, highdose DST, corticotropin-releasing hormone (CRH) test and imaging modalities are among the current diagnostic approaches (4).
For patients with masses less than 3 cm, the physician should do a 1-mg dexamethasone suppression test
In a patient of cushingoid appearance, a 24-hour urine cortisol test or low-dose dexamethasone suppression test
Some medical centers recommend the 1-mg overnight dexamethasone suppression test
followed by morning plasma cortisol measurement as the preferred screening test for Cushing syndrome.
To exclude Cushing's syndrome, the dexamethasone suppression test
The two main tests are the low-dose dexamethasone suppression test
(LDDST) and the ACTH stimulation test, but there are several other companion tests that may be recommended including the urine cortisohcreatinine ratio and advanced imaging such as abdominal ultrasound.
Methods used to evaluate adrenal fatigue included salivary cortisol rhythm, direct awakening cortisol, cortisol awakening response, morning serum cortisol, night salivary cortisol, area under curve measurement, dexamethasone suppression test
, dehydroepiandosterone sulfate or DHEA-S, adrenocorticotropic hormone or ACTH, mental stress test, 24-hour urinary free cortisol, cosyntrophin stimulation test, morning area under curve, corticotrophin releasing hormone, total urinary cortisol metabolites and oral glucose tolerance test.
The second test is called a dexamethasone suppression test
. This can be done with low or high doses of dexamethasone and, in some cases, your veterinarian may use both to make a diagnosis.