Table 2. Considerations regarding mass spectrometry measurements for Cushing's syndrome (CS) evaluation.

Advantage provided by mass spectrometry	References
Cortisol measurement results are more specific. In contrast to immunoassays, only true cortisol is measured.	[6,14,25,26,27,28,29,48,56,60,61,73,85]
The variability of cortisol measurements across laboratories is reduced.	[2,25,45,71,73]
Clinical value for the screening of CS is high. Comparable (but probably not better) to many immunoassays.	[2,26,32,61]
May be used to reduce false-positive results obtained through immunoassays.	[2,26,57]
Allows the detection of individually exogenous corticosteroids.	[3,36,37,38]
Ensures adequate plasma dexamethasone levels during DST in equivocal cases.	[6,69,70]
Allows accurate cortisol measurement in patients undergoing interfering medical treatment.	[72]
Allows measurement of endogenous metabolites that may be useful for the following purposes:	[3,39,40]
- subtyping CS	[75]
- classifying adrenal incidentalomes	[42]
- detecting subclinical CS	[74]
- differentiating Cushing's disease from ectopic ACTH syndrome	[43]
- detection of saliva contamination	[62,63]

Abbreviations: ACTH, adrenocorticotropic hormone; CS, Cushing's syndrome; DST, dexamethasone suppression test.