Research progress in the detection of urinary cortisol and salivary cortisol by tandem mass spectrometry in the diagnosis of Cushing′s syndrome

Urinary free cortisol (UFC) and mid-night salivary cortisol (MSC) are important indicators for the diagnosis of Cushing′s syndrome (CS) and its efficacy monitoring. The measurement of steroid hormones by tandem mass spectrometry becomes more and more common nowadays worldwide because of its good sensitivity and specificity. Understanding the advantages and disadvantages of liquid chromatography-tandem mass spectrometry (LC-MS/MS) is of great significance for the diagnosis of CS. According to relevant literatures, LC-MS/MS was used by several famous laboratories to detect the range of UFC and MSC in healthy people. In recent years, some literatures have also reported the cut-off value of UFC and MSC detected by LC-MS/MS for the diagnosis of CS. It is generally believed that the cut-off value of UFC detected by LC-MS/MS is 170 nmol/24 h. In future, the determination of glucocorticoid metabolomics by tandem mass spectrometry is expected to provide more comprehensive and predictive information for the individualized diagnosis and treatment evaluation of metabolic syndrome or CS. Key words: Cushing′s syndrome; Liquid chromatography-tandem mass spectrometry; Urinary cortisol; Salivary cortisol; Diagnostic cut-off values