Diagnostic performance of a newly developed salivary cortisol and cortisone measurement using an LC–MS/MS method with simple and rapid sample preparation
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Late-night salivary cortisol level is one of the first-line tests recommended by the Endocrine Society for the diagnosis of endogenous hypercortisolism. Most routine laboratories measure cortisol levels using immunoassay tests which fail to determine low cortisol levels accurately due to the numerous interfering substances. A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method with simple and rapid sample preparation was developed for the simultaneous measurement of cortisol and cortisone and its performance in the diagnosis of endogenous hypercortisolism was evaluated.
324 late-night saliva samples were analyzed from which 272 samples were derived from patients with a suspected diagnosis of endogenous hypercortisolism. Salivary cortisol levels were assayed using an electrochemiluminescent immunoassay (ECLIA, Cortisol II, Roche), and simultaneous measurement of cortisol and cortisone was performed using an LC–MS/MS method.
A strong correlation between cortisol results measured using ECLIA and LC–MS/MS (r 2 = 0.892) was demonstrated. Receiver operating characteristics (ROC) analysis showed good diagnostic performance of cortisol and cortisone levels assayed using LC–MS/MS method and for cortisol measured using ECLIA.
Late-night salivary cortisol and cortisone are useful parameters for the diagnosis of hypercortisolism. Using samples obtained from patients where the diagnosis of hypercortisolism is extremely challenging cut-off values for midnight salivary cortisol and cortisone measured by LC–MS/MS method were established.
KeywordsLC–MS/MS ECLIA Hypercortisolism Late-night saliva Cortisol Cortisone
Liquid chromatography–tandem mass spectrometry
Receiver operating characteristics
Late-night salivary cortisol
Urine free cortisol
Cortisol binding globulin
Multiple reaction monitoring
Cell exit potential
Areas under curve
The authors receive financial support from Hungarian Academy of Sciences “Lendulet 2013” Grant (AP) and Bionics Innovation Center (AP, KR, GK). The authors are grateful to Professor Barna Vasarhelyi (Department of Laboratory Medicine, Semmelweis University) for useful comments and critical review of the manuscript.
Study design: AP, KM, MT, KR; performing LC–MS/MS measurements: KM, GK, ZM, BM; evaluation of results: AP, KM, GK; clinical evaluation of patients: MT, KR, NS, JT; writing the manuscript: KM, AP; all authors reviewed and agreed with the submission of manuscript.
Compliance with ethical standards
Conflict of interest
The authors have no conflicts of interest to declare.
The study protocol was approved by the National Scientific and Ethical Committee, Medical Research Council of Hungary (TUKEB, ETT), and was executed according to the Declaration of Helsinki principles.
Informed consent was obtained from all patients involved in the study.
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