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Endocrine Abstracts (2022) 81 P10 | DOI: 10.1530/endoabs.81.P10

1Umeå University, Department of Public Health and Clinical Medicine, Umeå, Sweden; 2Umeå University, Department of Medical Biosciences, Umeå, Sweden; 3Linköping University, Department of Clinical Chemistry, and Department of Biomedical and Clinical Sciences, Linköping, Sweden; 4Karolinska University Hospital, Department of Clinical Chemistry, Stockholm, Sweden; 5Karolinska institute, Department of Molecular medicine and surgery, Stockholm, Sweden; 6Karolinska University Hospital, Department of Endocrinology, Stockholm, Sweden; 7Skåne University Hospital, Department of Endocrinology, Malmö, Sweden; 8Uppsala University, Department of Medical Sciences, Endocrinology and Mineral Metabolism, Uppsala, Sweden; 9Uppsala University Hospital, Department of Endocrinology and Diabetes, Uppsala, Sweden; 10Lund University, Department of Clinical Chemistry and Pharmacology, Lund, Sweden; 11University of Gothenburg, Department of Internal Medicine and Clinical Nutrition, Gothenburg, Sweden; 12Sahlgrenska University Hospital, Department of Clinical Chemistry, Gothenburg, Sweden; 13Örebro University, Department of Internal Medicine, School of Health and Medical Sciences, Örebro, Sweden


Background & Objective: Late night salivary cortisol (LNSC) and 1 mg overnight dexamethasone suppression test (DST) are two of the three recommended screening tests for Cushing’s syndrome (CS). The classical DST uses serum cortisol, but analysis of salivary cortisol and cortisone has shown high diagnostic accuracy at DST (1). Salivary cortisol can be analysed with immunoassays, which suffer from variable degree of cross reactivity with other steroids, or with LC-MS/MS, highly specific for cortisol but more time consuming and expensive. For optimal diagnostic accuracy the reference interval and diagnostic cut-off for CS should be determined for each analytical method. We aimed to establish reference intervals and compare diagnostic accuracy for late-night and post-DST salivary cortisol and cortisone analysed with clinical routine methods used in Sweden.

Design & Method: Saliva was collected at 23:00 and after DST at 08:00 in 155 reference subjects and 22 patients with CS. Samples were aliquoted and analysed with three immunoassays for salivary cortisol and three LC-MS/MS methods for salivary cortisol and cortisone. The upper reference limit (URL) was calculated as the 97.5th percentile of the reference population and sensitivity and specificity for CS was calculated. The diagnostic accuracy for each method was compared with our published LC-MS/MS using area under the curves (AUCs) for receiver operating characteristics (ROC) curves (1).

Results: The URL for LNSC with the LC-MS/MS methods were 3.4–3.9 nmol/l, and with the immunoassays; Roche 5.8 nmol/l; Salimetrics 4.3 nmol/l; and Cisbio 21.6 nmol/l. After DST, the URL for salivary cortisol were 0.7–1.0 nmol/l for LC-MS/MS, 2.4 nmol/l (Roche), 4.0 nmol/l (Salimetrics) and 5.4 nmol/l (Cisbio). The URL for salivary cortisone were 13.5 – 16.6 nmol/l in late night samples and 3.0 – 3.5 nmol/l after DST. ROC AUCs for CS diagnosis were high for all tested methods both for late night samples (0.974 – 0.986) and after DST (0.964 – 0.996). For late night samples salivary cortisol (Roche) and salivary cortisone (LC-MS/MS) showed a slightly, but significantly, higher diagnostic accuracy.

Conclusions: We present robust reference limits for salivary cortisol and cortisone in late night samples and after DST for six clinically used methods. Reference limits vary considerably for different methods. However, using method specific cut offs, all methods show high diagnostic accuracy for CS.

Reference

1. Bäcklund N, et al. Reference intervals of salivary cortisol and cortisone and their diagnostic accuracy in Cushing’s syndrome. Eur J Endocrinol. 2020 Jun;182(6):569–582.

Volume 81

European Congress of Endocrinology 2022

Milan, Italy
21 May 2022 - 24 May 2022

European Society of Endocrinology 

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