Abstract Objectives Salivary cortisol and cortisone at late night and after dexamethasone suppression test (DST) are increasingly used for screening of Cushing’s syndrome (CS). We aimed to establish reference intervals for salivary cortisol and cortisone with three liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques and for salivary cortisol with three immunoassays (IAs), and evaluate their diagnostic accuracy for CS. Methods Salivary samples at 08:00 h, 23:00 h and 08:00 h after a 1-mg DST were collected from a reference population (n=155) and patients with CS (n=22). Sample aliquots were analyzed by three LC-MS/MS and three IA methods. After establishing reference intervals, the upper reference limit (URL) for each method was used to calculate sensitivity and specificity for CS. Diagnostic accuracy was evaluated by comparing ROC curves. Results URLs for salivary cortisol at 23:00 h were similar for the LC-MS/MS methods (3.4–3.9 nmol/L), but varied between IAs: Roche (5.8 nmol/L), Salimetrics (4.3 nmol/L), Cisbio (21.6 nmol/L). Corresponding URLs after DST were 0.7–1.0, and 2.4, 4.0 and 5.4 nmol/L, respectively. Salivary cortisone URLs were 13.5–16.6 nmol/L at 23:00 h and 3.0–3.5 nmol/L at 08:00 h after DST. All methods had ROC AUCs ≥0.96. Conclusions We present robust reference intervals for salivary cortisol and cortisone at 08:00 h, 23:00 h and 08:00 h after DST for several clinically used methods. The similarities between LC-MS/MS methods allows for direct comparison of absolute values. Diagnostic accuracy for CS was high for all salivary cortisol and cortisone LC-MS/MS methods and salivary cortisol IAs evaluated.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

OBJECTIVE:The challenge of finding patients with the rare conditon of diabetes insipidus in need of vasopressin treatment is demanding. The guidelines for performing the fluid deprivation test and interpreting the results are abundant. We evaluated the discriminative capacity of the fluid deprivation test in patients with polyuria to define a cut off for a more effective discrimination between diabetes insipidus and other polyuria syndromes. RESEARCH DESIGN AND METHODS:Retrospective review and data collection of all ambulatory fluid deprivation tests, of patients with mild polyuria and polydipsia (< 3 L/day), performed between 2000 and 2018. Serum osmolality, urine osmolality, urine volumes and clinical information of diagnosis were retrieved from the patient's medical records. RESULTS:The study group consisted of 153 patients, 123 were diagnosed with non-diabetes insipidus and 30 with diabetes insipidus. After 12 h fasting (baseline) median duration of the fluid deprivation test was 5 h (fasting range: 12-21 h). At baseline, there was a significant difference between median serum and urine osmolality between the groups (P < 0.05). The best cut-off for the diagnosis of diabetes insipidus, was the combination of < 400 mosmol/kg in urine and > 302 mosmol/kg in serum. With this cut-off a sensitivity of 90% and specificity of 98% was achieved. CONCLUSION:After 12 h fasting our proposed cut off clearly differentiated between diabetes insipidus, and non-diabetes insipidus suggesting a possibility to considerably reduce the duration of the fluid deprivation test.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)