MON-LB078 Desmopressin Stimulated Salivary Cortisol as a Suplementary Tool in the Diagnosis of Cushing's Syndrome

The classic desmopressin test consists of serum cortisol and plasma ACTH measurements after intravenous administration of desmopressin. This test has been shown to have good accuracy in the context of exclusion of Cushing's syndrome in patients with non-tumoral hypercortisolism; with an equal or greater precision than the synthetic corticotrophin-releasing hormone (CRH) test. Meanwhile, salivary cortisol samples are independent of fluctuations in the serum transcortin, reflect the plasma free fraction (about 70%), and are not influenced by the alteration of salivary flow ; It has been largely employed in the evaluation of hypercortisolism states, however its role in the desmopressin test has not been fully evaluated. Aim: To compare salivary cortisol measurements during the desmopressin test in active Cushing’s disease as opposed to obese patients without clinical or biochemical evidence of hypercortisolism. Methods: Nineteen individuals, from endocrine outpatient clinics of an university were enrolled: 11 patients with active Cushing's disease and 8 obese individuals (BMI greater than 35kg / m2). Salivary cortisol plasma ACTH and serum cortisol were collected at baseline, 15, 30, 45, 60 and 120 minutes after IV administration of desmopressin (10 mcg). Salivary cortisol and plasma ACTH were performed by an electrochemiluminescence immunoassay, while serum cortisol was made by competitive immunoassay using direct chemiluminescence. Results: The groups were epidemiologic and clinical homogenous. In comparison to baseline, plasma ACTH, serum and salivary cortisol after desmopressin stimulation were significantly elevated at 45 (P<0,01) and 60 minutes (P<0,01) . The increment in salivary cortisol at 15 (P<0,01) and 30 minutes (P<0,01) was significantly different in patients with Cushing`s disease in comparison to obese patients. Salivary cortisol increased in comparison to baseline in patients with Cushing’s disease (range: 66 to 309%) mainly at 60 minutes, declining thereafter. A positive correlation between salivary and serum cortisol at 30, 45, 60,and 120 minutes was observed in patients with Cushing’s disease, particularly at 120 minutes (rho 0,90, p<0,01). In obese patients, salivary cortisol did not respond to desmopressin administration and there was no correlation between serum and salivary cortisol. Conclusion: Inclusion of the measurement of salivary cortisol to the desmopresin test may add value to its interpretation, combined with serum cortisol and plasma ACTH. Desmopressin stimulated salivary cortisol at 60 minutes could be used as an additional tool in differentiating Cushing`s disease from of non-tumoral hypercortisolism . Further studies in larger and more a diverse populations are needed to confirm the role of desmopressin -stimulated cortisol in the diagnosis of Cushing`s syndrome. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.