MON-165 Utility of Salivary Cortisol After 1 Mg Oral Dexamethasone in the Evaluation of Incidental Adrenal Tumors

The subclinical Cushing′s syndrome (SCS) is found in 20% of incidental adrenal tumors (AI). The overnight 1 mg oral dexamethasone suppression test (DST) with the measurement of circulating cortisol (F) is a sensitive method to rule out SCS. The assessment of salivary cortisol (SAF) as a surrogate of F became a non-invasive methodological advance. There are few data on the functional evaluation of AI through SAF in DST (SAF(dex)). The aim of this retrospective study was to investigate the utility of SAF(dex) for the detection of SCS in patients with AI. Subjects and Methods: 20 subjects with AI (7 male and 13 women; 65.0 ± 11.0 y/o; BMI: 26.5 ± 1.4) were studied. Sixteen had unilateral and 4 bilateral tumors (size: 10.0 - 90.0 mm; density (UH) was <10.0 in 17 cases and ≥ 10.0 in 3). They were not on drugs that may affect the HPA axis. Eight patients (1 male and 7 women; 20.0–60.0 y/o; BMI: 27.0 ± 3.0) with overt non ACTH dependent Cushing Syndrome (CS) were included as the reference group of active hypercortisolism. CS had unilateral adrenal tumors in 6 cases and bilateral in 2 (size: 11.0 -200.0 mm; density (UH) <10.0: n= 7 and >10.0: n=1).All subjects collected 24-hour urine for urinary free cortisol (UFC). After the urine collection, they obtained whole saliva samples at 23 h for cortisol (SAF(23)). Subsequently, they received 1 mg oral dexamethasone. The following day at 8 h, simultaneous blood (F(dex)) and saliva (SAF(dex)) samples were obtained. F, SAF and UFC were determined by RIA and ACTH by IRMA. Reference values ​​from our laboratory (n= 100): UFC ≤90.0 µg / 24hs; ACTH: 10.0–50.0 pg / ml, SAF(23): 0.5–3.8 nM / l; SAF(dex): 0.5–2.0 nM; F(dex): 13.8–50.0 nM. Statistics were performed by Mann-Whitney and Spearman tests, p <0.05 was considered significant. In AI: ACTH 22.0 ± 11.0 pg /ml; UF:C 47.0 ± 20.0 µg / 24hs; SAF(23:) 1.5 ± 0.9 nM); SAF(dex:) 1.0 ± 0.5 nM and F(dex:) 35.6 ± 10.0 nM were normal and significantly different from CS: 5.6±1.8 pg /ml; 391.0 ± 406.0 µg / 24hs; 20.0 ± 32.0 nM; 27.0 ± 24.0 nM and 674.0 ± 339.0 nM, respectively; p <0.05 in all cases. A positive and significant correlation was demonstrated between SAF(dex) and F(dex) in AI (r = 0.830) and CS (r = 0.905); p <0.05 in both. Interestingly, a woman with overt CS and moderate signs of hypercortisolism, had normal SAF(23) (1.5 nM) and UFC (76.0 µg / 24hs), while SAF(dex) (3.0 nM) and F(dex) (69.0 nM) showed absence of suppression. Surgical resection of the adrenal tumor (an adrenocortical adenoma) and postoperative hypocorticism confirmed the diagnosis of CS. Conclusion: SCS was excluded in all AI. The dexamethasone suppression test using saliva as a diagnostic fluid was a sensitive and practical method to rule out hypercortisolism in these patients.