Endocrine Abstracts

JOINT3989

Introduction: Incidentally discovered adrenal nodules are detected in 1–7% of abdominal imaging studies. The 2023 ESE guidelines recommend the 1-mg overnight dexamethasone suppression test (ODST) for screening autonomous cortisol secretion (ACS). Previous studies suggest 20–50% of adrenal nodules patients will fail an ODST which, in the absence of clinical evidence of Cushing’s syndrome (CS), is termed mild autonomous cortisol secretion (MACS). Herein, we report findings from a large cohort of patients with adrenal nodules.

Methods: 512 patients (239 males, 273 females) referred between 2019 and 2023 were included. Patients with a positive ODST (cortisol ≥50 nmol/l) had dexamethasone level measured on the same sample to rule out false positives (defined as dexamethasone ≤3.7 nmol/l). Patients with abnormal ODST and dexamethasone levels >3.7 nmol/l were investigated for additional evidence of ACS defined as at least two of the following: elevated 24-hour urinary free cortisol, elevated late-night salivary cortisol, 0900 h plasma ACTH <10 pg/mL, suppressed DHEAS level.

Results: Of 512 patients, 52 were excluded due to incomplete data, leaving 460 participants. ODST was normal in 292 (63.5%) and abnormal in 168 (36.5%). Among the abnormal ODST group, 18/168 false positives were identified through dexamethasone measurement, while 150/168 with adequate dexamethasone levels were referred to the specialist adrenal multidisciplinary team (MDT) for further evaluation. Of the 150 patients, 40/150 were not recommended for further investigation by the MDT, and 14/150 declined additional assessment. Among the remaining 96 patients, 65 had no further clinical or biochemical evidence of ACS, while 31 had findings suggestive of ACS, including 3 with overt Cushing’s syndrome (CS). The median cortisol level in patients with additional positive biochemical evidence of ACS was significantly higher at 102 nmol/l compared to 79 nmol/l in the abnormal ODST-only group who had no other clinical or biochemical evidence of ACS (P=0.0019).

Conclusion: This study highlights the need to consider new biomarkers to better detect MACS and stratify those at highest cardiovascular risk. Furthermore, a revision of the current ODST cortisol cut-off with further analysis needed to improve diagnostic accuracy and evaluate the clinical and economic impact of MACS screening.