OPTIMIZING DIAGNOSTIC ACCURACY IN CUSHING SYNDROME USING 1 MG DEXAMETHASONE SUPPRESSION TEST CUT-OFFS.

Introduction: Diagnosing Cushing Syndrome (CS) remains challenging due to its diverse symptoms and the complexity of its subtypes. This study aimed to optimize diagnostic cut-off values for differentiating CS subtypes using the 1 mg dexamethasone suppression test (DST) in a cohort of 237 patients. Materials and Methods: Retrospective data from patients diagnosed with non-functional adrenal adenomas (NFA), mild autonomous cortisol secretion (MACS), adrenal CS, and pituitary CS at the Dokuz Eylül University Endocrinology and Metabolism Clinic (2005-2016) were analyzed. Sensitivity and specificity of morning cortisol levels after DST were evaluated using receiver operating characteristic (ROC) curve analysis. Results: The analysis identified optimal morning cortisol cut-off levels: 2.14 μg/dL (59.04 nmol/L) for MACS, 2.3 μg/dL (63.4 nmol/L) for adrenal CS, and 2.33 μg/dL (64.28 nmol/L) for pituitary CS. Conclusion: These optimized thresholds demonstrated high sensitivity and specificity, significantly improving diagnostic precision over the conventional threshold of 1.8 μg/dL (50 nmol/L). The findings underscore the importance of tailored cut-off values to address subtype-specific diagnostic challenges, reducing delays and mitigating long-term complications. Personalized diagnostic approaches, incorporating patient demographics and disease-specific characteristics, are essential for enhancing diagnostic accuracy and facilitating timely interventions.