Neutrophil-Lymphocyte Ratio as an Initial Screening Biomarker for Differential Diagnosis of Cushing's Syndrome from Nonfunctional Adenoma in Patients with an Adrenal Mass

OBJECTIVE: Assessing excess adrenal hormones is important in patients with adrenal mass. Current screening tests for excess cortisol hormones are complex, so it cannot be done sometimes due to the limited medical resources. The aim of the study was to evaluate whether the neutrophil-lymphocyte ratio (NLR) can be used as an initial screening biomarker for Cushing's syndrome (CS) in patients with an adrenal mass. METHODS: This retrospective study included a total of 185 patients with CS and 185 patients with nonfunctional adrenal adenoma (matched 1 : 1 by sex, body mass index, and discharge date). The NLR was compared between the two groups. The association between NLR and serum and urinary cortisol concentrations was analyzed, and an NLR cut-off value for CS screening was calculated. RESULTS: NLR (3.38 (2.33, 5.45) vs. 2.13 (1.74, 3.00), P < 0.001) was significantly higher in the CS group than in the nonfunctional adenoma group. In CS patients, the NLR was positively associated with serum cortisol concentrations at 8 am, with 24-hour urine free cortisol and with serum cortisol after a 1 mg dexamethasone suppression test (P < 0.001 each). An NLR cut-off of 2.2 had a sensitivity of 80.0% and a specificity of 54.05%. The weighted Youden index for the NLR was similar to that of the 24-hour urine free cortisol and late-night serum cortisol tests, which are recommended initial tests for CS diagnosis. CONCLUSION: The NLR may be useful for initial screening for CS among patients with an adrenal mass as an easy and convenient marker.