Objective: To analyze the clinical characteristics and current status of diagnosis and treatment of adrenal incidentaloma (AI). Methods: Clinical data of 488 patients admitted to Peking University First Hospital who met the AI diagnostic criteria from January 2012 to December 2018 were retrospectively analyzed. Results: ① Of the 488 AI patients

326 cases (66.80%) were found during physical examination

409 cases (83.81%) were non-functional lesion. ② There were 180 cases received surgical treatment

among which 27 patients (15.00%) were pathologically diagnosed as pheochromocytoma. The area under curve of blood normetane-phrine (NMN) in the diagnosis of pheochromocytoma was 0.906

with the sensitivity of 92.9%

the specificity of 81.6%

and the Youden’s index of 0.745. The area under curve of the joint test by computed tomography (CT)

blood norepinephrine (NE) and urine NE was 0.828

with the sensitivity of 77.8%

the specificity of 85.3%

and the Youden’s index of 0.631. ③ To evaluate the diagnostic value of overnight 1 mg dexamethasone inhibition test for subclinical Cushing’s syndrome (SCS)

the area under curve of the 1 mg overnight dexamethasone inhibition test in diagnosis of SCS was 0.967

the optimal cut-off point was 2.1 μg/dL

with the sensitivity of 93.3%

the specificity of 92.4%

and the Youden’s index of 0.857. ④ A total of 65 patients of non-functional AI were followed up for 6 months to 7 years

and only 2 cases progressed to SCS. ⑤ There were 31 additional cases of adrenal mass<1 cm

and only 2 cases (6.45%) were primary aldosteronism. Conclusion: ① Two thirds of AI was found by routine physical examination

which was the main reason for the increase of incidence of accidental tumor

and 84% of which was non-functional lesions. ② The value of CT combined with blood NE and urine NE in the diagnosis of pheochromocytoma is lower than that of blood NMN. ③ The optimal cut-off point for the 1 mg overnight dexamethasone inhibition test diagnosis of SCS is 2.1 μg/dL

which is better than 1.8 μg/dL. ④ Non-functional AI may progress to SCS. ⑤ The clinical significance of adrenal lesions<1 cm function evaluation is unlikely to require

while imaging follow-up may be only required.