Prevalence and Characteristics of Adrenal Tumors in an Unselected Screening Population A Cross-Sectional Study

Background: With the widespread use of advanced imaging technology, adrenal tumors are increasingly being identified. Objective: To investigate the prevalence and characteristics of adrenal tumors in an unselected screening population in China. Design: Cross-sectional study. (ClinicalTrials.gov: NCT04682938) Setting: A health examination center in China. Patients: Adults having an annual checkup were invited to be screened for adrenal tumors by adrenal computed tomography. Measurements: The participants with adrenal tumors had further evaluation for malignancy risk and adrenal function. Results: A total of 25356 participants were screened, 351 of whom were found to have adrenal tumors, for a prevalence of 1.4%. The prevalence increased with age, from 0.2% in participants aged 18 to 25 years to 3.2% in those older than 65 years. Among 351 participants with adrenal tumors, 337 were diagnosed with an adrenocortical adenoma, 14 with another benign nodule, and none with a malignant mass. In 212 participants with an adenoma who completed endocrine testing, 69.3% were diagnosed with a nonfunctioning adenoma, 18.9% with cortisol autonomy, 11.8% with primary aldosteronism, and none with pheochromocytoma. Proportions of nonfunctioning adenomas were similarly high in various age groups (72.2%, 67.8%, and 72.2% in those aged <46, 46 to 65, and >= 66 years, respectively). Limitation: Only 212 of 337 participants with an adrenocortical adenoma had endocrine testing. Conclusion: The prevalence of adrenal tumors in the general adult screening population is 1.4%, and most of these tumors are nonfunctioning regardless of patient age. Cortisol and aldosterone secretion are the main causes of functional adenomas.