1. The prevalence of adrenal tumors in the general adult screening population is 1.4%.

2. The majority of these adrenal tumors are nonfunctioning regardless of patient age.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Adrenal incidentalomas are incidentally found nodules, usually at least one centimeter in diameter, found in patients without apparent clinical signs of adrenal diseases. A recent study has shown that the incidence of these adrenal tumors has increased 10-fold in the past 20 years. This is largely due to the development and widespread use of advanced imaging technology. However, there is a gap in knowledge as to the epidemiologic data on the prevalence of adrenal tumors, frequency of malignant adrenal tumors, and rates of hormone excess in unselected community populations that do not have prior indications for abdominal imaging. Overall, this study found that the prevalence of adrenal tumors in a large population of persons undergoing routine health checks in China was 1.4%. This study was limited by factors such as participants being part of a homogenous Chinese population, as well as adenomas being diagnosed on the basis of unenhanced computed tomography (CT), which can lead to cysts being misdiagnosed as adenomas. Nevertheless, these study’s findings are significant, as they demonstrate that the prevalence of adrenal tumors in the adult population can be estimated to be 1.4%, with nonfunctioning adenomas accounting for most of the adrenal tumors regardless of age.

Click to read the study in AIM

Relevant Reading: Adrenal Incidentalomas: Insights Into Prevalence

In-Depth [cross-sectional study]: This cross-sectional study was conducted at the community health examination center of the First Affiliated hospital of Chongqing Medical University in China. Patients who were undergoing health checks at this community health center were eligible for the study and to have adrenal imaging (n=25,356). Patients who had known adrenal diseases, continuous use of steroids or drug treatment, or refusal to participate in the study were excluded from the study. The primary outcome was the presence of adrenal tumors assessed via unenhanced CT scans of the adrenal glands, with secondary outcomes including functional assessment of the adrenal tumors. Outcomes in the primary analysis were assessed via generalized linear models and adjusted for sex, age, and body mass index. Based on the primary analysis, among the total participants screened, 1.4% of the participants were found to have adrenal tumors. The prevalence increased with age, from 0.2% in participants ages 18-25 to 3.2% in participants older than age 65. In the 212 participants who completed endocrine testing, 69.3% were diagnosed with a nonfunctioning adenoma, 18.9% were diagnosed with cortisol autonomy, 11.8% were diagnosed with primary aldosteronism, and none were diagnosed with pheochromocytoma. The proportion of nonfunctioning adenomas were similar across various age groups. Overall, this study demonstrates that the prevalence of adrenal tumors in the general adult screening population is 1.4%, with most of these incidentally found tumors classified as nonfunctioning regardless of patient age.

Image: PD

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