Most incidental adrenal tumors are nonfunctioning, regardless of patient age, study finds

About 70% of identified adrenal tumors were nonfunctioning in a community population study conducted in China.

Researchers at a single health examination center in Chongqing performed a cross-sectional study of 25,356 participants receiving annual health assessments between November 2020 and November 2021. On weekdays, the first 100 patients ages 18 to 78 years undergoing health checks were invited to take part in this study and undergo adrenal CT. Those who had adrenal tumors on imaging were further evaluated for malignancy risk and adrenal function. Results were published Sept. 13 by Annals of Internal Medicine.

Among all participants, 351 were identified as having adrenal tumors (1.4%; 95% CI, 1.2% to 1.5%). The rate was higher in men than in women (1.6% [95% CI, 1.3% to 1.8%] vs. 1.2% [95% CI, 1.0% to 1.4%]). The prevalence of adrenal tumors increased with age in both men and women, from 0.2% in adults ages 18 to 25 years to 3.2% in adults older than age 65 years. Of the 351 participants with adrenal tumors, 337 participants were diagnosed with an adrenocortical adenoma and 14 were diagnosed with another benign nodule. No participants were determined to have a malignant mass. The median diameter of the nodules was 15 mm (range, 10 to 45 mm), which the study authors noted is smaller than in many previous studies, leading them to speculate that intentional and careful assessment by radiologists leads to more smaller tumors being detected. Only two tumors had a diameter of 40 mm or greater.

Among 212 patients 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. Proportions of nonfunctioning adenomas were similar in various age groups (72.2%, 67.8%, and 72.2% in those ages <46, 46 to 65, and ≥66 years, respectively). The study authors noted that many patients declined endocrine testing, perhaps because they had initially presented for regular health checkups and usually had no symptoms, while hormonal assessment required them to attend the hospital at least twice for blood draws in a short period of time.

An accompanying editorial noted that patients were more likely to decline hormone testing if they were older and had hypertension. Both mild autonomous cortisol secretion and primary aldosteronism could have been more prevalent in this group, the editorial said. Still, the study provides “important insights into the prevalence of adrenal tumors in an unselected cohort of patients” and the findings “support current recommendations for universal hormonal testing in any patient with an adrenal incidentaloma,” the editorialist wrote.