About 1.4% of the general adult population has an adrenal tumor, of which about two thirds are nonfunctioning adenomas regardless of age, a new study suggests.
The detection rate of adrenal incidentaloma, or an incidentally found nodule not causing clinical symptoms, has increased as screening techniques have improved and become more common. However, most published literature on the prevalence of adrenal incidentalomas consists of retrospective surveys based on radiographic diagnosis in a medical record system, which might under- or overestimate the prevalence.
A third of the patients discovered to have such tumors were found to have a previously unsuspected hormonal excess, all patients with an adrenal incidentaloma should get hormone tests, says an editorialist.
The current study design was unique in that participants were recruited from the community rather than hospitalized patients or radiologic series, thereby minimizing selection bias, according to authors Ying Jing, MD, of The First Affiliated Hospital of Chongqing Medical University, China, and colleagues. The findings were published online September 2022 in Annals of Internal Medicine, along with the editorial. The study took place in the community health examination center at the first affiliated hospital of Chongqing Medical University, one of the largest hospitals in southwest China.
In an accompanying editorial, Irina Bancos, MD, writes: “Jing and colleagues provide important insights into the prevalence of adrenal tumors in an unselected cohort of patients.”
The findings “support current recommendations for universal hormonal testing in any patient with an adrenal incidentaloma,” adds Bancos, an adrenal endocrinologist at the Mayo Clinic in Rochester, Minnesota.
Overall, Bancos says that estimates from the study have the advantage of large sample size and minimal imaging bias because participants did not have a clinical indication that required an abdominal CT scan. In addition, Jing and colleagues used a stringent method of CT review by two independent radiologists with a subsequent discussion of any discordant findings. Although this approach is difficult to replicate in clinical practice, it does increase the confidence around determined prevalence estimates.
No Adrenal Malignancies Found in More Than 25,000 Unselected Adults.
Adults who were having an annual check-up were invited to be screened for adrenal tumors by adrenal CT. Of the 25,356 enrolled for adrenal imaging, 1.4% (351) were found to have adrenal tumors. The prevalence was higher in men than women (1.6% vs 1.2%) and increased with age, from 0.2% among those aged 18-25 years to 3.2% in those older than 65 years.
The median diameter among the detected adrenal tumors was 15 mm (range 10-45 mm). Only two tumors had diameters of 40 mm or greater. Of 337 participants with radiologically diagnosed “adrenocortical adenoma,” 212 completed functional assessment and 125 (37%) declined or did not complete the assessment.
Noncompleters were older and had higher systolic blood pressure than those who completed the assessment, and the lack of hormonal testing in the non-completer group particularly because they were older and more likely to have hypertension means both mild autonomous cortisol secretion and primary aldosteronism could have been more prevalent in this group, say the authors and editorialist.
Of those who did a complete functional assessment, 69.3% (147) had nonfunctioning adenomas and 30.7% (65) had adrenal tumors with steroid hormone secretion. Of the latter, 18.9% (40) had cortisol autonomy and 11.8% (25) had primary aldosteronism. No malignant tumors or pheochromocytomas were found.
Bancos notes: “Further studies are needed to improve our understanding of observed differences in the prevalence and type of hormonal excess.”
The proportionsof patients with nonfunctioning adenomas were similarly high across all age groups, at 72.2% in those less than aged 46 years, 67.8% in those aged 46-65 years, and 72.2% in those aged 66 years and older. Of the 25 participants diagnosed with primary aldosteronism, three were diagnosed with an aldosterone-producing adenoma, 17 with bilateral adrenal hyperplasia, and five with an indeterminate subtype.