Incidence of adrenal masses eventually discovered in patients screened for primary aldosteronism.

Context: Biochemical screening for endocrine hypertension may be complex; the known presence of an adrenal mass markedly increases the pre-test probability for adrenal hypertension and may inform diagnostic efforts.

Objective: Model the potential incidence of adrenal masses that may be detected by routine adrenal imaging in patients with suspected endocrine hypertension.

Design: Retrospective cohort study.

Setting: Provincial administrative and clinical databases for radiology and biochemistry, Alberta, Canada.

Participants: Patients with hypertension and any measurement of aldosterone-renin-ratio (ARR), 2012-2019.

Main measures: Radiology report of any CT or MR abdomen performed for any reason 0-12 years following ARR. Patients with any pre-ARR imaging data between 2002-2024 were excluded. Presence of adrenal mass, size and density were recorded and stratified by imaging indication.

Results: Of 6942 unique hypertension patients with ARR, 1462(21%) had imaging done at some point after ARR; 912(62.4%) for indications unrelated to hypertension/adrenal and at a median 771 days (69-1577) post ARR. The incidence rate estimate was 7.2% (5.6-9.2%) of scans showed adrenal mass, median 1.4 cm (1.1-2.3), a rate well above modern series of adrenal incidentaloma prevalence in unselected adults. The number-needed-to-screen in this population was 14 (11-18) to detect an adrenal mass without a priori indication for adrenal imaging.

Conclusions: Among patients screened for PA but without prior or subsequent directed adrenal imaging, 1 in 14 were later found to have an adrenal mass on imaging done for other indications. Given the impact upon pre-test probability for endocrine hypertension and further investigation steps, routine adrenal imaging might be considered whenever PA suspicion is high.