Endocrine Abstracts

JOINT3812

Background: The role of adrenal vein sampling (AVS) in younger patients with primary aldosteronism (PA) remains debated. Endocrine Society (ES) Guidelines suggest that AVS may be avoided in patients ≤35 years with marked PA (aldosterone >831 pmol/l, spontaneous hypokalaemia), and a solitary adrenal lesion consistent with an adenoma. While some centres adopt this approach, others, including ours, perform AVS routinely on all patients with PA. However, imaging alone may misclassify laterality in a significant proportion of younger patients.

Aim: To assess the accuracy of imaging alone in distinguishing unilateral from bilateral PA in patients ≤35 years and evaluate the added diagnostic value of AVS.

Method: We retrospectively analysed 364 patients who underwent AVS for PA between 2011 to 2024, including 39 patients aged ≤35 years. Of these, 38 underwent either CT or MRI prior to AVS. Two radiologists independently reviewed imaging blinded to AVS results, while two endocrinologists blinded to imaging findings analysed AVS. Concordance between imaging and AVS was assessed.

Results: The mean age was 32 years, with 60% female. Median hypertension duration was 1.5 years (IQR: 1–5 years). All patients had biochemically confirmed PA with spontaneous hypokalaemia and were on two to three antihypertensive medications. AVS was successful in all cases. Among 39 patients, four were excluded due to inconclusive AVS results and missing imaging data. In the remaining 35, imaging identified unilateral adenomas (6–25 mm) in 82.9% (29/35) patients, bilateral adenomas in 8.6% (3/35), and normal adrenal glands in 8.6% (3/35). Among 29 unilateral cases on imaging, 13.8% (4/29) had discordant AVS findings, indicating bilateral disease. Discordant cases had lateralisation index <2 (range: 1.3–2.0) and/or contralateral suppression index >1, suggesting bilateral PA. Only one discordant case met ES criteria for marked PA, while the other three had milder disease. All discordant cases were managed medically, while 86.2% (25/29) underwent unilateral adrenalectomy, with histological confirmed adenoma.

Conclusion: While imaging alone correctly lateralised PA in 86.2% of cases, 13.8% of patients with unilateral adenomas had discordant AVS findings, indicating bilateral disease. Only one discordant case met the ES criteria for marked PA, supporting AVS omission in these patients. However, AVS remains essential for those with milder PA to prevent misclassification and unnecessary adrenalectomy.