Background and objectives: There is a high prevalence for primary hyperaldosteronism (PHA) in hypertensive patients. This retrospective study was performed to determine the role of adrenal scanning and adrenal vein sampling (AVS) in distinguishing unilateral autonomous adenoma from idiopathic bilateral hyperplasia (IHA).
Methods: 93 patients, admitted to the radiology department for AVS between 1996 and 2004, were enrolled. 44 had a diagnosis of PHA, 22 or whom had an adenoma and 22 had IHA.
Results: 17 of the 22 patients with adenoma and 15 with IHA had an aldosterone-renin ratio > 50. Adrenal CT or MR scanning was performed in 73 patients. Sensitivity and specificity were 56 % and 60 %, respectively, for CT and 57% and 67% for MR. In 87 patients AVS provided values for aldosterone (A) and cortisol (C) from the adrenal veins and vena cava inferior (VCI). Successful sampling (C-adrenal vein/C-VCI > 1.1) was achieved from 55 % of the right and from 92 % of the left adrenal veins. When AVS was successful on both sides, localizing adenoma was possible using A/C (site of adenoma) vs. A/C (contralateral) at a cut-off point > 3 (sensitivity 85 %, specifity 88 %). In patients with adenoma, aldosterone release was suppressed on the contralateral site (A/C-adrenal vein/A/C-VCI ratio = 0.8).
Conclusion: AVS is a useful tool for localizing unilateral autonomous adenoma. However, selective sampling often fails on the right adrenal vein, which limits its significance. In this case the A/C-adrenal vein/A/C-VCI in combination with the posture test should be utilized. CT or MRI are of limited value.