Unilateral Adrenal Vein Sampling in Primary Aldosteronism

In this retrospective review performed at two institutions over the course of 10 years, 63 patients who underwent bilateral adrenal vein sampling were followed. Serum cortisol and aldosterone were assayed from each of the 63 patients’ right and left adrenal veins as well as from blood collected from the inferior vena cava. Additionally, presence or absence of adrenal nodules was recorded based on preprocedural CT imaging of the adrenal glands. Relative Aldosterone Secretion Indices (RASI) were calculated for each patient. Previously, RASI values over 2.55 for the culprit side and under 0.96 for the non-culprit side had been shown to be sensitive and specific in the identification of unilateral primary aldosteronism {Rossi, 2023}. Those patients who were referred for surgery were further followed, and review of electronic medical records was used to determine resolution of primary aldosteronism. Outcome was defined as correction of hyperaldosteronism.

Results: Of the 63 patients who underwent bilateral adrenal vein sampling, 28 patients were found to have significant lateralization between venous aldosterone levels sampled from the right and left adrenal glands. 18 of the 28 lateralized patients underwent adrenalectomy, 17 of whom demonstrated normalization of serum aldosterone following surgery. Of the 18 patients who underwent adrenalectomy, 14 had adrenal nodules detected on preprocedural imaging: 4 patients had bilateral adrenal nodules and 10 had nodules on the hyperfunctioning adrenal gland. RASI values for the surgical group ranged from 1.6 to 11.9 on the culprit side. Using a 2.55 RASI threshold as indication for surgery yielded 100% specificity and approximately 80% sensitivity.

Conclusion:

In the setting of primary aldosteronism, RASI values obtained by sampling of a single adrenal vein, particularly in the setting of a unilateral adrenal nodule, can be used to identify the hyperfunctioning adrenal nodule and predict a favorable response to unilateral adrenalectomy with a high degree of accuracy. Further research is indicated to determine if a lower RASI threshold could potentially improve sensitivity.