Liquid Chromatography-Tandem Mass Spectrometry Outperforms Radioimmunoassay in Guiding Surgical Decisions Based on Adrenal Venous Sampling in Primary Aldosteronism.

Background: Adrenal venous sampling (AVS) is essential for diagnosing unilateral aldosterone oversecretion in primary aldosteronism (PA). Traditionally, AVS relies on radioimmunoassay (RIA) to measure plasma aldosterone concentration (PAC), although RIA has limited specificity and considerable variability. This study evaluated the role of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in AVS and its impact on clinical outcomes.

Methods: Among 230 patients with PA (May 2020 to April 2023) who underwent AVS, successful sampling was achieved in 182 patients (79.1%) under unstimulated conditions and 206 patients (89.6%) under stimulated conditions. PAC levels from peripheral and adrenal veins measured by LC-MS/MS were compared with RIA results. Patient outcomes were categorized according to the Primary Aldosteronism Surgical Outcomes criteria.

Results: LC-MS/MS showed significant correlations with PAC levels measured by RIA in AVS (r=0.40 [unstimulated] and r=0.56 [stimulated]; both P<0.001). However, lateralization concordance between RIA and LC-MS/MS was moderate, at only 57.7% (unstimulated) and 64.6% (stimulated). LC-MS/MS identified more unilateral disease than RIA under both unstimulated (61.5% vs. 37.4%, P<0.001) and stimulated conditions (36.4% vs. 9.7%, P<0.001). Patients achieving complete clinical success after adrenalectomy were more accurately identified by LC-MS/MS than RIA under stimulated (55.6% vs. 22.2%, P=0.035), but not in unstimulated conditions.

Conclusion: LC-MS/MS outperformed RIA in identifying unilateral disease, resulting in higher rates of complete clinical success in adrenalectomy patients when surgical decisions were based on LC-MS/MS lateralization results.