The Value of LC-MS/MS in Apparent Bilateral Aldosterone Suppression in Adrenal Venous Sampling for Primary Aldosteronism

Abstract Context Adrenal venous sampling (AVS) is recommended for subtyping primary aldosteronism (PA), however, it is unreliable when apparent bilateral aldosterone suppression (ABAS) occurs, defined as aldosterone/cortisol ratio in the adrenal vein being bilaterally lower than that in the inferior vena cava. The value of Liquid chromatography-tandem mass spectrometry (LC-MS/MS) in PA subtyping when ABAS occurs is unclear. Objective To determine whether LC-MS/MS can reduce the occurrence of ABAS and misdiagnosis of PA subtyping. Design, Setting, Participants and Main Outcome Aldosterone and cortisol in AVS samples from 219 patients with PA were measured by LC-MS/MS and immunoassay. Then ABAS occurrence and misdiagnosis rate of PA subtyping were calculated. Results Among 219 patients with PA, 111 and 60 received non-ACTH and ACTH-stimulated AVS, respectively, and 48 received both. In unstimulated AVS, LC-MS/MS reduced the ABAS occurrence compared to immunoassay [10.7% (17/159) vs. 3.1% (5/159)]. Among 159 patients with unstimulated AVS, there were 77 patients who had final subtyping diagnosis based on postoperative outcomes. The misdiagnosis rate of immunoassay and LC-MS/MS was 10.4% (8/77) and 9.1% (7/77), respectively. However, the misdiagnosis were more common in patients with ABAS than in those without ABAS. For immunoassay, five out of six ABAS patients were misdiagnosed, while 3/71 non-ABAS patients were misdiagnosed. For LC MS/MS, only one ABAS patient had follow-up outcome and he was misdiagnosed, while 6/76 non-ABAS patients were misdiagnosed. Similar results were found in ACTH-stimulated AVS. Conclusion LC-MS/MS measurement of aldosterone and cortisol is a new resolution when ABAS occurs.