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

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.