Abstract
Given the largely unexplored application of liquid chromatography-tandem mass spectrometry (LC-MS/MS) steroid analysis in primary aldosteronism (PA), we aimed to investigate its diagnostic utility in PA classification and to characterize steroid secretion patterns across PA subtypes. We retrospectively enrolled 67 patients with PA and collected samples from both peripheral and adrenal veins. We performed a steroid analysis to compare the steroid panel differences between aldosterone-producing adenoma (APA), bilateral adrenal hyperplasia (BAH), and unilateral adrenal hyperplasia (UAH). Analyses included steroid concentrations and secretion ratios, with the latter calculated as individual steroid concentrations divided by total steroid content. The concentrations of 18-hydroxycortisol (18-OHF) were higher in the peripheral veins of patients with APA than in those with BAH and UAH (p < 0.01). A threshold of 4.83 ng/mL for peripheral 18-OHF specifically identified APA cases. In APA cases, adrenal vein secretion ratios of aldosterone, 18-hydroxycorticosterone (18-OHB), and 18-OHF were significantly higher in dominant versus non-dominant adrenal veins (p < 0.001). A secretion ratio of 18-OHF ≥ 14.6‰ and 18-OHB ≥ 4.03‰ from the adrenal vein achieved 100% specificity for identifying the dominant secretory side in cases of APA. Collectively, our findings demonstrate that LC-MS/MS steroid profiling effectively differentiates APA from other PA subtypes. The biochemical criteria for the secretion ratios of 18-OHF and 18-OHB from the adrenal vein provide objective criteria for lateralization diagnosis in APA. These findings could refine diagnostic strategies for PA subtyping.