A11374 RAAS Triple A-Testing

Abstract

Objectives: RAAS Triple-A testing is a novel mass spectrometry based approach providing a comprehensive biochemical evaluation of the circulating renin-angiotensin-system (RAS) on the basis of equilibrium angiotensin levels and circulating aldosterone levels. Methods: RAS-Equilibrium-Analysis combines the robustness and accuracy of LC-MS/MS based quantification with the versatility of serum sampling to generate a highly accurate readout containing multiple layers of information regarding the biochemical features of the circulating RAAS. Equilibrium Angiotensin I (Ang I), Angiotensin II (Ang II) and Aldosterone were simultaneously quantified in 500 μl of standard collected serum samples from healthy volunteers or hypertensive patients receiving different anti-hypertensive first-line therapies. Results: ACE inhibitor therapy resulted in a significant reduction of the Ang II-to-Ang I-Ratio in equilibrium analysis, which was accompanied by an up-regulation of renin. Surprisingly, PRA showed a high correlation with the sum of equilibrium Ang I and Ang II, which was independent of ACE inhibitor treatment. While the ARR was strongly suppressed in the presence of ACE inhibitor treatment, the Aldosterone-to-Angiotensin II-Ratio (AA2-Ratio) was not affected, suggesting superior applicability in screening for primary aldosteronism (PA). Conclusion: RAAS Triple-A testing is a mass spectrometry based multiplex assay combining Ang I, Ang II and Aldosterone to novel angiotensin based surrogate markers for renin and ACE activity drawing a comprehensive picture of a patient's “RAAS Status” while further delivering a novel ACE independent screening test for PA, the AA2-Ratio, which might pave the way for patient screening hypertensive patients without the need of withdrawing anti-hypertensive therapies.