A Combined LC-MS/MS Method for the Analysis of Aldosterone and Plasma Renin Activity in Plasma for Clinical Research using the Xevo TQ Absolute

Importance of the Topic

Primary aldosteronism (PA) is one of the most common causes of secondary hypertension, driven by excessive aldosterone secretion from adrenal hyperplasia or benign tumors. Overproduction of aldosterone leads to increased sodium reabsorption and water retention, elevating blood volume and blood pressure. Monitoring both aldosterone and plasma renin activity (PRA) is critical for assessing the renin–angiotensin–aldosterone system (RAAS) status and for evaluating novel therapeutic interventions in clinical research.

Objectives and Study Overview

This work aimed to develop and validate a single LC-MS/MS assay capable of simultaneously measuring plasma aldosterone and PRA. The goal was to streamline workflows in clinical research by combining two analyte measurements into one robust, high-throughput method.

Methodology and Instrumentation

Calibrators were prepared using certified aldosterone reference material and angiotensin I standards in 2% bovine serum albumin (BSA) in phosphate-buffered saline (PBS). In-house quality control (QC) samples were made in BSA/PBS and K2EDTA plasma. Plasma samples were incubated with a generation buffer (sodium acetate, EDTA, acetic acid, SBTI, PMSF) at 37 °C for three hours to generate quantifiable angiotensin I. After protein precipitation and dilution, samples underwent solid-phase extraction on a Waters Oasis™ MAX µElution 96-well plate. Chromatographic separation was achieved on a Waters ACQUITY™ UPLC™ I-Class system with a Waters XBridge™ C8 column (2.5 µm, 2.1 × 50 mm) using a water/methanol/ammonium fluoride gradient. Detection and quantification were carried out on a Waters Xevo™ TQ Absolute mass spectrometer.

Main Results and Discussion

The combined assay exhibited no significant carryover or matrix effects. It demonstrated linearity over 10–2500 pg/mL for aldosterone and 0.1–25 ng/mL/hr for PRA, with lower limits of quantification of 10 pg/mL and 0.1 ng/mL/hr at <20% precision. Total precision and repeatability coefficients of variation (CVs) for low, mid, and high QC levels were all below 10% across five analytical runs (n=25). Comparison with independent LC-MS/MS methods showed strong agreement for both analytes, supporting the accuracy and reliability of the combined assay.

Benefits and Practical Applications

• Combines aldosterone and PRA measurement into a single analysis, reducing sample volume and processing time.
• Improves laboratory throughput and cost efficiency.
• Maintains high sensitivity and specificity suitable for clinical research.
• Offers potential for expansion into multiplexed proteomic and metabolomic workflows.

Future Trends and Applications

Further developments may include extending the panel to additional RAAS components, automating sample preparation, and integrating the method into high-throughput platforms. Regulatory validation could enable adoption in routine clinical diagnostics, supporting personalized medicine approaches in hypertension management.

Conclusion

A single LC-MS/MS protocol using SPE and UPLC–MS/MS analysis has been successfully established for concurrent quantification of aldosterone and plasma renin activity. The method delivers excellent linearity, precision, and minimal matrix interference, making it a powerful tool for clinical research applications.

Reference

Foley D. A Combined LC-MS/MS Method for the Analysis of Aldosterone and Plasma Renin Activity in Plasma for Clinical Research using the Xevo TQ Absolute. Waters Corporation.