Aldosterone/Plasma Renin Activity Ratio, LC/MS/MS
Also known as: Plasma Renin Activity, LC-MS/MS, ALDO/PRA Ratio, PRA, Primary Aldosteronism
Use
The aldosterone–renin ratio (ARR) is used to screen for primary aldosteronism (PA). It helps distinguish renin-independent hypertension. Clinical interpretation employs algorithms where suppressed renin activity ( 15 indicate likely PA, per 2025 Endocrine Society guidelines.
Special Instructions
Pretest patient preparation includes mid‑morning blood collection after patient has been upright (sitting, standing, or walking) for at least 2 hours, then seated for 5–15 minutes prior to draw. Potassium levels should be assessed; low potassium may lead to false‑positive low aldosterone. Cease mineralocorticoid receptor antagonists (MRAs) or ENaC inhibitors 4 weeks prior.
Limitations
Moderate to gross hemolysis, use of plasma separator tubes, or thawed specimen are unacceptable. Interpretation may be affected by timing, posture, medications, and potassium status; pre‑analytical variables can influence renin and aldosterone measurements.
Methodology
Mass Spectrometry
Biomarkers
Result Turnaround Time
5-7 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1.8 mL
Minimum Volume
0.8 mL
Container
EDTA (lavender‑top) tube
Collection Instructions
Collect a mid‑morning blood sample after patient upright for minimum 2 hours, then sit 5‑15 minutes before collection
Storage Instructions
Transport frozen
Causes for Rejection
Moderate to gross hemolysis; plasma collected in plasma separator tube; received thawed
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 24 hours |
| Frozen | 28 days |