Renin Activity, Plasma

Also known as: Plasma Renin Activity (PRA), PRA

Clinical Use

Use

Measurement of renin activity is useful in the differential diagnosis of individuals with hypertension. Renin levels will be elevated in patients with hypertension due to renal artery stenosis (ie, renovascular hypertension). Measurement of renin activity can also be useful in the diagnosis of primary aldosteronism. Patients with secondary aldosteronism tend to have low renin levels. Renin can also be used to assess the adequacy of steroid substitution in patients with adrenal insufficiency. Renin activity will be normal in patients with adequate supplementation and will be elevated when steroid substitution is inadequate.

Special Instructions

Not provided.

Limitations

The test was developed and its performance determined by LabCorp but has not been cleared or approved by the FDA. Renin activity can be influenced by dietary salt, medications, and physiological states like posture. It shows diurnal variation, highest in the morning. Influence from aging and renal ailments due to reduced renin capacity must be considered. Certain drugs can increase or suppress PRA levels, impacting diagnostic accuracy.

Test Details

Methodology

Mass Spectrometry

Biomarkers

Angiotensin I

Analyte

Renin Activity

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

2915-7 - Renin Plas-cCnc

Result Codes

2915-7 - Renin Plas-cCnc

Result Turnaround Time

4-7 days

Specimen

Plasma

Volume

1 mL

Minimum Volume

0.8 mL

Container

Lavender-top (EDTA) tube

Collection Instructions

Draw blood into an EDTA tube. Maintain at room temperature, centrifuge, and transfer plasma into a LabCorp PP transpak frozen purple tube with screw cap. Freeze immediately and maintain frozen until tested.

Patient Preparation

Patient should be off medications for at least three weeks. Ambulate for at least 30 minutes before collection. Sodium intake affects test results: restrict sodium for increased renin activity.