Renin Activity, Plasma
Also known as: Plasma Renin Activity (PRA), PRA
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
The patient's posture at the time of collection should be noted. It is recommended to take the patient off medications for at least three weeks prior to sample collection. Sodium levels can affect renin; hence, a 24-hour urine sodium determination prior to testing is advised. Patients should be ambulatory for at least 30 minutes prior to collection to ensure accurate results.
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.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 2915-7
- 2915-7
Result Turnaround Time
4-7 days
Related Documents
For more information, please review the documents below
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.
Storage Instructions
Freeze
Causes for Rejection
Non-frozen sample received; non-separated sample received; non-EDTA plasma specimen; gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unstable |
| Refrigerated | Unstable |
| Frozen | 14 days |