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Test Name:
Renin Activity, Plasma
- SBMF No:
30073 - Performance Lab Name:
Manual Lab - Test Mnemonic:
RENIN ACT- - ABN:
Not required - CPT Code:
84244 - LOINC Code:
2915-7 - Also Known As:
Plasma Renin Activity
PRA - Also See:
30066 Aldosterone, Serum or Plasma
30074 Aldosterone/Renin Activity Ratio - Spec Type:
Plasma - Spec Container:
Lavender top (EDTA) tube - Pref Vol:
1.0 mL - Min Vol:
0.5 mL - Fasting:
No - Spec Collect:
- Routine venipuncture
- – Supine sample before patient arises in morning
– Upright sample from patient who has been upright at least 2 hours
- Spec Process:
Within 6 hours of collection, centrifuge 15 minutes
Transfer plasma to separate plastic tube and freeze
Separate samples must be submitted when multiple tests are ordered - Spec Store Transport:
Frozen - Spec Stability:
6 hours room temperature (20-30°C) - prior to centrifugation
Refrigerated (2-8°C); Unacceptable
1 month frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Hemolyzed, lipemic, or icteric sample
Anticoagulants other than EDTA such as heparin or citrate
Refrigerated sample - Spec Remarks:
Do not expose sample to refrigerated temperatures since refrigerated temperatures can cause cryoactivation of prerenin that may falsely elevate renin levels - Methodology:
Radioimmunoassay (RIA) - Clinical Significance:
Renin is released from the juxtaglomerular cells of the kidney. The enzyme acts in general circulation to cleave its substrate, an alpha-2 globulin synthesized by the liver, to produce the deca-peptide angiotensin I.
Angiotensin I is cleaved rapidly by the activity of converting enzyme, primarily in the lungs, to the biologically active octapeptide angiotensin II. In turn, angiotensin II is degraded rapidly to inactive peptide fragments by enzymes present in plasma and tissues, know as angiotensinases.
Angiotensin II has an extremely short in vivo half-life, but it is the most potent vasopressor known. Angiotensin II plays a key role in several forms of hypertension, as well as in blood pressure regulation. In addition, angiotensin II has been established as the major influence on aldosterone secretion by the adrenal gland.
Technical difficulties associated with the measurement of angiotensin II levels in blood have retarded general acceptance of its assay in the clinical laboratory. Since angiotensin I levels are a direct representation of plasma renin activity, the determination of plasma renin activity has been adopted widely to evaluate the renin-angiotensin system in disease states. Measurement of plasma renin activity in hypertensives is an important aid in the differential diagnosis of primary and secondary aldosteronism. Estimation of renin activity is also valuable in determining the prognosis and most appropriate therapy for people with essential hypertension.
- Reference Range:
Plasma Renin Activity (PRA)
with Normal Sodium Diet:Supine:
Upright:0.15-2.33 ng/mL/hr
1.32-3.95 ng/mL/hrPlasma Renin Activity (PRA)
with Restricted Salt Intake:Na+ Excretion
mEq/24 hrMean +/- 1 S.D.
ng/mL/hr0 - 30
30 - 75
75 - 150
> 15016.34 +/- 7.52
5.90 +/- 1.82
2.12 +/- 0.68
0.85 +/- 0.46 - Additional Test Info:
It is critical that physiological variables, such as the patient's posture and either sodium intake or 24-hour urinary sodium excretion, be considered for accurate interpretation of assay results. Age, sex, and race are also important factors for consideration.
Changes in PRA can be affected by a spectrum of drugs including diuretics, adrenergicangiotensin II antagonists, oral contraceptives or estrogen therapy, and mineralocorticoid antagonists. Use of diatrizoate as in renography can also affect PRA values. Failure to take into account the pharmacological contribution of the patient’s drug intake may lead to the misinterpretation of PRA values.
- Day Run:
Tue, Fri - Time Run:
8:00 am - Time Reported:
5:00 pm - Test Type:
ENZYME
