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Test Code PRA Renin Activity, Plasma

Reporting Name

Renin Activity, P

Useful For

Investigation of primary aldosteronism (eg, adrenal adenoma/carcinoma and adrenal cortical hyperplasia) and secondary aldosteronism (renovascular disease, salt depletion, potassium loading, cardiac failure with ascites, pregnancy, Bartter syndrome)

 

This test is not useful for determination of plasma renin concentration.

Specimen Type

Plasma EDTA


Specimen Required


Patient Preparation: For 4 to 6 weeks before specimen collection, spironolactone (Aldactone) should be discontinued, as plasma renin activity cannot be interpreted if the patient is being treated with spironolactone.

Collection Container/Tube: Chilled, lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.8 mL

Collection Instructions:

1. Draw blood in a chilled syringe from a patient in a seated position; place specimen in a chilled, 3-mL lavender-top (EDTA) tube and mix well. Alternatively, draw blood directly in a chilled, EDTA tube.

2. Immediately place EDTA tube into an ice-water bath until thoroughly cooled.

3. Immediately centrifuge using a refrigerated centrifuge and aliquot plasma into a plastic vial.

Note: If a refrigerated centrifuge is unavailable, chill the centrifuge carriers before use. Centrifuge specimen for 5 minutes or less, then promptly aliquot plasma into a plastic vial.

4. Immediately freeze plasma.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma EDTA Frozen 14 days

Special Instructions

Reference Values

0-2 years: 4.6 ng/mL/h (mean)* Range: 1.4-7.8 ng/mL/h

3-5 years: 2.5 ng/mL/h (mean)* Range: 1.5-3.5 ng/mL/h

6-8 years: 1.4 ng/mL/h (mean)* Range: 0.8-2.0 ng/mL/h

9-11 years: 1.9 ng/mL/h (mean)* Range: 0.9-2.9 ng/mL/h

12-17 years: 1.8 ng/mL/h (mean)* Range: 1.2-2.4 ng/mL/h

Mean data not standardized as to time of day or diet. Infants were supine, children sitting.

*Stalker HP, Holland NH, Kotchen JM, Kotchen TA. Plasma renin activity in healthy children. J Pediatr. 1976;89(2):256-258

 

Na-depleted, upright (peripheral vein specimen)

18-39 years: 10.8 ng/mL/h (mean)

2.9-24.0 ng/mL/h (range)

≥40 years: 5.9 ng/mL/h (mean)

2.9-10.8 ng/mL/h (range)

 

Na-replete, upright (peripheral vein specimen)

18-39 years: 1.9 ng/mL/h (mean)

≤0.6-4.3 ng/mL/hour (range)

≥40 years: 1.0 ng/mL/h (mean)

≤0.6-3.0 ng/mL/h (range)

CPT Code Information

84244

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PRA Renin Activity, P 2915-7

 

Result ID Test Result Name Result LOINC Value
8060 Renin Activity, P 2915-7

Clinical Information

The renal juxtaglomerular apparatus generates renin, an enzyme that converts angiotensinogen to angiotensin I. The inactive angiotensin I is enzymatically converted to the active octapeptide angiotensin II, a potent vasopressor responsible for hypertension of renal origin. Angiotensin II also stimulates the zona glomerulosa of the adrenal cortex to release aldosterone.

 

Renin secretion by the kidney is stimulated by a fall in glomerular blood pressure, by decreased sodium concentration at the macula densa at the distal tubule, or by stimulation of sympathetic outflow to the kidney, such as in renal vascular diseases.

Interpretation

A high ratio of serum aldosterone (SA) in ng/dL to plasma renin activity (PRA) in ng/mL/h, is a positive screening test result, a finding that warrants further testing. A SA:PRA ratio greater than or equal to 20 and SA of greater than or equal to 15 ng/dL indicates probable primary aldosteronism.

 

Kidney disease, such as unilateral renal artery stenosis, results in elevated renin and aldosterone levels. Kidney venous catheterization may be helpful. A positive test is a renal venous renin ratio (affected:normal) above 1.5.

 

For more information see Renin-Aldosterone Studies.

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-General Request (T239)

-Cardiovascular Test Request (T724)