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Epic Test Code LAB532 Renin Activity, Plasma

Additional Codes

MML Code: PRA

LIS Code: REMPR

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Renin Activity, P

Method Name

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

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

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma EDTA Frozen 14 days


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.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

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 Type

Plasma EDTA

Specimen Minimum Volume

0.5 mL

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)

Report Available

2 to 5 days

Day(s) Performed

Monday through Friday, Sunday

CPT Code Information

84244

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

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.

Special Instructions

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.

Cautions

Angiotensin-converting enzyme (ACE) inhibitors have the potential to falsely elevate plasma renin activity (PRA). Therefore, in a patient treated with an ACE inhibitor, the findings of a detectable PRA level or a low serum aldosterone/PRA ratio do not exclude the diagnosis of primary aldosteronism. In addition, a strong predictor for primary aldosteronism is a PRA level undetectably low in a patient taking an ACE inhibitor.

Specimen Retention Time

14 days

Forms

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

-General Request (T239)

-Cardiovascular Test Request (T724)