Laboratory Services

Renin Activity, Plasma

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Updated Test Information:

Test Description
Renin Activity, Plasma
Synonym(s)

PRA (Plasma Renin Activity)

Test ID
PRA
General Information

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)

  • Not useful for determination of plasma renin concentration

  • See Renin-Aldosterone Studies

Specimen Type

EDTA Plasma

Specimen Requirements

Lavender Top (EDTA)

Specimen Collection / Processing Instructions

  • Patient Preparation: The plasma renin activity cannot be interpreted if the patient is being treated with spironolactone (Aldactone). Spironolactone should be discontinued for 4 to 6 weeks before testing.

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

  • Submission Container/Tube: Plastic vial

  • Specimen Volume: 2 mL

  • Collection Instructions:

    • Draw blood in a chilled syringe from a patient in a seated position; place specimenin a chilled, lavender-top (EDTA) tube; and mix

    • Alternatively, draw blood directly in a chilled, lavender top (EDTA) tube

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

    • Refrigerate specimen during centrifugation and immediately transfer plasmato plastic vial. (If a refrigerated centrifuge is unavailable, chill the centrifuge carriers. Centrifuge specimen for ≤5 minutes, then promptly transfer plasma.)

    • Immediately freeze plasma



Stability

Frozen: 14 days

Unacceptable Specimen Conditions

Gross hemolysis

Limitations

Angiotensin converting enzyme (ACE) inhibitors have the potential to "falsely elevate" PRA. Therefore, in a patient
treated with an ACE-inhibitor, the findings of a detectable PRA level or a low SA: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.

Methodology

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

Estimated TAT

2-5 days

Testing Schedule

Monday through Friday

Retention

14 days

CPT Code(s)

84244

Additional Information
Minimum Sample Volume

1.15 mL

Reference Range
Children: Age (years) Mean* (ng/mL/hour) Range (ng/mL/hour)
0-2 4.6 1.4 - 7.8
3-5 2.5 1.5 - 3.5
6-8 1.4 0.8 - 2.0
9-11 1.9 0.9 - 2.9
12-17 1.8 1.2 - 2.4
Adults: Age (years) Sodium-depleted Sodium-replete Sodium-depleted Sodium-replete
18 - 39 10.8 1.9 2.9 - 24.0 ≤0.6 - 4.3
≥ 40 5.9 1.0 2.9 - 10.8 ≤0.6 - 3.0

*Mean data not standardized as to time of day or diet. Infants were supine, children sitting, adults were upright (peripheral vein specimens).

 

Performing Lab

Mayo

LOINC Code(s)

2915-7