8 a.m. draw time (after the patient is active for 2 hours) is recommended
Collection no later than 10 a.m. is preferred
Minimum Sample Volume
1.2 mL
Stability
Refrigerated (preferred): 28 days
Frozen: 30 days
Ambient: 4 days
Limitations
The plasma renin activity (PRA) cannot be interpreted if the patient is being treated with spironolactone (Aldactone). Spironolactone should be discontinued for 4 to 6 weeks before testing.
Late p.m. levels can be up to 30% lower than early a.m. levels. Supine values are on average 50% lower than upright collections. Sodium deplete subjects have significantly elevated serum aldosterone (SA) levels, potentially exceeding the upper limit of the salt replete upright reference range by several fold. To account for these variables, at least in part, it is recommended that PRA is measured concomitantly. In situations of physiological variability, PRA should be altered in the same direction as aldosterone. See Renin-Aldosterone Studies in Special Instructions.
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-Friday
Retention
14 days
CPT Code(s)
82088
Reference Range
Age
Range (ng/dL)
Condition
0 - 30 days
17 - 154
31 days - 11 months
6.5 - 86
12 months - 10 years
≤ 40
Supine*
12 months - 10 years
≤ 124
Upright*
≥ 11 years
≤ 21
a.m. peripheral venous specimen
*Loeuille GA, Racadot A, Vasseur P, Vandewalle B: Blood and urinary aldosterone levels in normal neonates, infants and children. Pediatrie 1981;36:335-344
