Aldosterone
Label Mnemonic: ALDS
Epic code: LAB552
Downtime form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mailout Laboratory
6240-8 RCP
356-8593
Specimen(s):
Serum
Specimen Instructions:
Collection Instructions: 8 a.m. collection time (after the patient is active for 2 hours) is recommended; preferably no later than 10 a.m.
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
Preferred Minimum: 1.2 mL serum from red top tube
Rejection Criteria:
EDTA plasma
Delivery Instructions:
Deliver to laboratory immediately after collection.
Turn Around Time:
2 days upon receipt at reference laboratory
Reference Range:
0-30 days: 17-154 ng/dL*
31 days-11 months: 6.5-86 ng/dL*
1-10 years:
  < or =40 ng/dL (supine)*
  < or =124 ng/dL (upright)*
  > or =11 years: < or =21 ng/dL (a.m. peripheral vein 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.
Interpretive Data:
A high ratio of serum aldosterone (SA) in ng/dL to plasma renin activity (PRA) in ng/mL per hour, is a positive screening test result, a finding that warrants further testing. An SA/PRA ratio greater than or equal to 20 is only interpretable with an SA greater than or equal to 15 ng/dL and indicates probable primary aldosteronism.

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

Cautions:
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.

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)
CPT Code:
82088
 
See Additional Information:
Specimens Requiring Immediate Delivery