Lab Test

Aldosterone, Urine

Test Codes

EPIC: LAB5929, Beaker: XALDU, Mayo: ALDU


Specimen Collection Criteria

Collect (preferred specimen): 24-hour urine sample with Acetic Acid added at the start of collection.

  • Keep 24-hour urine specimen iced or refrigerated during collection.
  • Include start and end dates and times for the collection period on the specimen container.
  • The specimen must be transported to the Laboratory immediately after the end of the collection interval.
Urine Preservative Options
No Preservative
6N Hydrochloric Acid
Boric Acid (10g)
Sodium Carbonate
50% Acetic Acid

Physician Office/Draw Specimen Preparation

Maintain preserved specimens refrigerated (2-8°C or 36-46°F), or unpreserved specimens frozen (-20°C/-4°F or below), and transport to the Laboratory immediately.

Preparation for Courier Transport

Transport: Entire preserved 24-hour urine collection, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

  • Random urine specimens.
  • Specimens not collected and processed as indicated.

In-Lab Processing

Measure total volume of 24-hour urine specimen. Record total volume and collection start and end dates and times in the LIS system. Adjust the pH of the specimen to between 2.0 and 4.0. Aliquot 10 mL from the well-mixed 24-hour urine collection. (Minimum: 1 mL)


Specimen Stability for Testing:

Room temperature (20-26°C or 68-78.8°F): 28 days
Refrigerated (with preservative) (2-8°C or 36-46°F): 28 days
Frozen (-20°C/-4°F or below): 14 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions. 


Sent to Mayo Clinic Laboratories in Rochester, MN.


Tuesday, Thursday.
Results available in 2-8 days.

Reference Range

By report.

Test Methodology

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


Normal aldosterone levels are dependent upon sodium intake. High sodium intake will tend to decrease aldosterone levels while low sodium intake will elevate aldosterone levels.

Clinical Utility

  • Aldosterone assays are useful in the diagnosis and treatment of aldosteronism, evaluation of adrenal function in non-edematous, hypertensive patient with alkalosis and hypokalemia, and in patients with adrenal hyperplasia accompanied by decreased renin.
  • The principal reason for the measurement of serum aldosterone is for the diagnosis of primary hyperaldosteronism which is most commonly caused by an aldosterone-secreting adrenal adenoma (rarely a carcinoma). About 10-15% of patients have bilateral adrenal hyperplasia and will not respond to unilateral adrenalectomy. This can be determined by measurement of differential adrenal vein aldosterone levels. This rare condition must be distinguished from secondary hyperaldosteronism, which is common, and may be found in association with cirrhosis, renal artery stenosis, renal cysts, nephrotic syndrome, or congestive heart failure.
  • Primary hyperaldosteronism should be suspected in patients who are hypertensive and hypokalemic. Urine potassium of less than 30 mmol/day essentially excludes the diagnosis.
  • Normal serum or plasma levels of aldosterone are dependent upon the sodium intake and whether the patient is standing or recumbent. High sodium intake will tend to suppress serum aldosterone whereas low sodium intake will elevate serum aldosterone levels.

CPT Codes

LOINC:  1765-7


Last Updated


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