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Test ID ALDU Aldosterone, 24 Hour, Urine

Reporting Name

Aldosterone, U

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)

Specimen Type

Urine


Advisory Information


Advice on stimulation or suppression tests is available from Mayo Clinic's Division of Endocrinology and may be obtained by calling Mayo Medical Laboratories.



Necessary Information


24-Hour volume is required.



Specimen Required


Patient Preparation: Spironolactone (Aldactone) should be discontinued for 4 to 6 weeks before testing.

Supplies: Urine tubes, 10-mL (T068)

Submission Container/Tube: Plastic, urine tube (T068)

Specimen Volume: 10 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. Add 25 mL of 50% acetic acid as preservative at start of collection. Use 15 mL of 50% acetic acid for children <5 years old. This preservative is intended to achieve a pH of between approximately 2 and 4.

Additional Information: See Urine Preservatives for multiple collections and Renin-Aldosterone Studies for more detailed instructions in Special Instructions.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

Reference Values

0-30 days: 0.7-11.0 mcg/24 hours*

31 days-11 months: 0.7-22.0 mcg/24 hours*

≥1 year: 2.0-20.0 mcg/24 hours

 

*Loeuille GA, Racadot A, Vasseur P, Vandewalle B: Blood and urinary aldosterone levels in normal neonates, infants and children. Pediatrie 1981;36:335-344

Day(s) and Time(s) Performed

Tuesday, Thursday; 1 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82088

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALDU Aldosterone, U 1765-7

 

Result ID Test Result Name Result LOINC Value
8556 Aldosterone, U 1765-7
TM47 Collection Duration 13362-9
VL45 Urine Volume 3167-4

Clinical Information

Aldosterone stimulates sodium transport across cell membranes, particularly in the distal renal tubule where sodium is exchanged for hydrogen and potassium. Secondarily, aldosterone is important in the maintenance of blood pressure and blood volume.

 

Aldosterone is the major mineralocorticoid and is produced by the adrenal cortex. The renin-angiotensin system is the primary regulator of the synthesis and secretion of aldosterone. Likewise, increased concentrations of potassium in the plasma may directly stimulate adrenal production of the hormone. Under physiologic conditions, pituitary adrenocorticotropic hormone can stimulate aldosterone secretion.

 

Urinary aldosterone levels are inversely correlated with urinary sodium excretion. Normal subjects will show a suppression of urinary aldosterone with adequate sodium repletion.

 

Primary hyperaldosteronism, which may be caused by aldosterone-secreting adrenal adenoma/carcinomas or adrenal cortical hyperplasia, is characterized by hypertension accompanied by increased aldosterone levels, hypernatremia, and hypokalemia. Secondary hyperaldosteronism (eg, in response to renovascular disease, salt depletion, potassium loading, cardiac failure with ascites, pregnancy, Bartter’s syndrome) is characterized by increased aldosterone levels and increased plasma rennin activity.

Interpretation

Under normal circumstances, if the 24-hour urinary sodium excretion is greater than 200 mEq, the urinary aldosterone excretion should be less than 10 mcg/24 hours.

 

Urinary aldosterone excretion greater than 12 mcg/24 hours as part of an aldosterone suppression test is consistent with hyperaldosteronism.

 

24-Hour urinary sodium excretion should exceed 200 mEq to document adequate sodium repletion.

 

See Renin-Aldosterone Studies in Special Instructions.

 

Note: Advice on stimulation or suppression tests is available from Mayo Clinic's Division of Endocrinology and may be obtained by calling Mayo Medical Laboratories.

Clinical Reference

1. Young WF Jr: Primary aldosteronism: A common and curable form of hypertension. Cardiol Rev 1999;7:207-214

2. Young WF Jr: Pheochromocytoma and primary aldosteronism: diagnostic approaches. Endocrinol Metab Clin North Am 1997;26:801-827

Analytic Time

2 days

Method Name

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

Urine Preservative Collection Options

Ambient

Yes

Refrigerated

Yes

Frozen

Yes

6N HCl

No

50% Acetic Acid

Preferred

Na2CO3

No

Toluene

Yes

6N HNO3

No

Boric Acid

Yes

Thymol

No