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Test ID ALDNA Aldosterone with Sodium, 24 Hour, Urine

Reporting Name

Aldosterone with Sodium, Urine

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)

Profile Information

Test ID Reporting Name Available Separately Always Performed
ALDU Aldosterone, U Yes Yes
NAU Sodium, U Yes Yes

Specimen Type

Urine


Specimen Required


Container/Tube: 2 Plastic, 5-mL tubes (T465)

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.

3. Place 5 mL of well mixed, 24-hour urine in plastic, 5-mL tube (T465) and label as Aldosterone.

4. Place 5 mL of well mixed, 24-hour urine in plastic, 5-mL tube (T465) and label as Sodium.

Additional Information:

1. 24-Hour volume is required.

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


Specimen Minimum Volume

Aldosterone: 1 mL/Sodium: 1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 14 days
  Frozen  14 days
  Ambient  7 days

Reference Values

ALDOSTERONE

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

1-11 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

 

SODIUM

41-227 mmol/24 hours

If the 24-hour urinary sodium excretion is >200 mmol, the urinary aldosterone excretion should be <10 mcg.

Day(s) and Time(s) Performed

Aldosterone: Monday, Thursday; 3 p.m.

Sodium: Monday through Sunday; Continuously

CPT Code Information

82088-Aldosterone

84300-Sodium

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALDNA Aldosterone with Sodium, Urine In Process

 

Result ID Test Result Name Result LOINC Value
NA_24 Sodium, 24 Hr, U 2956-1
8556 Aldosterone, U 1765-7
TM47 Collection Duration 13362-9
TM11 Collection Duration 13362-9
VL9 Urine Volume 3167-4
VL45 Urine Volume 3167-4
NACN Sodium Concentration 21525-1

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 >200 mEq, the urinary aldosterone excretion should be <10 mcg/24 hours.

 

Urinary aldosterone excretion >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 1977;26:801-827

Analytic Time

2 days

Method Name

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

NAU: Potentiometric, Indirect Ion-Selective Electrode (ISE)

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