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22178 Aldosterone, 24 Hour, Urine (ALDU)

Aldosterone, 24 Hour, Urine (ALDU)
Test Code: ALDOUSO
Synonyms/Keywords
​Ref Lab Code: 8556, Aldosterone w/Sodium, U
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's syndrome)
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume
Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Urine​ Plastic, 10-mL urine tube​ 10 mL​ 1 mL​
Collection Processing Instructions

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

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. 
 
Indicate total 24 hour urine volume on request form. The total volume collected must be measured, recorded, and included with the test request
 
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 (see Mayo website).
Specimen Stability Information
Specimen Type Temperature Time
Urine​ ​ ​ Refrigerated (preferred)​ 28 days​
Ambient ​ 14 days​
Frozen ​ 28 days​
Rejection Criteria
​All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Interference

​The plasma renin activity (PRA) cannot be interpreted if the patient is being treated with spironolactone (Aldactone). Spironolactone (Aldactone) should be discontinued for 4 to 6 weeks before testing.

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 sodium aldosterone (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.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories
Tuesday, Thursday 2 days​
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
Test 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.

Reference Range Information
0-30 days: 0.7-11.0 mcg/24 hr
31 days-11 months: 0.7-22.0 mcg/24 hr
>= 1 year: 2.0-20.0 mcg/24 hr
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.
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​82088
Synonyms/Keywords
​Ref Lab Code: 8556, Aldosterone w/Sodium, U
Aldosterone with Sodium, Urine
Ordering Applications
Ordering Application Description
Centricity​ ​Aldosterone-24Hr
​Cerner ​Aldosterone 24 Hour Urine (8556)
​COM ​Aldosterone - Urine
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume
Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Urine​ Plastic, 10-mL urine tube​ 10 mL​ 1 mL​
Collection Processing

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

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. 
 
Indicate total 24 hour urine volume on request form. The total volume collected must be measured, recorded, and included with the test request
 
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 (see Mayo website).
Specimen Stability Information
Specimen Type Temperature Time
Urine​ ​ ​ Refrigerated (preferred)​ 28 days​
Ambient ​ 14 days​
Frozen ​ 28 days​
Rejection Criteria
​All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Interference

​The plasma renin activity (PRA) cannot be interpreted if the patient is being treated with spironolactone (Aldactone). Spironolactone (Aldactone) should be discontinued for 4 to 6 weeks before testing.

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 sodium aldosterone (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.

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's syndrome)
Reference Range Information
0-30 days: 0.7-11.0 mcg/24 hr
31 days-11 months: 0.7-22.0 mcg/24 hr
>= 1 year: 2.0-20.0 mcg/24 hr
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.
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories
Tuesday, Thursday 2 days​
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​82088
For most current information refer to the Marshfield Laboratory online reference manual.