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HelpTest Code ALDNA Aldosterone with Sodium, 24 Hour, Urine
Reporting Name
Aldosterone with Sodium, UrineUseful For
Investigating primary aldosteronism (eg, adrenal adenoma/carcinoma and adrenal cortical hyperplasia) and secondary aldosteronism (eg, renovascular disease, salt depletion, potassium loading, cardiac failure with ascites, pregnancy, Bartter syndrome) in conjunction with urine sodium levels
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| ALDU | Aldosterone, U | Yes | Yes |
| NAU | Sodium, 24 HR, U | Yes | Yes |
Method Name
ALDU: Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
NAU: Potentiometric, Indirect Ion-Selective Electrode (ISE)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineNecessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Patient Preparation: Spironolactone (Aldactone) should be discontinued for 4 to 6 weeks before testing. The plasma renin activity cannot be interpreted if the patient is being treated with spironolactone.
Supplies: Sarstedt Aliquot Tube 5mL (T914)
Container/Tube: 2 Plastic, 5-mL tubes
Specimen Volume: 10 mL
Collection Instructions:
1. Add 25 mL of 50% acetic acid as preservative at start of collection. Use 15 mL of 50% acetic acid for children under the age of 5 years. This preservative is intended to achieve a pH of between approximately 2 and 4.
2. Collect urine for a full 24 hours (required) and record the total volume.
3. Place 5 mL of well mixed, 24-hour urine in plastic, 5-mL tube and label as Aldosterone.
4. Place 5 mL of well mixed, 24-hour urine in plastic, 5-mL tube and label as Sodium.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Specimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days | ||
| Ambient | 7 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Special Instructions
Reference Values
ALDOSTERONE
0-30 days: 0.7-11.0 mcg/24 h*
1-11 months: 0.7-22.0 mcg/24 h*
≥1 year: 2.0-20.0 mcg/24 h
*Loeuille GA, Racadot A, Vasseur P, Vandewalle B. Blood and urinary aldosterone levels in normal neonates, infants and children. Pediatrie 1981;36(5):335-344
SODIUM
41-227 mmol/24 h
If the 24-hour urinary sodium excretion is greater than 200 mmol, the urinary aldosterone excretion should be less than10 mcg.
Day(s) Performed
Tuesday, Thursday
CPT Code Information
82088-Aldosterone
84300-Sodium
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ALDNA | Aldosterone with Sodium, Urine | 94871-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| NA_24 | Sodium, 24 HR, U | 2956-1 |
| 8556 | Aldosterone, U | 1765-7 |
| TM47 | Collection Duration (h) | 13362-9 |
| TM11 | Collection Duration | 13362-9 |
| VL9 | Urine Volume | 3167-4 |
| VL45 | Volume (mL) | 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 individuals 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 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 mmol, 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.
Twenty-four-hour urinary sodium excretion should exceed 200 mmol to document adequate sodium repletion.
For more information see Renin-Aldosterone Studies
Note: Advice on stimulation or suppression tests is available from Mayo Clinic's Division of Endocrinology; call 800-533-1710.
Cautions
Angiotensin converting enzyme (ACE) inhibitors have the potential to "falsely elevate" plasma renin activity (PRA). Therefore, in a patient treated with an ACE-inhibitor, the findings of a detectable PRA level or a low sodium aldosterone/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.
Method Description
Sodium:
The ion selective electron (ISE) module indirectly measures the electromotive force (EMF) difference between an ISE and a reference electrode. The EMF of the ISE is dependent on the ion concentration of the sample. The EMF of the reference electrode is constant. An electronic calculation circuit converts EMF of the sample to the ion concentration of the sample.(Package insert: ISE indirect Na, K, Cl for Gen 2. Roche Diagnostics; V14.0, 02/2018)
Aldosterone:
Samples are spiked with deuterated internal standard and are hydrolyzed overnight with acid. Samples are then neutralized and extracted by solid phase extraction. The extracts are dried, reconstituted, and analyzed by liquid chromatography tandem mass spectrometry.(Taylor RL, Singh RJ. Validation of liquid chromatography-tandem mass spectrometry method for analysis of urinary conjugated metanephrine and normetanephrine for screening of pheochromocytoma. Clin Chem. 2002;48[3]:533-539; Wurth R, Tirosh A, Kamilaris CDC, et al. Volumetric modeling of adrenal gland size in primary bilateral macronodular adrenocortical hyperplasia. J Endocr Soc. 202029;5[1]:bvaa162)