Aldosterone, 24-Hour Urine — Mass Rate (2 Days Post-Dexamethasone)
Measures the amount of aldosterone excreted over 24 hours, with collection occurring 2 days after a prescribed dexamethasone dose.
["This test measures urinary aldosterone and may help assess adrenal hormone activity when interpreted with other hormone and blood-pressure results."]
Key facts at a glance
- LOINC
- 57636-3
- Short code
- A-cortolone 2D p Dex 24h Ur-mRate
- Synonyms
- A-cortolone 2D p Dex 24h Ur-mRate
- Category
- liver
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82670
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
Aldosterone is a hormone made by the adrenal glands that helps regulate blood pressure, fluid balance, and sodium levels. This test measures how much aldosterone is released into the urine over a 24-hour period.
Why might I need this test?
Your clinician may order this test when evaluating high blood pressure, low potassium, or possible excess aldosterone production. The 2-day post-dexamethasone designation indicates that urine collection is timed after dexamethasone has been given as directed.
How is the test performed?
You collect all urine for 24 hours in the container provided by the laboratory. The laboratory then measures the total aldosterone excreted during that period and reports it as a mass rate.
How do I prepare for the test?
Take dexamethasone exactly as prescribed and begin the 24-hour urine collection at the time directed by your clinician. Keep the container closed, refrigerate it if instructed, and return all collected urine to the laboratory on time.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated urinary aldosterone result may support excess aldosterone production, which can contribute to high blood pressure and low potassium. A lower result may occur with adrenal hormone deficiency, reduced circulating volume, or other changes in fluid and electrolyte balance. Dexamethasone and other medications can affect the result, so this test should be interpreted by your clinician alongside symptoms, blood pressure, potassium, and other hormone tests.
Short name
24-Hour Urine Aldosterone
Frequently asked questions
Why is dexamethasone mentioned in the test name?
Does the test require a timed overnight urine collection?
Can I stop dexamethasone before the collection?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy