Serum/Plasma Free Aldosterone Concentration (24-Hour Urine Collection)
This test measures how much aldosterone your body releases over 24 hours in your urine. Aldosterone helps regulate blood pressure and fluid balance.
["Helps diagnose conditions like primary aldosteroneism (hyperaldosteronism)."]
Key facts at a glance
- LOINC
- 27844-0
- Short code
- GH sp21 p chal SerPl-mCnc
- Synonyms
- GH sp21 p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have symptoms like high blood pressure, low potassium levels, or unexplained swelling. It’s also used to check for conditions where your body produces too much aldosterone, which can affect how your kidneys handle salt and water.
What to Expect Before the Test
You’ll need to collect all your urine for 24 hours, starting from one point in time (usually midnight or noon) and ending at the same time the next day. Keep a record of everything you urinate, including any accidents. Drink plenty of fluids to help your urine flow normally.
What to Expect During the Test
No special preparation is needed beyond the urine collection. You’ll likely provide a sample at a lab after completing the 24-hour period. The lab will analyze your urine for aldosterone levels.
What the Results Mean
Higher than expected levels may suggest overactive adrenal glands or other conditions affecting your body’s sodium and potassium balance. Lower levels might indicate adrenal insufficiency or other hormonal issues. Your doctor will interpret results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated aldosterone levels can lead to high blood pressure, kidney problems, or low potassium, which may cause muscle weakness or irregular heart rhythms. Low levels may signal adrenal gland disorders or other conditions affecting hormone production. This test helps diagnose conditions like Conn’s syndrome or Cushing’s syndrome when combined with other tests.
Short name
24-Hour Aldosterone Urine
Frequently asked questions
How is aldosterone measured in urine?
Will I need to change my diet before the test?
Can I take my usual medications during the urine 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